Tag Archives: new horizons

Should Pluto be promoted to a planet again?

Pluto as seen by New Horizons during a flyby at a distance of 450,000 kilometers. The irridiscent colors are the result of scientists combining four images taken by the spacecraft. Credit: NASA.

In 2006, Pluto was relegated from being the ninth planet in the solar system after the International Astronomical Union (IAU) demoted it to a “dwarf planet”. Officially, Pluto is now known as  “minor planet 134340 Pluto.” 

Many astronomy buffs were disappointed by the new assignment, seeing the criteria for Pluto’s demotion as rather nitpicky or even arbitrary.

But don’t scratch Pluto off as a planet just yet. There are still many authoritative voices in science who argue that the frozen world on the outer rim of the solar system should truly be classed as a planet in its own right.

Why was Pluto demoted in the first place?

The existence of Pluto was first proposed in the early 20th-century by Percival Lowell, whose calculations showed that wobbles in the orbits of Uranus and Neptune must be caused by the gravitational pull of an unknown ninth planet. Pluto was confirmed a decade later, on March 13, 1930, at the Lowell Observatory in Flagstaff, Arizona, by astronomer Clyde W. Tombaugh.

Since then Pluto’s status as the solar system’s ninth planet remained unchallenged until astronomers discovered 2003 UB313, also known as Eris, which is nearly as large as Pluto, but with a lot more mass.

The discovery of Eris triggered a fiery debate among astronomers. If Pluto is a planet, then so should Eris. Eventually, both were classed as dwarf planets after the IAU issued new criteria for what constitutes a planet. Essentially, IAU says that a planet must:

  • Orbit around the sun;
  • Have sufficient mass to assume hydrostatic equilibrium (gets squished into a sphere-like object due to gravity);
  • clears the neighborhood around its orbit.

In August 2006, the IAU ruled that Pluto would no longer be considered a planet because it doesn’t “clear the neighborhood around its orbit.” Pluto’s oblong orbit overlaps that of Neptune, so it was disqualified.

Instead, the IAU classed Pluto as a dwarf planet, which is a celestial body that meets the first two criteria. Besides Pluto and Eris, there are three other known dwarf planets in the solar system: Ceres in the asteroid belt between Mars and Jupiter; Haumea, which is located beyond Neptune’s orbit, and Makemake, the second-largest Kuiper Belt object.

Why should Pluto be considered a planet again?

Bearing this in mind, it’s clear that had the IAU not stuck to its new rules, we would have had at least 13 planets in the solar system now. But why should that be a problem?

Many have criticized IAU’s definition of a planet, claiming the criteria are arbitrary. Among these critics is NASA administrator Jim Bridenstine, who during a keynote at the 2019 International Astronautical Congress said:

“I am here to tell you, as the NASA administrator, I believe Pluto is a planet,” before adding that “Some people have argued that in order to be a planet you have to clear your orbit around the sun. If that’s the definition we’re going to use then you could undercut all the planets—they’re all dwarf planets—because there isn’t a planet that clears its entire orbit around the sun.”

The NASA chief is referring to asteroids, which regularly whizz past all the planets in the solar system.

“I think it’s a sloppy definition,” said Bridenstine. “I think the way you should define a planet is based on its intrinsic value, not values that constantly change like orbital dynamics.” 

Naming planets: a bureaucratic decision?

Bridenstine’s stance on Pluto is supported by the authors of a study published in a 2019 edition of the journal Icarus by a team of researchers led by Philip Metzger, a planetary physicist with the Planetary Science faculty at the University of Central Florida. Although the paper doesn’t focus on Pluto specifically, the authors explain how even asteroids were recognized as planets until the 1950s.

“In the 1950s, developments in planet formation theory found it no longer useful to maintain taxonomic identification between asteroids and planets, Ceres being the primary exception. At approximately the same time, there was a flood of publications on the geophysical nature of asteroids showing them to be geophysically different than the large planets. This is when the terminology in asteroid publications calling them planets abruptly plunged from a high level of usage where it had hovered during the period 1801–1957 to a low level that held constant thereafter,” the scientists wrote.

In effect, asteroids were reclassified as non-planets based on their geophysical characteristics. By extension, all cosmic bodies should also be classified by their geophysical characteristics and not arbitrarily through voting by a panel.

“I believe the IAU made several deep mistakes and so the definition is not valid and not scientifically useful and should be rejected. First, definitions should never be voted on for taxonomical concepts like “planet” because taxonomy is supposed to evolve and develop as an integral part of the science. By voting on a particular taxonomical choice they shut down that portion of the scientific process. So the entire vote was anti-science to begin with,” Metzger told ZME Science.

Metzger adds that the IAU actually violated their principles, “including their explicit statutes and bylaws, which require the actual language of a proposed vote to be reviewed by all the members for four months before the assembly.”

Since the IAU was in a hurry to force a decision, the organization violated its by-laws by not sharing the proposal text until the 2006 assembly.

“That was the first violation, the first mistake. Then the proposal was rejected at the convention, and since they had already set the precedent of breaking the rules they continued blindly breaking the rules even more. So they made up the definition during the assembly, giving nobody anywhere else in the world any time to digest it, giving nobody the choice to come to the meeting to present a well reasoned and well-researched case to sway the outcome, and they forced a vote. They got a deep split in the votes, proving there really is no consensus, but one side won so they declared that the deed was done. That became highly politicized and caused people to take sides and get emotionally involved, so now most people have an attitude about the whole thing and it has poisoned the ability to readdress the question,” Metzger said.

Perhaps you’ve noticed a pattern: the main objection that Pluto planetary advocates have against the IAU decision is that it didn’t follow a scientific process. Instead, it was based on a subjective, bureocratic process.

“Nobody is creating a theory about how objects that fail to clear their orbits are fundamentally different than those that do clear their orbits or those that are satellites of another planet. Nobody has ever proposed differences in geology, geochemistry, atmospheres, oceans, the emergence of life, mineralogy, etc., that are consistent one way in bodies that clear their orbits versus another way in bodies that do not clear their orbits. On the other hand, the term “planet” actually is being used to compare different planets across different dynamical states. So a paper might discuss Pluto, Triton, and Mars, calling them all “planets”, even though one cleared an orbit, one did not, and one was captured by Neptune to become a satellite,” Metzger said.

“Summary: the IAU definition does not match how scientists actually use the planet concept in doing real, reductionist science. The definition they created was actually designed to keep the number of planets small so school kids could memorize the planets, but having a small number is not the concern of science. The IAU abandoned science in order to create a cultural definition instead,” he added.

Wait, does that mean that the Moon and other satellites are planets too? Exactly.

“The idea that satellites are a distinct category with no overlap in the “planet” category is actually a recent invention. For almost all scientific history, moons were planets. What scientists used to say before the 1920s is that planets orbiting the sun are “primary planets” while planets that orbit another planet are “secondary planets” or just “satellite” or “moon” for short (but they were still known to be planets). Being a satellite was just a dynamic relationship that a planet could have with another planet.   When we decided that most asteroids are too small to be planets, in the 1960s, then we should have decided at the same time that the smaller satellites are also too small to be planets for the exact same reason, while the larger, round satellites are still planets. Unfortunately, astronomers had already become confused about satellites by the 1920s and forgot the meaning of the word “planet”, switching over to a cultural “folk taxonomy” that actually has its roots in astrology and geocentrism. The public was abandoning geocentrism in the late 1700s and early 1800s, and astrology was still very influential, and this led them to develop the idea that satellites are not planets. I am currently writing a manuscript that shows this. It was similar to the general public’s idea that green beans are a vegetable rather than a fruit, although biologists say a green bean is a fruit. The public develops a “folk taxonomy” that is human-centric and not scientifically reductionist, in contrast to the scientific taxonomy that is designed to align along the natural divisions of reductionist theory, thus providing deep explanatory power about nature,” Metzger said.

“So although the public is still unaware of this fact, it is true that planetary scientists are referring to moons as “planet”. Many of us do not even realize we are doing this. We say Titan has a planetary core, a planetary crust, a planetary radius, etc. They are “planetary” because they are characteristic of planets. Being a satellite has nothing to do with it. But if having these things are characteristic of planets, and bodies that are in both primary and secondary orbits have them equally, then every time we say “planetary” we are acknowledging that the type of orbit a body has is irrelevant to whether it is a planet or not.”

If Pluto is reinstated as a full-fledged planet, then the other four dwarf planets should join it too, bringing the total number of planets in the solar system to 13. However, by Metzger’s account of what constitutes a planet by scientific taxonomy, there ought to be at least 150 planets in the solar system.

“Most of them are in the Kuiper Belt. Ceres, which is in the asteroid belt, is also a planet. But also, large moons (satellites) are planets,” he said.

Another vocal supporter of Pluto’s planetary status is Alan Stern, principal investigator of NASA’s New Horizons mission, which flew by Pluto in 2015, revealing the icy body in unprecedented details, including a stunning heart-shaped nitrogen-ice plain.

