Tag Archives: hubble

Hubble spots three galaxies dancing in epic photo

The two galaxies in the upper-right part of the image seem to be interacting with each other — potentially even merging.

NGC 7764A lies some 425 million light-years from Earth, in the constellation Phoenix, first described 400 years ago, on a celestial atlas called Uranometria. Although it’s so far away, Hubble was able to snap this image using both its Advanced Camera for Surveys (installed in 2002) and Wide Field Camera 3 (the most technologically advanced visible-light camera on Hubble, installed in 2009). Both are advanced systems designed to capture images deep in space.

The two right-side galaxies appear to be dancing around each other — a dance that is also potentially affected by the bowling-ball shaped galaxy on the right side of the picture. It’s not uncommon for galaxies to interact and even collide, although this process happens very slowly, and is not technically a collision (since galaxies have more empty space than stars and planets), but rather gravitational interactions between the components that make up the two galaxies. Colliding may cause the two galaxies to merge, if they don’t have enough momentum to continue traveling after the collision. When this happens, the two galaxies eventually fall back on each other and merge into one galaxy. When galaxies just pass through each other without merging, they mostly retain their material and overall shape.

It’s not clear which of these processes is going on here, or if there’s another process altogether — although a head-on collision appears unlikely. As NASA explains, the galaxy in the lower left may also be involved, given that it is relatively close. The European Space Agency (ESA) also seems pretty stoked about the shape the two galaxies are making as they interact.

“By happy coincidence, the collective interaction between these galaxies has caused the two on the upper right to form a shape, which from our solar system’s perspective, resembles the starship known as the USS Enterprise from Star Trek,” an ESA text notes.

The space agency also points out just how clunky the naming of these galaxies is. The three galaxies are called NGC 7764A1, NGC 7764A2, and NGC 7764A3, respectively. Astronomers need these complex but specific names to make sure they know exactly what object they’re talking about and prevent any confusion.

“This rather haphazard naming makes more sense when we consider that many astronomical catalogs were compiled well over 100 years ago, long before modern technology made standardizing scientific terminology much easier,” the article adds.

“As it is, many astronomical objects have several different names, or might have names that are so similar to other objects’ names that they cause confusion.”

Crumbled comet helps researchers understand how their tails form

Last year, researchers spotted what was going to be the brightest comet seen since 1997: C/2019 Y4 ATLAS. It is now helping us understand how comets form their tails.

The comet’s break up in April 2020, captured by Hubble. Image credits NASA / ESA / STScI / D. Jewitt (UCLA).

Much to their dismay, however, this body broke down into fragments sometime in April 2020, robbing everybody of a shining view. Not all is lost, however, as NASA and the European Space Agency’s Solar Orbiter managed to do a flyby of the fragments, giving us a very rare look at what happens after a comet breaks up.

The tail end

ATLAS was supposed to become easily visible even with the naked eye as it passed Earth in May of last year. But one month before that could happen, our satellites showed, ATLAS got progressively brighter. Finally, it crumbled before reaching Earth. The Hubble Space Telescope captured this event, despite it happening over 90 million miles away from our planet. Each fragment is around the size of an average house.

Still, the comet’s tail persisted after the breakdown, so the Solar Orbiter was tasked to observe the remains. All of the craft’s instruments were used to probe ATLAS’s remains for information, including an energetic particle detector, magnetometer, a radio wave detector, and solar wind analyzer.

Data from the magnetometer was particularly interesting, as it allowed ground control to see how the magnetic field of the comet’s tail interacted with the magnetic field carried through the solar system by the solar wind. This interaction is known to produce ion tails around comets, a fainter and smaller counterpart to their visible dust tails.

Based on the data recorded here, the team was able to model the magnetic field generated by the initial comet, revealing a surprising fact: it is weakest around the central dust tail. This is most likely produced by the comet’s ‘wake’ as it barrels through incoming solar winds. The comet’s ion tail is produced by this magnetic field warping in combination with chemical ions produced by the melting of the comet’s core.