Last year, Stern hosted an online debate for the Philosophical Society of Washington, in which he asked people to vote on whether or not Pluto should be reinstated as a planet. Before voting was opened, Stern explained their argument that a planet should be defined by its geophysical properties — if a body is massive enough to assume a nearly round shape but not massive enough to trigger nuclear fusion in its interior like a star, then that’s a planet. The poll closed with 130 votes in favor of making Pluto a planet again and 30 against it.

During his presentation, Stern went on to describe New Horizons’ findings, which show that Pluto has mountains, glaciers, avalanches, a liquid ocean beneath its icy crust, and a complex atmosphere. These are all hallmarks of planetary processes.

What’s more, the third criteria for planetary eligibility — that a planet has to clear its orbit of other bodies like asteroids — is not fair for bodies orbiting so far away from the sun. The more you move away from the sun, the harder it is to clear away small objects because the orbit is much slower than that of objects closer to the sun. This means that a planet needs to be increasingly massive in the outer reaches of the solar system in order to clear objects. In fact, Stern makes the assertion that not even Earth would qualify as a planet if it was on Pluto’s orbit. 

“The IAU definition is not aligned with useful reductionism. They voted to maintain the folk taxonomy of the public. Not only did they vote that moons are not planets, but they added an “orbit clearing” requirement to keep the number of planets small, so the set of planets would continue to be similar to the set that was known from geocentrism and astrology. Galileo rejected that set. He called the moons of Jupiter “planets”. He did not think dynamics should have anything to do with the definition of a planet. He did not think the number should be kept low to match the ancient geocentrism and astrology. It is really too bad that astronomers rejected Galileo and restored some of the ideas he fought to reject,” Metzger said.

“The basic problem is that modern astronomers have failed to realize that taxonomy, and evolving concepts like “planet”, are crucial to the program of science. They thought there was no harm in adopting a folk taxonomy from culture. They did not see any reason not to. This is where the most work needs to be done to repair the damage. The astronomers who believe the IAU’s planet definition is good need to get a much broader view of the functional role of taxonomy in science, to understand how important and beneficial taxonomy can be. If they think the IAU’s definition is good and beneficial, it is only because they have such a low concept of how much better things could be. Biologists understand this very well, so they demand that scientists retain “taxonomical freedom” and that taxonomy should never be a matter of regulation or restraint. Astronomers need some growth in this area,” he added.

More than 14 years after Pluto’s historic demotion to a dwarf planet, this debate is far from over. Perhaps Pluto might rejoin the ranks of the solar system’s roster of planets, but until then spirits remain high.

Bottom line: Pluto’s classification as a dwarf planet is arbitrary rather than the product of a scientific process.

Focusing on Arrokoth promises to reveal the Kuiper Belt’s secrets

Out beyond the orbit of Neptune and the solar system’s seven other major planets lies a ring of icy bodies known as the Kuiper Belt. The disc that is 20 times as wide and an estimated 200 times as dense as the asteroid belt houses a wide array of objects, including its most famous inhabitant — the dwarf planet Pluto. But, it holds more than objects of ice and rock. The Kuiper Belt may hold the secrets of how the planets of the solar system formed, and the raw materials that created the worlds around us and our own planet. 

“The Kuiper Belt is a repository of the solar system’s most primordial material and the long-sought nursery from which most short-period comets originate,” explains David C. Jewitt, an astronomer based at the University of California, Los Angeles, who is renowned for his study of the solar system and its smaller bodies. “The scientific impact of the Kuiper Belt has been huge, in many ways reshaping our ideas about the formation and evolution of the Solar System.”

Researchers now stand on the verge of unlocking these secrets with the investigation of the Kuiper Belt contact binary Arrokoth (previously known as ‘Ultima Thule’). On January 2019, the object — named for the Native American word for ‘sky’ — became the most distant object ever visited by a man-made spacecraft.

“Most of what we know about the belt was determined using ground-based telescopes. As a result, Kuiper Belt studies have been limited to objects larger than about 100 km because the smaller ones are too faint to easily detect,” says Jewitt. “Now, 5 years after its flyby of the 2000-km-diameter Kuiper Belt object Pluto, NASA’s New Horizons spacecraft has provided the first close-up look at a small, cold classical Kuiper Belt object.”

The data collected by the New Horizons probe has allowed three separate teams of researchers to conduct the most in-depth investigation of a Kuiper Belt object ever undertaken. In the process, they discovered that our current knowledge of how these objects form is very likely incorrect. From all the evidence the three teams collected, it seems as Kuiper Belts form as a result of a far more delicate, low-velocity process than previously believed. As most astrophysicists believe that these objects — planetesimals — acted as the seeds from which the planets grew, this new model changes our idea of how the solar system formed.

How Kuiper Belt Bodies Get in shape

The majority of the clues as to Arrokoth’s low-velocity formation originate from its unusual binary lobed shape. The larger lobe is joined to the smaller lobe by an extremely narrow ‘neck.’ What is especially interesting about this shape — reminiscent of a bowling pin or a snowman — is that the lobes are perfectly aligned. 

Scientists have used all available New Horizons images of Arrokoth, taken from many angles, to determine its 3D shape, as shown in this animation. The shape provides additional insight into Arrokoth’s origins. The flattened shapes of each of Arrokoth’s lobes, as well as the remarkably close alignment of their poles and equators, point to an orderly, gentle merger of two objects formed from the same collapsing cloud of particles. Arrokoth has the physical features of a body that came together slowly, with ‘locally-sourced’ materials from a small part of the solar nebula. An object like Arrokoth wouldn’t have formed, or look the way it does, in a more chaotic accretion environment. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Roman Tkachenko)

John Spencer, Institute Scientist in the Department of Space Studies, Southwest Research Institute in Boulder, Colorado, led a team of researchers that reconstructed Arrokoth’s 3-dimensional shape from a series of high resolution black and white images. Spencer’s paper concludes that Arrokoth’s lobes are much flatter than was previously believed but despite this, both lobes are denser than expected.

William McKinnon, Professor of Earth and Planetary Sciences at the Califonia Institute of Technology, and his team ran simulations of different formation methods to see which conditions led to the shape recreated and Spencer and his colleagues.

Velocity simulations of the formation of Arrokoth show that the unique shape of the bi-lobed comtact binary could only be acheived by a low-velocity gathering of small particles. (W.B McKinnon, et al)
Velocity simulations of the formation of Arrokoth show that the unique shape of the bi-lobed contact binary could only be achieved by a low-velocity gathering of small particles. (W.B McKinnon, et al)

McKinnon and his team discovered that the shape of Arrokoth could only be achieved as a result of a low-velocity formation–around 3 m/s. This presents a problem to current theories of how planetesimals form.

The suggested method of planetesimal formation suggests high-velocity particles smashing together in a process called hierarchical accretion. The simulations that McKinnon produced suggest that such high-velocity collisions would not have created a larger body, but rather, would have blown it apart. The geometrical alignment of the larger and smaller lobes indicates to the team that they were once co-orbiting bodies which gradually lost angular momentum and spiralled together, resulting in a merger.

“Arrokoth’s delicate structure is difficult to reconcile with alternative models in which Arrokoth Kuiper Belt objects are fragments of larger objects shattered by energetic collisions,” Jewitt says. This supports a method of planetesimal formation called ‘cloud collapse.’

Jewitt, Science, (2020)

“A variety of evidence from Arrokoth points to gravitational collapse as the formation mechanism.  The evidence from the shape is probably most compelling,” William Grundy of Lowell Observatory says. “Gravitational collapse is a rapid but gentle process, that only draws material from a small region. Not the much more time consuming and violent process of hierarchical accretion – merging dust grains to make bigger ones, and so on up through pebbles, cobbles, boulders, incrementally larger and larger,
with more and more violent collisions as the things crashing into each other.”

Grundy, whose team analysed the thermal emissions from Arrokoth’s ‘winter’ side, goes on to explain that the speed at which cloud collapse occurs and the fact that all the material that feeds it is local to it means that all the Kuiper planetesimals should be fairly uniform.

Cold Classicals: Untouched and unpolluted

Arrokoth is part of a Kuiper Belt population referred to as ‘cold classicals,’ this particular family of bodies is important to astrophysicists researching the origins of the solar systems. This is because, at their distance from the Sun within the Kuiper Belt, they have remained virtually untouched by both other objects and by the violent radiation of the Sun.

As many of these objects, Arrokoth in particular, date back 4 billion years to the very origin of the solar system, they hold an uncontaminated record of the materials from which the solar system emerged and of the processes at play in its birth.

Arrokoth's relative smoothness can be seen from comparisons to comets found in other areas of the solar system (J. R. Spencer et al., Science10.1126/science.aay3999 (2020).
Arrokoth’s relative smoothness can be seen from comparisons to comets found in other areas of the solar system (J. R. Spencer et al., Science10.1126/science.aay3999 (2020).

Arrokoth has a relatively smooth surface in comparison with other comets, moons and planets within the solar system. It does show the signs of a few impacts, with one very noticeable 7km wide impact crater located of the smaller lobe. This few craters dotted across Arrokoth’s surface do seem to point to a few small high-velocity impacts. The characteristics of Arrokoth’s cratering allowed the team in infer its age of around 4 billion years. This places its birth right around the time the planets had begun to form in the solar system.

“The smooth, relatively un-cratered surface shows that Arrokoth is relatively pristine, so evidence of its formation hasn’t been destroyed by subsequent collisions,” Spencer explains. “The number of craters nevertheless indicates that the surface is very old, likely dating back to the time of accretion.

“The almost perfect alignment of the two lobes, and the lack of obvious damage where they meet, indicate gentle coalescence of two objects that formed in orbit around each other, something most easily accomplished by local cloud collapse.”


As mentioned above, Will Grundy and his team were tasked with the analysis of thermal emissions in the radio band emitted by the side of Arrokoth facing away from the Sun.

W. M. Grundy et al., Science
10.1126/science.aay3705 (2020).

“We looked at the thermal emission at radio wavelengths from
Arrokoth’s winter night side.  Arrokoth is very cold, but it does still emit thermal radiation,” Grundy says. “The signal we saw was brighter, corresponding to a warmer temperature than expected for the winter surface temperature.  Our hypothesis is that we are seeing emission from below the surface, at depths where the warmth from last summer still lingers.”

Grundy’s team also looked at the colour imaging of Arrokoth with the aim of determining what it is composed of. “We looked at the variation of colour across the surface, finding it to be quite subtle,” he says. “There are variations in overall brightness, but the colour doesn’t change much from place to place, leading us to suspect that the brightness variations are more about regional differences in surface texture than compositional differences.”

The team determined that Arrokoth’s dark red colouration is likely to be a result of the presence of ‘messy’ molecular jumbles of organic materials that occur when radiation drives the construction of increasingly complex molecules–known as tholins.

“One open question is where Arrokoth’s tholins came from,” Grundy says. “Were they already present in the molecular cloud from which the Solar System formed?  Did they form in the protoplanetary nebula before Arrokoth accreted? Or did they form after Arrokoth accreted, through radiation from the Sun itself?”

The researcher says that all three are possible, but he considers the uniformity of Arrokoth’s colouration to favour the first two possibilities over the third. The team also searched Arrokoth for more recognisable organic molecules, spotting methanol–albeit frozen solid–but, not finding any trace of water. Something which came as a surprise to Grundy. “It was surprising not to see a clear signature of water ice since that’s such a common material in the outer solar system. Typically, comets have
around 1% methanol, relative to their water ice.”

The team believe that this disparity arises from the fact that Arrokoth accreted in a very distinct chemical environment at the extreme edge of the nebula which collapsed to create the solar system.

“If it was cold enough there for carbon monoxide (CO) and methane (CH4) to freeze as ice onto dust grains, that would enable chemical mechanisms that create methanol and potentially destroy water, too. But those mechanisms could only work where these gases are frozen solid,” Grundy says.  “Arrokoth appears to be sampling a region of the nebula where such conditions held. 

“We have not seen comets so rich in methanol, which probably means we have not seen comets that formed in this outermost part of the nebula.  Most of them probably originally formed closer to the Sun (or else at a different time in nebular history when the chemical conditions were somewhat different).”

Looking to future Kuiper Belt investigations

Investigating Kuiper Belt objects is no walk in the park, with difficulties arising from both the disc’s distance from the Sun and from the fact that Kuiper Belt objects tend to be very small. Grundy explains that as sunlight falls off by the square of its distance, object s as far away as the Kuiper Belt require the most powerful telescopes to do much of anything.

“Sending a spacecraft for a close-up look is great to do, but it took New Horizons 13 years to reach Arrokoth,” Grundy says. “It’ll probably be some time yet before another such object gets visited up-close by a spacecraft.”

Investigations of the Kuiper Belt aren't easy, the next flyby might be decades away ( Kuiper Belt Illustration – laurinemoreau.com)
Investigations of the Kuiper Belt aren’t easy, the next flyby might be decades away ( Kuiper Belt Illustration – laurinemoreau.com)

“For flybys, the journey times are very long–we flew for 13 years to get there–navigation is difficult because we don’t know the orbits of objects out there very well, we’d only been tracking Arrokoth for 4 years,” Spencer explains. “The round-trip light time is long, which makes controlling the spacecraft more challenging, and light levels are very low, so taking well-exposed, unblurred, images is difficult.”

Spencer adds that from Earth, objects like Arrokoth are mostly very faint, meaning only a small fraction of them have been discovered and learning about their detailed properties is difficult even with large telescopes. These difficulties mean that one of the things left to discover is just how common bi-lobed contact binaries like Arrokoth are in the Kuiper Belt. “Some evidence from lightcurves suggests up to 25% of cold classical could be contact binaries,” he says. ” We know that many of them are binaries composed of two objects orbiting each other, however.”

Fortunately, telescope technology promises to make leaps and bounds over the coming decades, with the launch of the space-based James Webb Space Telescope (JWST) in 2021 and the completion of the Atacama Desert based Extremely Large Telescope (ELT) in 2026.

“Both will help,” says Grundy.  “Larger telescopes are needed to collect more light and feed it to more sensitive instruments.  JWST and the new generation of extremely large telescopes set to come online over the coming years will enable new investigations of these objects.”

In terms of future spacecraft visits, Grundy believes that researchers and engineers should be thinking small, literally: “If technical advances were to enable highly miniaturized spacecraft to be flown to the Kuiper belt more quickly, that could enable a lot of things.  The big obstacles to doing that with today’sCubeSats are power, longevity, and communications, but the rapid advance of technology makes me hopeful that it will be possible to do a whole lot more with tiny little spacecraft within a few decades. 

“It’s funny how progress calls for ever bigger telescopes and ever smaller

 Future advances in telescope technology promised more detailed examinations of Kuiper Belt objects like Arrokoth. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/National Optical Astronomy Observatory)
Future advances in telescope technology promised more detailed examinations of Kuiper Belt objects like Arrokoth. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/National Optical Astronomy Observatory)

Of course one of the most lasting changes that result from this landmark triad of studies on Arrokoth published in Science is the move away from hierarchical formation models and the adoption of a gravitational or cloud collapse model to explain the creation of planetesimals. This shift will resolve one of the long-standing issues with the hierarchical model, the fact that they work quite well to grow things from dust size to pebble size, but once pebble size is reached, the particles quickly spiral-in toward the Sun. 

“I think it will shift the focus to the circumstances that trigger the collapse.  It’s a very fast way of making a planetesimal–decades instead of hundreds of millennia–but the circumstances have to be right for instabilities to concentrate solids enough for them to collapse,” Grundy explains. “It will be interesting to map out where and when planetesimals should form, what their size distributions should be, and where the solids that they are formed from should have originated.”

Original research:

W. M. Grundy et al., Science
10.1126/science.aay3705 (2020).

W. B. McKinnon et al.,
Science 10.1126/science.aay6620

J. R. Spencer et al., Science
10.1126/science.aay3999 (2020).

D. C. Jewitt et al., Science
10.1126/science.aba6889 (2020).

New Horizons beams back clear image of farthest object ever visited in the solar system



NASA’s New Horizons probe has radioed back a strikingly clear photo of a small, icy world called Ultima Thule. The object, which is one of the farthest we’ve ever identified, was encountered by the spacecraft a staggering 6.5 billion kilometers from Earth.

Previous observations of Ultima Thule weren’t very clear and had been open to interpretation. The new image, however, rather plainly shows that Ultima Thule looks like it’s made of two objects joined together, resembling a snowman. Every 15 hours, Ultima Thule completes a full rotation.

The encounter with Ultima Thule (which roughly translates as “beyond the borders of the known world”) has set the record for the most distant exploration of an object in the solar system. The previous record was also set by New Horizons during its flyby of the dwarf planet Pluto in 2015.

The larger spherical object is called “Ultima” while the smaller one is called “Thule”. The volume ratio between the two is approximately three to one.

Ultima Thule is found in a region of the solar system known as the Kuiper Belt — a group of small icy bodies which are remnants from the formation of the solar system. These objects, known as Kuiper Belt Objects (KBOs), are composed largely of ices – methane, ammonia, and water — similar in composition to comets.

The leftmost image shows Ulma Thule's true color as seen by one of New Horizon's instruments. The righthand image is a combination of the color and black&white (center) observations. Credit: NASA/JHU-APL/SWRI.

The leftmost image shows Ulma Thule’s true color as seen by one of New Horizon’s instruments. The righthand image is a combination of the color and black&white (center) observations. Credit: NASA/JHU-APL/SWRI.

According to New Horizons engineers, the brightest areas of Ultima Thule reflect just 13% of the incoming light that falls on them. To get a sense of how dark the object is, that’s a brightness similar to potting soil. Its color is mostly red, though, according to Carly Howett from the Southwest Research Institute (SwRI). This color is likely owed to the fact that the icy object was irradiated by high-energy cosmic rays and X-rays over billions of years.

NASA scientists think that the two spherical objects that make the Ultima Thule planetesimal — the basic building block of planets– likely coalesced around the time the solar system’s planetary bodies formed, about 4.6 billion years ago. As such, the icy object could offer clues as to how exactly Earth and other planets and moons in the solar system formed.