“This is quite a unique event, and an exciting opportunity for us to study the makeup and structure of comet tails in unprecedented detail,” said Lorenzo Matteini, a solar physicist at Imperial College London and leader of the recent work, in a Royal Astronomical Society press release. “Hopefully with the Parker Solar Probe and Solar Orbiter now orbiting the Sun closer than ever before, these events may become much more common in future!”

The event, although it might seem inconsequential in the grand scheme of things, lets us understand comets and outer space just a little bit better. While we don’t have a practical use for such data right now, they might come in handy when and if humanity takes to the stars in meaningful numbers.

The findings have been presented at the National Astronomy Meeting 2021.

Illustration showing snapshots from a simulation by astrophysicist Volker Springel of the Max Planck Institute in Germany. It represents the growth of cosmic structure (galaxies and voids) when the universe was 0.9 billion, 3.2 billion and 13.7 billion years old (now). Image via Volker Springel/ MPE/Kavli Foundation.

What Is Dark Energy?

During the 20th century, the idea that the Universe existed in a steady state was seriously challenged and eventually dismissed by the discovery that the Universe is not only expanding but is also doing so at an accelerating rate. The reason for this accelerating expansion is thus far unknown, but scientists have given this force a name–albeit one that is a placeholder–dark energy.

Explaining this accelerating rate of expansion has become one of the most challenging problems in cosmology. The fact that the value for this acceleration varies wildly between theory and practical observations has created a raft of problems in itself. This means that the net result arising from any attempt to explain dark energy creates more questions than it answers.

Dark Energy: The Basics

Illustration showing snapshots from a simulation showing the growth of cosmic structure (galaxies and voids) when the universe was 0.9 billion, 3.2 billion and 13.7 billion years old (now). (Volker Springel/ MPE/Kavli Foundation)

Dark energy is whatever is causing the expansion of the Universe to accelerate. One of the most striking things about this mysterious energy is just how much ‘stuff’ in the Universe it accounts for. If you consider the contents of the cosmos to be matter and energy –more formally known as the Universe’s mass-energy density–then dark energy accounts for between 68% to 72% of all cosmic ‘stuff.’

Dark matter is the second-largest contributor, with just a tiny proportion of the Universe’s ‘stuff’ made up of the baryonic matter consisting of atoms that we see around us on a day-to-day basis.

This is even more staggering when you consider that all the stars, planets, dust, gas and cosmic bodies that make up the visible Universe are contained in this tiny fraction of cosmic stuff that doesn’t even amount to 5% of the Universe’s contents.

Dark energy could very roughly be described as a force acting in opposition to gravity. Whereas the more familiar everyday force of gravity holds objects like planets and stars together in orbits, dark energy acts as a repulsive force, driving galaxies themselves apart. But, whereas gravity acts upon objects themselves, dark energy acts on the very fabric of spacetime between objects. Because dark matter is the largest contributor to gravity, this means this mysterious substance is locked in what has been termed a ‘cosmic tug of war.’ And it’s clear during our current epoch, dark energy is winning!

A popular analogy for this is the description of the Universe as the surface of a balloon. Galaxies are represented by two marker ink dots on this surface. As the balloon is inflated the points move apart with the very space between them expanding.

Repeat the experiment with three unevenly placed dots and it is clear that the dots that are initially further apart recede away from each other more rapidly. This extremely rough analogy carries over to galaxies. The further apart the galaxies are, the more quickly they recede.

The expanding universe as the surface of a balloon (Bianchi, E., Rovelli, C. & Kolb, R. Is dark energy really a mystery?. Nature 466, 321–322 (2010). https://doi.org/10.1038/466321a)

An Expanding Surprise


The discovery that the Universe is expanding came as a considerable shock to the scientific community when it was confirmed by Edwin Hubble in 1929. Hubble had built upon theory provided by George Lemaitre and Alexander Friedman who had used the equations of general relativity to predict that the Universe was non-static, something that very much contradicted the scientific consensus of the time.

Ann Field STScl

Albert Einstein who devised general relativity had also found that his geometric theory of gravity predicted a non-static Universe, something he wasn’t exactly comfortable with. Despite having already killed many of the sacred cows of physics, Einstein was unwilling to do away with the concept of a static Universe. To recover a static Universe that was neither expanding nor contracting, the world’s most famous scientist introduced to his equations a ‘fudge factor’ called the cosmological constant–commonly represented with the Greek letter lambda.