The best picture so far of the planetesimal, featured in the first half of this article, was taken while New Horizons was only 28,000 km above it. However, the probe has come even closer to Ultima Thule since that flyby, and NASA expects a picture with five times the resolution to reach their servers in February when the next downlink is scheduled.

To celebrate the milestone, Dr. Brian May — the lead guitarist of the band Queen, also an astrophysicist working directly with the New Horizons mission — wrote a song inspired by Ultima Thule. During a press conference, May told journalists that the song is about the human sense of adventure and discovery.

“Gradually it dawned on me that this mission is about human curiosity,” May said. “It’s about the need of mankind to go out there an explore and discover what makes the universe tick and this has been going on since the dawn of time.”

Pluto Flyby.

New Horizons wakes up for its most remote target yet — Ultima Thule

NASA’s New Horizons awakens from its slumber in time for the farthest planetary encounter in history — a flyby of Ultima Thule.

Pluto Flyby.

3D rendered artist’s impression of New Horizons flying by Pluto.
Image credits Kevin Gill.

The historic encounter is scheduled to take place on New Year’s Day in 2019. Since it wouldn’t do to sleep during such an important meeting, NASA woke the craft from its 165-day-long hibernation on June 4. This was the second period of inactivity for the craft, both of which were meant to conserve energy.  The craft will remain active through to late 2020 to beam back all the data from its contact with Ultima and the wider Kuiper Belt.

Not in Kansas anymore

The Kuiper Belt isn’t exactly a stone’s throw away — except maybe if that stone is a meteorite. It’s similar to the asteroid belt between Mars and Jupiter, only much more massive, and much farther away. The Kuiper Belt lies between 4.5 to 7.5 billion kilometers (2.8 to 4.6 billion miles) away from the Sun, roughly 20 to 50 times astronomical units (AUs), the distance between the Earth and our star.

New Horizons has already traveled an impressive stretch of this distance. It went past Pluto and is currently cruising through the belt properly, some 3.7 billion miles (6 billion kilometers) from Earth.

On June 4th, NASA ended the craft’s energy-saving hibernation mode, which was initiated last December. Ground control — situated at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland — received confirmation that onboard systems have resumed normal activity on June 5 2:12 a.m. local time, via NASA’s Deep Space Network. So far, everything seems in order and all systems are coming online without a hitch, the ream reports.

They will spend the next three days collecting navigation data from New Horizons and transmitting commands to prepare it for its Ultima flyby. It takes a lot of time to send a message that far into space, nearly 6 hours each way. The data traffic will include memory updates, subsystem and science-instrument diagnostics, as well as retrieval of information stored in New Horizon’s memory banks.

The whole process is estimated to take about two months, the team adds. On August 13th, the team will take the probe out of its stabilizing spin state. In mid- to late-August, they plan to instruct it to make distant observations of Ultima in order to refine its course towards the object. Its small size (about 20 to 23 miles in diameter) and the lack of light will make Ultima Thule hard to spot, but the team is anxious to try — this would be the first time any human has seen the object.

“Our team is already deep into planning and simulations of our upcoming flyby of Ultima Thule and excited that New Horizons is now back in an active state to ready the bird for flyby operations, which will begin in late August,” said mission Principal Investigator Alan Stern.

New Horizons is roughly 262 million kilometers (162 million miles) from Ultima — a bit under two AUs — and is speeding towards its mysterious target at a speed of 1,223,420 kilometers (760,200 miles) per day. Which is a lot.

NASA’s New Horizons probe snaps farthest image from Earth

As the interplanetary New Horizons probe woke up from its hibernating slumber, it turned its telescopic camera toward a field of stars and took a picture — making history.

For a brief period of time, this New Horizons Long Range Reconnaissance Imager (LORRI) frame of the “Wishing Well” star cluster, was the farthest image ever made by a spacecraft, breaking a 27-year record set by Voyager 1. About two hours later, New Horizons later broke the record again. Image credits: NASA/JHUAPL/SwRI.

Launched in 2006, the New Horizons mission stayed true to its name. It performed an unprecedented flyby study of the Pluto system in 2015, offering a dramatic view of the dwarf planet and its satellites. Now, the shuttle is currently on its way to study one or more other Kuiper belt objects.

Most of the time, New Horizons is sleeping — hibernating, to save energy. But every once in a while, it wakes up, and it snaps a few photos which it then beams back to Earth. With its latest wake-up, it broke the record for the farthest image humanity has ever taken away from Earth. Two hours later, it broke it again.

“New Horizons has long been a mission of firsts — first to explore Pluto, first to explore the Kuiper Belt, fastest spacecraft ever launched,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado. “And now, we’ve been able to make images farther from Earth than any spacecraft in history.”

New Horizons has observed several Kuiper Belt objects (KBOs) and dwarf planets at unique phase angles, as well as so-called Centaurs — former KBOs in unstable orbits that cross the orbits of the giant planets on the edge of our solar system. These December 2017 false-color images of KBOs 2012 HZ84 (left) and 2012 HE85 are, for now, the farthest objects from Earth ever captured by a spacecraft. They’re also the closest-ever images of Kuiper Belt objects. Image credits: NASA/JHUAPL/SwRI

When you’re traveling through 700,000 miles (1.1 million kilometers) of space each day, nothing stands still. New Horizons is one of only five shuttles which has managed to reach the escape velocity required to exit the solar system. It’s not just taking awesome photos on its path, but also carrying measurements of the plasma, dust and neutral-gas environment along the way, enabling astronomers to better understand the outskirts of our solar system. Now, it’s heading towards the Kuiper Belt, the circumstellar disk surrounding our solar system.

The Kuiper Belt is similar to the asteroid belt but is far larger: 20 times as wide and 20 to 200 times as massive. Specifically, New Horizons is targeting 2014 MU69, a mysterious object (or pair of two objects) which Alan Stern, mission principal investigator from the Southwest Research Institute (SwRI), has called “provocative” and a “scientific bonanza.”

New Horizons is reportedly healthy and everything is functioning as planned. The next awakening is scheduled for June 4. When that happens, it will break the record again.

You can follow New Horizons’ epic adventure here.

Did Pluto’s moon Charon harbor an ancient ocean?

As NASA’s New Horizons shuttle zoomed past Pluto, it snapped awesome photos not only of the “ex-planet”, but also of its moons. Now researchers are analyzing those pictures and reporting surprising finds – such as an ancient ocean on Charon, Pluto’s moon.

Too big for its skin?

Pluto’s Moon Charon A close-up of the canyons on Charon, Pluto’s big moon, taken by New Horizons during its close approach to the Pluto system last July. Multiple views taken by New Horizons as it passed by Charon allow stereo measurements of topography, shown in the color-coded version of the image. The scale bar indicates relative elevation.

The side of Pluto’s largest moon viewed by NASA’s passing New Horizons exhibits feature of “pull apart” tectonic faults. Faults are basically discontinuities in large volumes of rock, with significant displacements. The mass of rock can move towards each other, away from each other or slide by each other in a parallel line. Pull apart faults are areas where rocks move away from each other, and they are usually expressed by ridges, scarps and valleys – all of which can be observed on Charon. Some valleys are actually 4 miles (6.5 kilometers) deep, which is extremely impressive when you consider that its entire mean radius is 606 kilometers.

However, Charon can’t have tectonics like Earth has, because it doesn’t have a hot core and mantle that circulates under the crust, so researchers propose a different mechanism. Charon’s outside is primarily water ice. It’s all frozen, but this might have not always been always the case. When Charon was young, this layer was probably kept warmer by heat provided by the decay of radioactive elements, as well as Charon’s own internal heat of formation. It was probably hot enough to melt some of the water, so Charon had a subsurface ocean. But as Charon cooled over time, this ocean would have frozen. When water freezes, it expands, lifting the outer layers and pulling them apart.

This process makes a lot of geological sense, but the entire process must have been extremely violent. Charon exhibits one of the longest systems of chasms in the solar system,  running at least 1,100 miles (about 1,800 kilometers) long and reaching 4.5 miles (7.5 kilometers) deep. By comparison, the Grand Canyon is 277 miles (446 kilometers) long and just over a mile (1.6 kilometers) deep.


NASA finds vast quantities of frozen water on Pluto

New data provided by the New Horizons mission showed that water ice on Pluto is much more common than we thought.


Pluto turned out to be full of surprises. Not only does it have a thin atmosphere and is geologically active, but also hosts vast quantities of frozen water. The false color image above was derived from observations done with the Ralph/Linear Etalon Imaging Spectral Array (LEISA) instrument aboard New Horizons and shows where water is abundant.

According to this data, water seems to be considerably more widespread across Pluto’s surface than was previously known. Previous findings were deemed inaccurate because while they did detect ice, methane ice often masked water ice. The much more sensitive method used on the right involves modeling the contributions of Pluto’s various ices all together. This method has its own limitations in that it only highlights ices included in the model, but the model is constantly finessed.

“Water ice is Pluto’s crustal “bedrock,” the canvas on which its more volatile ices paint their seasonally changing patterns. Initial New Horizons maps of Pluto’s water ice bedrock compared LEISA spectra with a pure water ice template spectrum, resulting in the map at left,” NASA wrote.

Interestingly though, the data revealed little or no ice in the area called Sputnik Planum (the left or western region of Pluto’s “heart”) and Lowell Regio (far north on the encounter hemisphere). This could mean either that there is no water there, or that it is hidden beneath a thick blanket of methane ice (or something else). Sputnik Planum is a 1000-km-wide plain of frozen nitrogen and carbon monoxide ices, divided into polygonal cells which astronomers believe to act like convection cells.


NASA’s solar-powered Juno shuttle breaks record distance at 793 million km from the Sun

Juno is part of NASA’s New Frontiers program that wants to get up-close and personal with several planets in our solar system. The shuttle itself is going towards Jupiter to study its gravity field, magnetic field, and polar magnetosphere. Juno will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, how its mass is distributed, and its deep wind.

Juno is the first mission to Jupiter to use solar panels instead of the radioisotope thermoelectric generators (RTG) and recently, it became the farthest solar-powered trip in the history of space exploration.

Image credits: NASA / JPL.

Hitting a whopping 793 million kilometres (493 million miles) from the Sun, Juno’s accomplishment is even more impressive when you realize that the farther it goes away, the less energy it receives from the Sun.

“Jupiter is five times farther from the Sun than Earth, and the sunlight that reaches that far out packs 25 times less punch,” said Rick Nybakken, Juno’s project manager at NASA’s Jet Propulsion Laboratory. “While our massive solar arrays will be generating only 500 watts when we are at Jupiter, Juno is very efficiently designed, and it will be more than enough to get the job done.”

Its efficiency is owed in large part to the craft’s distinctive shape, jam packed with 18,698 individual solar cells. If it were located around the Earth, the volume of solar cells spread out over approximately 72 square metres (775 square foot) of panelling would generate approximately 14 kilowatts of electricity.

But Juno will get 832 million kilometres (517 million miles) away from the Sun, 6 times farther away then the Earth. This will really test its energy generating capacity to the maximum.

“Juno is all about pushing the edge of technology to help us learn about our origins,” said Bolton. “We use every known technique to see through Jupiter’s clouds and reveal the secrets Jupiter holds of our Solar System’s early history. It just seems right that the Sun is helping us learn about the origin of Jupiter and the other planets that orbit it.”

After arriving in Jupiter’s orbit, Juno will conduct 37 orbits, using its suite of instruments to study the gas giant. The estimated time of arrival is 4 July 2016.

Pluto’s Charon reveals colorful and violent past

NASA’s New Horizons shuttle wasn’t only taking mind blowing photos of Pluto, it was also peeking at Pluto’s moons, especially Charon – the largest one. The latest set of images analyzed by NASA researchers revealed quite a busy past, filled with violence and geologic activity.

Charon in Enhanced Color NASA’s New Horizons captured this high-resolution enhanced color view of Charon just before closest approach on July 14, 2015. The image combines blue, red and infrared images taken by the spacecraft’s Ralph/Multispectral Visual Imaging Camera (MVIC); the colors are processed to best highlight the variation of surface properties across Charon. Charon’s color palette is not as diverse as Pluto’s; most striking is the reddish north (top) polar region, informally named Mordor Macula. Charon is 754 miles (1,214 kilometers) across; this image resolves details as small as 1.8 miles (2.9 kilometers).

Charon is the largest and best studied moon of Pluto. It is a very large moon in comparison to its parent body, Pluto, and some astronomers have argued that Charon itself should be considered a dwarf planet like Pluto, and not a moon. nlike Pluto’s surface, which is composed of nitrogen and methane ices, Charon’s surface appears to be dominated by the less volatile water ice. The south polar area is dominated by a very large dark area informally dubbed “Mordor” by the New Horizons team. Aside from Mordor, however, New Horizons imaged very few other impact craters on Charon and found a youthful surface, adding support to the above theory that Charon is geologically active and thus probably differentiated (meaning it has a crust, a mantle and a core).

“We thought the probability of seeing such interesting features on this satellite of a world at the far edge of our solar system was low,” said Ross Beyer, an affiliate of the New Horizons Geology, Geophysics and Imaging (GGI) team from the SETI Institute and NASA Ames Research Center in Mountain View, California, “but I couldn’t be more delighted with what we see.”

For starters, the features are incredibly visible – you can see craters, ridges, and even fractures on its surface, but the most spectacular feature is definitely a huge canyon. The canyon stretches more than 1,000 miles (1,600 kilometers) across the entire face of Charon and likely around onto Charon’s far side, four times larger than the Grand Canyon, indicating a huge geologic upheaval in Charon’s past.

“It looks like the entire crust of Charon has been split open,” said John Spencer, deputy lead for GGI at the Southwest Research Institute in Boulder, Colorado. “With respect to its size relative to Charon, this feature is much like the vast Valles Marineris canyon system on Mars.”

High-resolution images of Charon were taken by the Long Range Reconnaissance Imager on NASA’s New Horizons spacecraft, shortly before closest approach on July 14, 2015, and overlaid with enhanced color from the Ralph/Multispectral Visual Imaging Camera (MVIC). Charon’s cratered uplands at the top are broken by series of canyons, and replaced on the bottom by the rolling plains of the informally named Vulcan Planum. The scene covers Charon’s width of 754 miles (1,214 kilometers) and resolves details as small as 0.5 miles (0.8 kilometers).

They also found that the moon’s southern part has way fewer craters than the northern part. The smoothness of the plains, as well as their grooves and faint ridges, are clear signs of wide-scale resurfacing. This could be the effect of a kind of cold volcanic activity, called cryovolcanism.

“The team is discussing the possibility that an internal water ocean could have frozen long ago, and the resulting volume change could have led to Charon cracking open, allowing water-based lavas to reach the surface at that time,” said Paul Schenk, a New Horizons team member from the Lunar and Planetary Institute in Houston.

Right now, the existence (and extent) of geological features on Charon has taken both astronomers and geologists by surprise, but they couldn’t be more thrilled. The good news is that even more pictures of Charon are currently being sent by New Horizons, and some of them will come in even better resolution. We’ll keep you posted as that happens.

This composite of enhanced color images of Pluto (lower right) and Charon (upper left), was taken by NASA’s New Horizons spacecraft as it passed through the Pluto system on July 14, 2015. This image highlights the striking differences between Pluto and Charon. The color and brightness of both Pluto and Charon have been processed identically to allow direct comparison of their surface properties, and to highlight the similarity between Charon’s polar red terrain and Pluto’s equatorial red terrain. Pluto and Charon are shown with approximately correct relative sizes, but their true separation is not to scale. The image combines blue, red and infrared images taken by the spacecraft’s Ralph/Multispectral Visual Imaging Camera (MVIC).

“I predict Charon’s story will become even more amazing!” said mission Project Scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Even more awesome images of Pluto released!

I know, I know, we’ve spoiled you with awesome photos of Pluto already, this couldn’t possibly surprise you, could it? Well, I dare say NASA has done it again – this new batch of New Horizons images is absolutely breathtaking.

Majestic Mountains and Frozen Plains: Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. The smooth expanse of the informally named Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high. Credits: NASA/JHUAPL/SwRI)

New Horizons is an interplanetary space probe launched to study Pluto and the outer areas of our solar system. On July 14, 2015 11:49 UTC (07:49 EDT), it flew 12,500 km (7,800 mi) above the surface of Pluto, making it the first human spacecraft to study the small planetoid. It took so many photos and analyzed so much information that NASA will be downloading it for about a year.

These oblique images offer an unprecedented look into Pluto’s landscapes, with dramatic backlighting from the Sun. The scene above measures 780 miles (1,250 kilometers) across. It almost looks like taken from a hot air balloon.

“This image really makes you feel you are there, at Pluto, surveying the landscape for yourself,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute, Boulder, Colorado. “But this image is also a scientific bonanza, revealing new details about Pluto’s atmosphere, mountains, glaciers and plains.”

Pluto’s Majestic Mountains, Frozen Plains and Foggy Hazes: Just 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. Credits: NASA/JHUAPL/SwRI

But it’s not just pretty pictures – New Horizons images offer a trove of valuable information about Pluto. Along with the previous photos, NASA now believe Pluto has an Earth-like hydrological cycle, but one which involves soft and exotic ices like nitrogen, instead of water.

“In addition to being visually stunning, these low-lying hazes hint at the weather changing from day to day on Pluto, just like it does here on Earth,” said Will Grundy, lead of the New Horizons Composition team from Lowell Observatory, Flagstaff, Arizona.

Pluto’s ‘Heart’: Sputnik Planum is the informal name of the smooth, light-bulb shaped region on the left of this composite of several New Horizons images of Pluto. The brilliantly white upland region to the right may be coated by nitrogen ice that has been transported through the atmosphere from the surface of Sputnik Planum, and deposited on these uplands. The box shows the location of the glacier detail images below.