The cosmological constant was in danger from the start. Once Hubble managed to persuade Einstein that the Universe was indeed expanding, the physicist abandoned the cosmological constant, allegedly describing it as his ‘greatest blunder’ in his later years. The cosmological constant wouldn’t stay in the cosmological dustbin for very long, however.

If physicists had been surprised by the discovery at the beginning of the 20th Century that the Universe is expanding, they would be blown away when at the end of that same century when the observations of distant supernovae made by two separate teams of astronomers revealed that not only is the Universe expanding, it is doing so at an accelerating rate.

To understand why this is shocking and how it leads to the conclusion that some repulsive force is driving this expansion, it is necessary to journey to the very beginning of time… Let’s take some balloons too…

Escaping the Big Crunch

A diagram of the expansion of the Universe. This accelerating expansion of the Universe could be explained by an early dark energy model. (NASA/ WMAP Team). Credit: NASA

When thinking about the initial expansion of the Universe it makes sense to conclude that the introduction of an attractive force within that Universe would slow and eventually halt this expansion. That is exactly what gravity should do, and it seems did do during the early stages of expansion that had nothing to do with dark energy (we think).

Some cosmologists are willing to go a step further. If there is no outward pressure but an inward attractive force, shouldn’t the Universe actually start to contract?

This leads to the theory that the Universe will end in what physicists term the ‘Big Crunch’–an idea that dark energy could make obsolete. Think about how counter-intuitive this was to scientists when the idea was first suggested and evidenced. Let’s return to the balloon analogy; imagine you stop blowing into the balloon, and instead start sucking the air out of it.

How shocked would you be to find that the balloon isn’t contracting, it’s continuing to expand? And not just that, it’s actually expanding faster than it was when you were blowing into it!

With that in mind, consider the initial moments of the Universe. Beginning in an indescribably dense and hot state, squeezed into a quantum speck, the Universe undergoes a period of rapid expansion. This period of expansion wasn’t driven by dark energy. As it expands, the Universe cools allowing electrons to form atoms with protons and neutrons, which in turn frees photons to travel the cosmos.

Soon there is enough matter in the Universe to allow the attractive force of gravity to slow its expansion. And this does seem to be what happened in the early cosmos. The rapid inflation of the infant Universe is believed to have halted at around 10 -32 seconds after the Big Bang, with the Universe still expanding, albeit at a much slower rate.

Euclid Assessment Study Report



This period of expansion continued to slow as a result of the growing dominance of matter during what cosmologists call the ‘matter-dominated epoch.’ But, at around 9.8 billion years into the Universe’s 13.8 billion year history, something strange begins to happen. The Universe begins to expand again, this time at an accelerating rate.

This is the dawn of the dark energy dominated epoch.

The Cosmological Constant is Back and Still Causing Trouble

Observations of the redshift of distant supernovae in the later 1990s showed cosmologists that not only was the Universe expanding, but it was doing so at an accelerating rate. (ESO)

That explains why the accelerating expansion of the Universe is so troubling and the need to introduce the placeholder concept of dark energy to explain it. Yet this accelerating expansion would still need a mathematical representation in equations used to describe the Universe. To do this cosmologists would return to the cosmological constant and its symbol, lambda.


This new iteration of the cosmological constant would be used in a different way to Einstein’s version. Whereas the earlier cosmological constant was used to balance gravity and hold the Universe steady and static, this new version would be used to overwhelm gravity and account for the acceleration of its expansion. But, this revised use of the cosmological constant does not mean it is any less troublesome than Einstein had found its predecessor.

In fact, the difference between the cosmological constant’s measured value, found by measuring the redshift of distant Type Ia supernovae, diverges from the value predicted by quantum field theory and particle physics by a value as large as 10121 (that’s 1 followed by 121 zeroes). Thus, it should come as no surprise that this value has been described as the worst prediction in the history of physics.

And as it represents the action of dark energy, that makes dark energy itself cosmology’s biggest conundrum.

OK… But What is Dark Energy?