Valley Glaciers on Pluto: Ice (probably frozen nitrogen) that appears to have accumulated on the uplands on the right side of this 390-mile (630-kilometer) wide image is draining from Pluto’s mountains onto the informally named Sputnik Planum through the 2- to 5-mile (3- to 8- kilometer) wide valleys indicated by the red arrows. The flow front of the ice moving into Sputnik Planum is outlined by the blue arrows. The origin of the ridges and pits on the right side of the image remains uncertain.


This comes as a surprise because NASA wasn’t expecting to find liquid or frozen nitrogen at all – let alone a hydrological cycle.

“We did not expect to find hints of a nitrogen-based glacial cycle on Pluto operating in the frigid conditions of the outer solar system,” said Alan Howard, a member of the mission’s Geology, Geophysics and Imaging team from the University of Virginia, Charlottesville. “Driven by dim sunlight, this would be directly comparable to the hydrological cycle that feeds ice caps on Earth, where water is evaporated from the oceans, falls as snow, and returns to the seas through glacial flow.Pluto is surprisingly Earth-like in this regard,” added Stern, “and no one predicted it.”

The next step is to study the photos and determine, from the morphology what kind of geological and erosional features are present on Pluto. They’ve already identified some interesting features.

ntricate Valley Glaciers on Pluto: This image covers the same region as the image above, but is re-projected from the oblique, backlit view shown in the new crescent image of Pluto. The backlighting highlights the intricate flow lines on the glaciers. The flow front of the ice moving into the informally named Sputnik Planum is outlined by the blue arrows. The origin of the ridges and pits on the right side of the image remains uncertain. This image is 390 miles (630 kilometers) across.


They’re here: NASA’s best up-close and personal photos of Pluto

New close-ups of Pluto’s surface have been revealed by NASA today, revealing a stunning variety of features on the frozen planetoid. A range of majestic mountains surrounds seemingly endless plains, and now, we get to see them all with unprecedented quality.

pluto new horizons

This synthetic perspective view of Pluto, based on the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft, shows what you would see if you were approximately 1,100 miles (1,800 kilometers) above Pluto’s equatorial area. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

It’s so spectacular that even NASA’s investigators were surprised.

“Pluto is showing us a diversity of landforms and complexity of processes that rival anything we’ve seen in the solar system,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute (SwRI), Boulder, Colorado. “If an artist had painted this Pluto before our flyby, I probably would have called it over the top — but that’s what is actually there.”

The New Horizons space probe was the first space probe to investigate Pluto up-close, but it already passed by the planetoid in July, so why are we seeing these photos just now? Well, New Horizons took a massive amount of data and it will take about a year before NASA is able to download all the data – and it will also take a while to analyze them. In the meantime, we have to settle for these gorgeous pics.

pluto new horizons

Mosaic of high-resolution images of Pluto, sent back from NASA’s New Horizons spacecraft from Sept. 5 to 7, 2015. The image is dominated by the informally-named icy plain Sputnik Planum, the smooth, bright region across the center. This image also features a tremendous variety of other landscapes surrounding Sputnik. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

But aside from being stunning, the photos highlight the surprising diversity of features on Pluto. Possible dunes, nitrogen ice flows that apparently oozed out of mountainous regions onto plains, and even networks of valleys that may have been carved by material flowing over Pluto’s surface were spotted.

“The surface of Pluto is every bit as complex as that of Mars,” said Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging (GGI) team at NASA’s Ames Research Center in Moffett Field, California. “The randomly jumbled mountains might be huge blocks of hard water ice floating within a vast, denser, softer deposit of frozen nitrogen within the region informally named Sputnik Planum.”

pluto new horizons

In the center of this 300-mile (470-kilometer) wide image of Pluto from NASA’s New Horizons spacecraft is a large region of jumbled, broken terrain on the northwestern edge of the vast, icy plain informally called Sputnik Planum, to the right. The smallest visible features are 0.5 miles (0.8 kilometers) in size. This image was taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Old, heavily cratered terrain sits next to young, pristine fields. But the most surprising things are the dunes (yet unconfirmed).

“Seeing dunes on Pluto — if that is what they are — would be completely wild, because Pluto’s atmosphere today is so thin,” said William B. McKinnon, a GGI deputy lead from Washington University, St. Louis. “Either Pluto had a thicker atmosphere in the past, or some process we haven’t figured out is at work. It’s a head-scratcher.”

The images are so detailed that you can actually do (large scale) geologic studies on them – which in itself is amazing. Who would have thought, a few decades ago, that we’ll be able to study the geology of something 3 billion kilometers away?

“This bonus twilight view is a wonderful gift that Pluto has handed to us,” said John Spencer, a GGI deputy lead from SwRI. “Now we can study geology in terrain that we never expected to see.”

pluto new horizons

This 220-mile (350-kilometer) wide view of Pluto from NASA’s New Horizons spacecraft illustrates the incredible diversity of surface reflectivities and geological landforms on the dwarf planet. The image includes dark, ancient heavily cratered terrain; bright, smooth geologically young terrain; assembled masses of mountains; and an enigmatic field of dark, aligned ridges that resemble dunes; its origin is under debate. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Discoveries aren’t limited to Pluto’s surface – New Horizons also snapped a few images of Pluto’s moons Charon, Nix, and Hydra, which will be released on Friday.

This image of Pluto’s largest moon Charon, taken by NASA’s New Horizons spacecraft 10 hours before its closest approach to Pluto on July 14, 2015 from a distance of 290,000 miles (470,000 kilometers. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Two different versions of an image of Pluto’s haze layers, taken by New Horizons as it looked back at Pluto’s dark side nearly 16 hours after close approach, from a distance of 480,000 miles (770,000 kilometers), at a phase angle of 166 degrees. Pluto’s north is at the top, and the sun illuminates Pluto from the upper right. These images are much higher quality than the digitally compressed images of Pluto’s haze downlinked and released shortly after the July 14 encounter, and allow many new details to be seen. The left version has had only minor processing, while the right version has been specially processed to reveal a large number of discrete haze layers in the atmosphere. In the left version, faint surface details on the narrow sunlit crescent are seen through the haze in the upper right of Pluto’s disk, and subtle parallel streaks in the haze may be crepuscular rays- shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the sun sets behind mountains on Earth. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute


new horizons speed

What flying at New Horizons’ speed would look like here on Earth

new horizons speed

A month ago the New Horizon spacecraft made a historic flyby over Pluto, marking the first time a man-made instrument has ventured this far in the planetary solar system. The journey took nine years, which might seem like a lot, but you need to remember we’re talking about nine billion miles. That’s quite fast, around 4 km/second actually. To get a sense of the kind of velocity involved, Clay Bavor – a Google product VC – made this GIF showing what flying at 11,278 metres would like from the cockpit of a Boeing 747, a SR-71 Blackbird and, finally, New Horizons. It quite speaks for itself.

For the simulation, Bavor used the top speeds for each vehicle: 885 km/h (747), 4,345 km/h (Blackbird) and 57,936 km/h (New Horizons). At this cruise speed, it would take you only 5 minutes to reach New York from San Francisco riding inside a New Horizons probe. Of course, there’s something called friction and at this speed the friction energy would be extremely intense. You’d only last a couple of seconds.

New Horizons isn’t done yet. While its main mission was to survey Pluto and its moons, the probe is now on route toward  the Kuiper Belt, a time capsule where freezing cosmic bodies go about their business as they have since the solar system was first formed 4.6 billion years ago. Specifically, New Horizons is destined for 2014 MU69, a comet-like body. The encounter is expected on January 1, 2019.

via Science Alert


Pluto is covered in ice and has an atmosphere, new pics reveal

New Horizons has sent over so much data that NASA will be analyzing and learning more about Pluto for over a year – such is the case now: these new images from New Horizons reveal flowing ice, impressive mountain ranges and a surprisingly thick atmosphere.

Artistic representation of Pluto’s ice. Image via Space Flight Insider.

In recent years, Pluto was quite a hot topic. First of all, there where the talks about not calling it a planet anymore, and then the demotion actually happened. Some people still call it a planet, but for all scientific purposes, it’s a dwarf planet; and now, recently, the New Horizons shuttle started to approach Pluto. First from a distance, shyly, then closer and closer, until it ultimately passed right in front of it, continuing its journey to the outskirts of the solar system.

Thanks to that, we’ve been learning more and more about this mysterious planetoid.

“Pluto has a very complicated story to tell,” Alan Stern, principal investigator for New Horizons, said at the news conference. “There is a lot of work that we need to do to understand this very complicated place.”

At a press conference, he showed a haze in a real-color picture of Pluto; that haze is Pluto’s atmosphere.

Pluto’s hazy atmosphere. Image via NASA.

“This is one of our first images of Pluto’s atmosphere. [It] stunned the encounter team,” said Michael Summers, a New Horizons co-investigator based at George Mason University in Fairfax, Virginia, at today’s news conference. “For 25 years, we’ve known that Pluto has an atmosphere. But it’s been known by numbers. This is our first picture. This is the first time we’ve really seen it. This was the image that almost brought tears to the eyes of the atmospheric scientists on our team.”