So by now, you might well be thinking all of this is all fine and good, but this article specifically asks ‘what is dark energy?’ Isn’t it time to get to answering this question? It should come as no surprise that the answer is no one knows. But, that doesn’t mean that cosmologists don’t have some very good ideas.

One of the explanations for dark energy says that it could be vacuum energy, an underlying background energy that permeates that Universe and is represented by the cosmological constant. The most commonly cited evidence for vacuum energy–the energy of ’empty’ space which manifests as the Casimir effect.

Without delving too deeply into this, as relativity states that energy and mass are equivalent and mass has gravitational effects, then it stands to reason if empty space has vacuum energy, this too should contribute to the effect of gravity across the cosmos. That contribution has been factored in as a negative repulsive influence acting against the attractive influence of gravity.

Many explanations for dark energy exist, including the possibility that general relativity is incorrect and dark energy doesn’t exist at all.

The big problem with this is that quantum field theory suggests that this negative pressure contribution from vacuum energy should arise from all particles and thus, should give lambda a value that is tremendously larger than that obtain when our astronomers measure the redshift of Type Ia supernovae in distant galaxies.

This problem could be solved by dark energy’s effects being the result of something other than vacuum energy, of course. The Universe’s accelerating expansion could be due to some, as of yet undiscovered fundamental force of nature. Alternatively, it could indicate that our best current theory of gravity–general relativity– is incorrect.

A new generation of cosmologists is currently actively tackling the dark energy puzzle with new and revolutionary ideas. These include the idea that dark energy could have started work in the early Universe, an idea proposed by Early Dark Energy (EDE) models of the Universe. Another alternative is that dark energy does not influence the curvature of the Universe, or perhaps does so weakly–a theory referred to as the ‘well-behaved cosmological constant.’

As unsatisfying an answer as it is, the only honest way of addressing the question ‘what is dark energy?’ right now is by saying; we just don’t know. But, science wouldn’t be anywhere near as fascinating without mysteries to solve, and revolutionary ideas to be uncovered.

A look back at Hubble’s history in honor of its 30th anniversary

“Liftoff of the space shuttle Discovery, with the Hubble Space Telescope, our window on the universe,” were the words uttered by George Diller as STS-31 lifted off into a partly-cloudy Florida sky. That day — April 24, 1990 – was one, indeed, that would shape how we saw the unending expanse of space. The cargo aboard Discovery, 30 years ago, would end up becoming the most prolific space telescope in history and would change not only how we thought about the universe, but the creation of it itself.

Hubble Space Telescope was taken on the fifth servicing mission to the observatory in 2009. (Image: NASA)

The United States space program was still reeling from the Challenger explosion four years prior, and the launch of Hubble was not only a chance to learn more than ever about the universe, but a chance for NASA to remake its image with the public as well.

However, the story of Hubble started much earlier than that.

The road to Hubble

From the dawn of humankind to a mere 400 years ago, all that we knew about our universe came through observations with the naked eye. When Galileo turned his telescope toward the heavens in 1610, the world was in for an awakening.

Saturn, we learned, had rings. Jupiter had moons. That nebulous patch across the center of the sky called the Milky Way was not a cloud, but a collection of countless stars. Within but a few years, our notion of the natural world would be forever changed. A scientific and societal revolution quickly ensued.

In the centuries that followed, telescopes grew in size and complexity and, of course, power. They were placed on mountains far from city lights and as far above the haze of the atmosphere as possible. Edwin Hubble, for whom the Hubble Telescope is named, used the largest telescope of his day in the 1920s at the Mt. Wilson Observatory near Pasadena, California, to discover galaxies much further than our own.

During the 1970s, NASA and the European Space Agency (ESA) began planning for a space telescope that could transcend the blurring effects of the atmosphere and take clearer images of the Universe than ever before. The Hubble telescope was the first major optical telescope to be placed in space, the ultimate mountaintop. Without the atmosphere to hinder its observations, and far removed from rain clouds and light pollution, Hubble has an unobstructed view of the universe.

“Hubble is really a time machine,” said Larry Dunham, Hubble’s chief systems engineer at NASA’s Goddard Space Flight Center, in an interview. “We’re looking at data from light years in the past. Hubble is giving us the opportunity to look back in time to see how things were formed.”

Like every good love story, this one has its ups and downs with Hubble being the knot that ties the marriage of human curiosity and the science with satisfies it. Also, like a good marriage – and unlike most satellites – it gets better and stronger with age. Fifteen years after its expected lifespan, she has still not given up the ghost and has some of her most important discoveries just ahead.

The most marvelous part of the telescope, of course, is the 94.5-inch (2.4-meter-wide) mirror. As Eric Chaisson, an American astrophysicist and author wrote in his book The Hubble Wars, “While not the largest ever built, Hubble’s mirror is assuredly the cleanest and most finely polished mirror of its size. If Hubble’s mirror were scaled up to equal the width of the North American continent, the highest hill or lowest valley would be a mere few inches from the average surface.”

Up to a slow start

The mirror was also the headline when Hubble’s debut picture was snapped. Four weeks after leaving Discovery’s payload bay, the telescope’s initial offering to the public was that of a somewhat blurry photo of binary star HD96755, about 1,300 light-years away. A spherical aberration caused by a manufacturing error was causing the telescope to bring in only 10 to 15 percent of a star’s light into focus, as opposed to the 70 percent it should be gathering. Picture after picture revealed in no clearer images. Engineers eventually found that the shape of the concave mirror, moving from the center to the outer edge, was too shallow by up to two microns — 1/50 the width of a human hair.

Despite the flawed lens, Hubble was still able to take better pictures than any Earth-bound telescope (Image: NASA)

However slight, the error turned what was the most heralded telescope in NASA’s history into the laughingstock of the world. In fact, it wouldn’t be until December of 1993, three and a half years later, that the crew of Columbia would come to the rescue with a set of corrective optics to restore Hubble’s vision.

“The mirror flaw was a disappointment,” said Dunham. “It was really a disappointment that it showed up in the news. Even with the spherical aberration, the images we were getting were still better than anything we had ever had in the past.”

Replacing the mirror was not practical, so the best solution was to build replacement instruments that fixed the flaw much the same way a pair of glasses correct the vision of someone who is near-sighted. The corrective optics and new instruments were built and installed on Hubble by spacewalking astronauts during the STS-61 mission in 1993. The Corrective Optics Space Telescope Axial Replacement (COSTAR) instrument, which was about the size of a telephone booth, placed into Hubble five pairs of corrective mirrors that countered the effects of the flaw.

Kathryn Thornton replacing the solar arrays of the Hubble space telescope during the STS-61 mission (Image: NASA)

Once the mirror had a new set of spectacles, she now had the ability to look farther into universe than anything humans had ever produced. When astronomers pointed her to before had been an empty patch of sky in Ursa Major in 1995, they captured an image of over 3,000 galaxies too distant to be detected by other telescopes. (This was later called the Hubble Deep Field). Some of the galaxies Hubble found were so young, they had not yet begun serious star formation. Other deep field findings in the same area were performed, peering deeper into space each time. These were called the Hubble Ultra-Deep Field (released in 2004) and the Hubble eXtreme Deep Field (released in 2012). 

Besides the extraordinary finds, Hubble was famous for another reason. Unlike other satellites, Hubble was made into a better machine as time wore on. Each service mission would renew and improve her capabilities.

“With the servicing missions have allowed us to upgrade both the science instruments as well as the spacecraft hardware,” said Dunham. “Actually, it took us so long to get it up there initially (due to the delay after the Challenger explosion), that by the time we finally got Hubble up, a lot of its hardware was already obsolete. The recorders we launched with were tape, and now we have upgraded those to digital. The original computer we had was six-point binary assembly coding with a huge 32k of memory. Now we’ve got a 46 computer up there that has megabytes.”

Picture of the core of the galaxy M100 before and after the first servicing mission (Image: NASA)

In February 1997 the second servicing mission took place, resulting in the replacement of degrading spacecraft components, and the installation of new instruments such as the Space Telescope Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). STIS separated the light the telescope took in, and “dissected” it so that the composition, temperature, motion and other properties could be analyzed. With NICMOS, astronomers could see the first clear views of the universe at near-infrared wavelengths. 