The haze extends at least 100 miles (160 km) above the surface of Pluto, five times more than models assumed; needless to say, this came as a surprise.

Pluto, in real color. Image via NASA.

In another set of images, Pluto revealed what appears to be a wide, flowing field of glaciers: the smooth, light-colored upper-left lobe of the heart-shaped region. However, unlike Earth’s glaciers, Pluto’s aren’t made from water, but from nitrogen, carbon dioxide and methane. This type of glaciers are much more malleable, even at extremely low temperatures. The images clearly show that Pluto’s ice is still flowing today. Scientists were thrilled.

“To see evidence of recent geological activity is simply a dream come true,” McKinnon said. “The appearance of this terrain, the utter lack of impact craters on Sputnik Planum, tells us that this is really a young unit.”

But there is one more element which adds to Pluto’s complexity: it’s almost perfectly spherical. We tend to think of Earth as a sphere, but Earth’s shape is far from being a perfect sphere. Why Pluto took this shape is still anyone’s guess, but astronomers already have a theory.

“We actually can’t detect any obliqueness or out-of-roundness in the body,” McKinnon said. Many other bodies in the solar system have distortions to their roundness, which “tells you about their history,” he said. “Pluto was probably spinning very, very fast after what we believe to be a giant impact that led to the formation of [Charon],” McKinnon added, noting that the gravitational pull of the two bodies on each other would have, over time, slowed down Pluto’s rapid rotation.

New Horizons made its Pluto flyby on July 14, and it will take 16 months before all the data is downloaded here on Earth. No doubt, more is to come.

Pluto through the years: GIF shows how our vision of the dwarf planet gradually improved

GIF via Explore.

OK, I know, you’ve already had your full of Pluto news, but seriously – this GIF is just spectacular. It shows just how far we’ve come, from not knowing about the planet, to seeing it just as a few white pixels, to incredibly clear images of Pluto’s surface, with even mountains being visible. Clyde Tombaugh first shot the planet at the Lowell Observatory in 1930, and the New Horizons took the most detailed pictures in its flyby just a few days ago.

If (plot twist) you somehow haven’t read all the new about Pluto and new Horizons, you may want to read these articles:

New Horizons images of Pluto hold big surprises for scientists

The soaring ice mountains of Pluto are accompanied by wide plains and mysterious deep troughs, show photographs received from NASA’s New Horizons spacecraft.

“When I saw this image for the first time, I decided I was going to call it not-easy-to-explain terrain,” said Jeffrey Moore, the leader of the geology, geophysics and imaging team for New Horizons, which visited Pluto this week. “You can clearly see that we’ve discovered a vast craterless plain that has some strange story to tell.”

Dr. Moore and other mission scientists described some additional data received during a press conference held on Friday. It has been a busy and exciting week for the team, as they try to make heads and tails of some of the more puzzling of images.

“I’m a little biased, but I think the solar system saved the best for last,” said S. Alan Stern, principal investigator for New Horizons.

It took the craft nine and a half years to journey the three billion miles to Pluto, and passed within 7,800 miles (roughly 12.553 km) of its surface on Tuesday. It was traveling to fast to be able to enter the dwarf planet’s orbit and zipped past, leaving it more than two million miles behind by now.

The spacecraft is expected to gather a huge amount of data: by the end of the month, its on-board memory is estimated to hold 50 billion bits of data. Due to the slow speed at which communications can be carried out over interplanetary distances, however, only 2 percent of it has been sent back to us.

The first close-up snapshot of Pluto, released on Wednsday, show its mountains to be 11,000 feet high bodies of water ice, not rock. What came as a surprise is that there were no craters on this part of the planet, of about 150 by 150 miles wide. Craters have been spotted in the global view of Pluto, and other regions could be geologically much older.

The new snapshot described by Dr. Moore on Friday was near the mountains and likewise devoid of craters, but it was almost flat. The lack of craters indicates that the surface was erased by erosion or tectonic activity in the recent geological past — within the past 100 million years.

Measurements of New Horizons’ “Ralph” tool found carbon monoxide ice, represented by the green graphic, on the western end of Pluto’s heart-shaped region.
Image via NASA

“This could be only a week old, for all we know,” Dr. Moore said.

Dr. Moore speculated that the troughs, zoning the plains into irregular shapes 12 to 20 miles across, could be caused by convection of carbon monoxide, methane and nitrogen ices below the surface, “creating the same sort of patterns that you see when you look at the surface of a boiling pot of oatmeal, or like the blobs in a lava lamp.”

Another possibility is that they could be similar to mud cracks on Earth, caused as the soil dries and contracts, Dr. Moore said. The shapes are reminiscent of those seen near the north pole on Mars, but it was too early to tell if similar geological processes had shaped them.

Pluto had its moment – now Charon, Pluto’s Moon is in the spotlight

OK, we all know New Horizons zoomed past Pluto, took some breathtaking pictures and then called back home to tell us everything’s fine. But let’s switch our attention a bit and focus on Charon – Pluto’s Moon that’s just as mysterious as its name implies.

Image via NASA.

Charon is the largest of the five known moons of the dwarf planet Pluto, at about 11% of the mass of Pluto. It was named after the ferryman in Greek mythology who would take people’s souls to Hades. Now, as NASA is receiving more and more data taken by the New Horizons, we’re getting the chance to look at more and more detailed pictures of Charon; one of them in particular has sparked researchers’ interest.

The latest sliver shows a 200-mile-long portion of Charon that shows some striking geological features: specifically, we see a deep depression with a high mountain rising out of it. It’s like a geological castle.

“The most intriguing feature is a large mountain sitting in a moat,” Jeff Moore, who leads New Horizons’ Geology, Geophysics and Imaging team, said in a statement. “This is a feature that has geologists stunned and stumped.”

Charon is also pummeled with impact craters, something which can’t be said about Pluto. Actually, let’s go back to Pluto for a second. The presence of mountains on the dwarf planet, along with the absence of impact craters seems to suggests active uplift phenomenon, which is extremely interesting, because there’s no apparent mechanism driving it. Oh, and whatever may drive it, Charon doesn’t have it, so the mystery deepens.

But this doesn’t mean that Charon isn’t active geologically. A previous image has already revealed a large smooth region in Charon’s southern hemisphere suggesting the contrary.

NASA plans to release even more high-resolution images of Charon’s surface in the coming days.

New Horizons and Pluto: Everything You Wanted to Know

Speeding at 14 km per second, NASA’s New Horizons shuttle went past Pluto, hurdling towards the edge of the Solar System. But regardless of what happens, New Horizons’ flyby of the dwarf planet will remained firmly anchored in the history of space exploration.

This is the best photo of Pluto we have. Yes, if you’re wondering, this is true color. Thank you, NASA!

“We have completed the initial reconnaissance of the Solar System, an endeavour started under President Kennedy more than 50 years ago and continuing to today under President Obama,” said the mission’s chief scientist, Alan Stern. “It’s really historic what the US has done, and the New Horizons team is really proud to have been able to run that anchor leg and make this accomplishment.”

As so many scientists have put it: this truly is space exploration. This is going past to the boundaries and past, reaching the very edges of our Solar System, just 112 years after the first plane took off the ground. Nasa’s science chief, John Grunsfeld, said:

“This is true exploration… that view is just the first of many rewards the team will get. Pluto is an extraordinarily complex and interesting world.”

So, we got a chance to get a good look at Pluto, and the tiny former planet is definitely an interesting and active place. It has an apparently active geology, a climate, and almost certainly, many secrets awaiting to be uncovered. Dr. Stern adds:

“On the surface we see a history of impacts, we see a history of surface activity in terms of some features we might be able to interpret as tectonic – indicating internal activity on the planet at some point in its past, and maybe even in its present. This is clearly a world where geology and atmosphere – climatology – play a role. Pluto has strong atmospheric cycles. It snows on the surface. These snows sublimate – (and) go back into the atmosphere – every 248-year orbit.”

The New Horizons team celebrates closest approach.

Just because Pluto isn’t a planet anymore, doesn’t make it a less interesting place. While we won’t go into the debate of whether or not Pluto is or should be considered a planet, it’s worth noting that there’s quite a significant generation gap here: people who learned the planets in recent years likely won’t consider it a planet, while many of us still do. In fact,  the head of NASA, Charles Bolden, still considers it to be a planet. He also praised the entire New Horizons project:

“We’re calling Pluto a planet, technically it’s a dwarf planet. I call it a planet, but I’m not the rule maker. We wanted to demonstrate that we could navigate the last known planet in our Solar System. That is an incredible technological achievement.” He was also surprised to see just how active and diverse Pluto is. Mr Bolden added: “ I expected to see some cold, grey icy planet. It has reddish tint, not unlike Mars. That’s fascinating. We continue to be mesmerised by this incredible planet and its moons.”

Measurements sent back by New Horizons as it came close to Pluto showed that the dwarf planet was 20-30 kilometers larger than previously thought, with a radius of 736 miles – which makes it larger than Eris, a body discovered in 2005. The fact that Pluto was smaller than Eris was one of the strongest arguments for reclassifying Pluto as a minor planet in 2006. He’s also not the only one excited to learn more about Pluto.