On November 13, 1999, the fourth of six gyroscopes failed, and the telescope temporarily closed its eyes on the universe. Traveling at speeds of five miles per second, the gyros measure the spacecraft’s rate of motion and help point Hubble toward its observation target. Unable to conduct science without three working gyros, Hubble entered a state of safe mode dormancy. Essentially, Hubble took a nap while it waited for help. 

The third servicing mission was originally conceived as one of maintenance, but when the fourth gyro failed, NASA divided the work into two missions — and in the process, upheld the time-honored tradition of governments just making things more confusing by instead of calling them a third and fourth service mission, called them Servicing Mission 3A (SM3A) and Servicing Mission 3B (SM3B).

SM3A flew in December 1999 and the second in March 2002. During SM3A astronauts replaced all six gyroscopes with new ones, and installed a faster, more powerful main computer, a next-generation solid-state data recorder, a new transmitter, new insulation and other equipment. During SM3B, astronauts installed a new science instrument called the Advanced Camera for Surveys (ACS). ACS sees in wavelengths ranging from visible to far-ultraviolet, and can produce 10 times the science results in the same amount of time than the camera it replaced, the Faint Object Camera (FOC). 

Servicing Mission 4 (SM4), the fifth – and last — visit to Hubble, occurred in May 2009. Astronauts installed two new scientific instruments: the Cosmic Origins Spectrograph (COS) and Wide Field Camera 3 (WFC3). Two failed instruments, the Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys (ACS), were brought back to life by the first-ever on-orbit instrument repairs. In order to prolong Hubble’s life, other components were replaced including new batteries, new gyroscopes and a new science computer. In addition, a device was attached to the base of the telescope to facilitate de-orbiting when the telescope is eventually decommissioned. 

As things are now, that decommissioning date looks like it will be long in the future. Originally given a shelf life of 15 years, Dunham says that reentry of the satellite probably won’t occur until 2046, a 56-year span since it lifted off aboard Discovery. To put that in perspective, that is only five years less than when the telescope’s namesake reached his expiration date.

With the launch of the highly touted James Webb Telescope approaching nearer, the Hubble’s capabilities should only increase.“There are a lot of observations that people want to do in parallel with the Webb,” said Dunham. “The two spacecraft look at different light spectrums, so you can look at something with the Webb and get once sense of the object you’re looking at and then look at it with the Hubble and get another sense. Together you can produce some amazing science.”

Maybe it was appropriate that Discovery was the ship that took Hubble into orbit. The opportunities and discoveries we have made are more than the number of coins it took to produce it.

Famed poet Walt Whitman might have pegged it when he wrote:

“O to realize space!
The plenteous of all, that there are no bounds,
To emerge and be of the sky, of the sun and moon and flying clouds,
as one with them.”

Hubble’s spectacular new image of the Umbrella Galaxy will help make your quarantine prettier

Although things are getting pretty stressful here on Earth, it’s worth remembering that the universe is still an amazing place. A new image of the galaxy NGC 4651 captured by the Hubble Space Telescope is a great way to remind us of that.

The color image was made from separate exposures taken in the visible and near-infrared regions of the spectrum with Hubble’s Advanced Camera for Surveys (ACS) instrument.
Image credits NASA / ESA / Hubble / D. Leonard.

NGC 4651 sprawls about 93 million light-years away from our home, in the constellation of Coma Berenices — Latin for “Berenice’s Hair”. This group of stars is visible from both hemispheres and is the only constellation to be named after a historical figure.

The galaxy was first discovered by the German-born British astronomer William Herschel on December 30, 1783. But it hasn’t been seen in such exquisite detail ever before.

Pretty but dangerous

“NGC 4651 may look serene and peaceful as it swirls in the vast, silent emptiness of space, but don’t be fooled — it keeps a violent secret,” the Hubble team said. “It is believed that this galaxy consumed another smaller galaxy to become the large and beautiful spiral that we observe today.”