Pluto’s size relative to Earth (also presented: Charon, Pluto’s Moon)

“Maybe we need to reconsider its status again,” said Dr Daniel Brown, an astronomy expert at Nottingham Trent University. “What once was a planet and was demoted to a dwarf planet, obscure and without any clear images of the surface, will now be explored to great depth.”

British astronomer Brendan Owens, from the Greenwich Royal Observatory in London echoed the same thoughts:

“This is really unexplored territory. The images of Pluto we got previously have been only a few pixels across, just showing areas of light and dark on this world. Now we’re getting up close and personal, something that has never been done before. This whole region is hard for astronomers to explore because we rely on light, and at that distance so little sunlight falls on these objects that you have very little data to work with. Learning about the composition of Pluto may give us more of a handle on the make-up of the solar system.”

So what’s next for New Horizons? Well, after departing from Pluto, it will start exploring ‘The Third Zone’ also known as the mysterious Kuiper Belt – a region of the Solar System beyond the planets, that’s basically a bunch of uncharted debris left over from the solar system’s formation 4.56 billion years ago. The probe is still adequately fueled, so it can keep going until the Mid-2030s and keep sending valuable data back to Earth.

After that, it will leave the solar system.

“Over the next 20 years it could operate and return scientific data, from a Kuiper Belt flyby and then we have a chance to go further out of the heliosphere (Solar System) and potentially cross the interstellar boundary and sample interstellar space,” said Dr Stern.

As it turns out, NASA’s researchers made accurate predictions regarding Pluto.

If you still have questions, scientists working at the New Horizons mission were answering questions at Reddit. Here are some of the most interesting ones:

What is the most surprising thing you’ve discovered about Pluto since the mission began?

Charon’s dark pole surprised us quite a bit. We expected Charon’s surface to be mostly uniform and featureless.

What is next for New Horizons?
What do we hope to learn about Pluto?
What other information/pictures/data will New Horizons be sending back?
What has your day been like and what does it feel like to be part of the team?

1.Next is all of the data download. It will take ~16 months to download the amazing data.
2.We hope to learn about Pluto and its five known moons. The atmosphere, the geology, the composition of the rocks, and much much more.
3.New Horizons has seven instruments – ALICE, LORRI, PEPSSI, RALPH, REX, SDC, SWAP, so lots of data will be coming down in addition to the images you have seen already.
4.Today has been great. We all gathered and counted down to the closest approach. I can only imagine how exciting tonight will be when NH phones home.

The latest images suggest Pluto’s surface is much newer than Charon’s, even though the dwarf planet and it’s moon are the same age. Are there any theories in the works about the resurfacing process and it’s cause?

There are two likely reasons, but forthcoming New Horizons’ data will hopefully let us refine these or figure out a better reason. One is that Pluto is larger than Charon, so it can retain more heat and have active geology longer. Another is that Pluto has a tenuous atmosphere, and during the 248-year orbit around the sun, the atmosphere sublimates from one area in sun and is deposited in another in darkness, and then this reverses half-way through the orbit. This process is very slow, relatively speaking, but so is cratering.

Will we see detailed photos of Pluto’s moons in near future too?

Charon, yes. Hydra, yes (tomorrow or Thursday!). Nix, perhaps, but not Styx nor Kerberos.

Pluto has a heart – NASA reveals spectacular images of the dwarf planet

Pluto, the Solar System’s most well known planet wanna-be is having its week in the spotlight: NASA’s New Horizons probe is offering an unprecedented look at the dwarf planet, and already revealing some interesting features.

Note the brighter heart-like feature in the lower right. Seriously Pluto, why are you so cute? (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)

Astronomers were thrilled to present the clearest image of the brown-reddish Pluto taken by the Long Range Reconnaissance Imager (LORRI) onboard the New Horizons shuttle. As the shuttle passes right in besides Pluto, it will focus approximately on the same area, and we’ll be able to see it in even more detail.

“The next time we see this part of Pluto at closest approach, a portion of this region will be imaged at about 500 times better resolution than we see today. It will be incredible!,” said Jeff Moore, Geology, Geophysics and Imaging Team Leader of NASA’s Ames Research Center.

The image shows three distinct areas with different brightness, and it also shows that Pluto doesn’t only have a heart… it also has a whale! You can spot the “whale” (a dark spot) in the lower left of this new photo. The heart we’ve actually seen before, and NASA astronomers suspect it is the result of recently formed frost with a very distinguishing shape.

But it’s not just New Horizons that has its eyes peeled at Pluto. Much of NASA’s fleet of observatories have taken a break from their day to day work and are focusing on the dwarf planet.

“NASA is aiming some of our most powerful space observatories at Pluto,” said Paul Hertz, Astrophysics Division Director at NASA Headquarters, Washington. “With their unique capabilities combined, we will have a multi-faceted view of the Pluto system complementary to New Horizons data.”

Most notably, the Cassini probe will also gaze at Pluto – but although Cassini is the closest thing to Pluto except New Horizons, it’s still really far away. Pluto will be little more than a bright dot.

“The Cassini team has been pleased to provide occasional imaging support for New Horizons for several years to aid with the Pluto-bound spacecraft’s navigation. It’s great to provide one last look as it soars through the Pluto system,” said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California.

New Horizons is set to make its historical flyby of Pluto next week, we’ll keep you posted with updates.

New Horizons Shuttle Starts Preparing for Pluto Encounter

We’ve kept you up to date with New Horizon’s progress, and the pictures it took of Pluto; now, after 10 years and 3 billion miles, the shuttle will pass close to Pluto – only 7,800 miles away from it.

This image taken in late June shows Pluto (lower right) and Charon, its largest moon (upper left). New Horizons is set to pass closest to Pluto on July 14. JHUAPL/NASA/SWRI

With each passing day, we got a better look at Pluto, and with each passing day, we learned a lot about it, but it’s all going to get much better. On Tuesday the probe will begin an intensive nine-day study of Pluto and its moons.

The dwarf planet was discovered in 1930 and was originally considered the ninth planet from the Sun. Its status as a planet fell into question following further study of it and the outer Solar System over the following 75 years. After all these years, on 14 July 2015, the New Horizons probe will fly by Pluto, become the first spacecraft to ever do so. The goal of the mission is to understand the formation of the Pluto system, the Kuiper Belt, and the transformation of the early Solar System – yes, we can learn clues about all of those by studying Pluto.

The spacecraft will study the atmospheres, surfaces, interiors and environments of Pluto and its moons. It will also study other objects in the Kuiper Belt and keep an eye out for other interesting developments. The belt “contains a very large number — probably billions — of comets, and potentially other small worlds, perhaps even ones as large as Pluto.

But this is no easy feat. Pluto is so far away that it takes information four and a half hours to get from the spacecraft to Earth.

“From Earth to Pluto, where our spacecraft is, is going to be about 4 ½ hours,” says Alice Bowman, the Mission Operations Manager of New Horizons. “So the information that we’re receiving right now was sent 4 ½ hours earlier.”

This doesn’t only cause a lag in information sending, it also means that scientists can’t control New Horizons in real time – they designed in such a way that it adapted to problems and managed mostly by itself.

“No operator can sit on Earth and use a joystick to control where the spacecraft is looking or taking observations,” Bowman says. “Pretty much you have to make a very smart spacecraft.”

The stakes are high. We talk about Pluto a lot, but if we wrote all the specific data we know about it, we probably couldn’t even fill a piece of paper. This is basically the first serious look at an unexplored part of our solar system, and during the 9 days, New Horizons will make over a thousand scientific observations. Its scientific instruments will probe Pluto for evidence of its composition, terrain and atmosphere.

NASA spacecraft takes new photos of Pluto

In the past couple of months, we’ve posted quite a lot of articles about the New Horizons spacecraft zooming in on Pluto. It got close enough to see its moons, to see it in color, and to see it at unprecedented resolution. Now, New Horizons got even closer to Pluto and guess what – it took some even better photos.

“These new images show us that Pluto’s differing faces are each distinct; likely hinting at what may be very complex surface geology or variations in surface composition from place to place,” said New Horizons principal investigator Alan Stern of the Southwest Research Institute in Colorado.

The images were taken from just under 77 million kilometres away, using the Long-Range Reconnaissance Imager (LORRI) on New Horizons – a powerful telescopic camera. The shots were taken from 80, 77, and 75 million km away and they’re already significantly better than existing photos taken by Hubble.

“As New Horizons closes in on Pluto, it’s transforming from a point of light to a planetary object of intense interest,” said NASA’s Director of Planetary Science Jim Green. “We’re in for an exciting ride for the next seven weeks.”

In terms of scientific significance, the images seem to support the theory that Pluto might have polar ice caps – in a couple of months, when New Horizons gets really up close and personal with the planetoid, we’ll likely be able to answer that question.

“These images also continue to support the hypothesis that Pluto has a polar cap whose extent varies with longitude; we’ll be able to make a definitive determination of the polar bright region’s iciness when we get compositional spectroscopy of that region in July.”