NGC 4651 is also known as the Umbrella Galaxy for the umbrella-like structure that extends some 100 thousand light-years beyond its disk. This bright structure is composed of tidal star streams — trails of starstuff that the galaxy’s gravitational pull stripped from a smaller satellite galaxy. This smaller galaxy has been completely devoured by NGC 4651 by this point.

I’ve marked the smaller galaxy’s remnant core — identified using data from the large Subaru and Keck telescopes on Mauna Kea — with a red line. It’s that tiny dot.
Image credits R. Jay GaBany via Wikimedia.

The team explains that this galaxy can be seen even with “an amateur telescope,” so if you do happen to have one on hand, that could help make your quarantine just a bit more bearable.

How fast is the universe expanding? We may need to recalculate

Our understanding of the universe may need some reconsidering, a new study suggests.

These galaxies are selected from a Hubble Space Telescope program to measure the expansion rate of the universe, called the Hubble constant. The value is calculated by comparing the galaxies’ distances to their apparent rate of recession away from Earth (due to the relativistic effects of expanding space). Credit: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey.

When Edwin Hubble announced that he discovered galaxies outside of our Milky Way, the announcement caused quite a stir — but this was just the beginning. Hubble found that galaxies which were farther away moved away faster from us. It wasn’t just galaxies either: anywhere he looked, he found the same thing: the farther things are, the faster they move apart from each other. This was undeniable evidence that not only was the universe expanding, but the expansion was accelerating.

The unit of measurement for this universal expansion is called the Hubble Constant.

The Hubble Constant is one of the most important numbers in modern physics because it describes a fundamental feature of our universe. But this rate of expansion is not easy to calculate. Most commonly, it is obtained by measuring the distance to distant galaxies and then calculating the redshift from these galaxies — in other words, by looking at how the wavelengths of light incoming from the galaxies are stretched. However, the different assumptions made in this calculation can strongly affect the result.

For the past century, astronomers have diligently measured the Hubble constant. In the 1990s, a team led by Wendy Freedman of the University of Chicago greatly refined the Hubble constant value to a precision of 10% — which was, fittingly, possible thanks to the Hubble telescope.

In more recent times, astronomers sought even higher precision. But the more they looked, the more they started to find discrepancies.

“Naturally, questions arise as to whether the discrepancy is coming from some aspect that astronomers don’t yet understand about the stars we’re measuring, or whether our cosmological model of the Universe is still incomplete,” University of Chicago astronomer Wendy Freedman said in a NASA press release.

“Or maybe both need to be improved upon.”

Recent studies have proposed somewhat different values for this universal expansion. Freedman’s most recent study, which has been accepted for publication in The Astrophysical Journal, sought to reconcile these values and serve as a tie-breaker — but instead, it added yet another value to be dealt with. According to what has been released so far, Freedman’s results indicate that the universe is expanding faster than most previous estimates. Their new observations, also made using Hubble, indicate that the expansion rate for the universe is just under 70 kilometers per second per megaparsec (km/sec/Mpc). One parsec is equivalent to 3.26 light-years distance, and a megaparsec is one million parsecs. This is one of the highest values for the universal expansion rate, but not the fastest — that one belongs to a team led by Adam Riess of the Johns Hopkins University and Space Telescope Science Institute, which found an expansion rate of 74 km/sec/Mp.

The differences are not trivial. Many modern cosmological concepts and calculations are based on the Hubble constant.

“The Hubble constant is the cosmological parameter that sets the absolute scale, size and age of the universe; it is one of the most direct ways we have of quantifying how the universe evolves,” said Freedman. “The discrepancy that we saw before has not gone away, but this new evidence suggests that the jury is still out on whether there is an immediate and compelling reason to believe that there is something fundamentally flawed in our current model of the universe.”

NASA’s upcoming mission, the Wide Field Infrared Survey Telescope (WFIRST), is expected to enable astronomers to calculate the Hubble constant even more accurately, also enabling researchers to calculate how this expansion rate changed through cosmic time. Needless to say, the mission, scheduled to launch in the mid-2020s, is eagerly awaited by the astronomic community.

Credit: ESA/Hubble & NASA.

Hubble finds ‘smiley face’ drawn by galactic objects

Credit: ESA/Hubble & NASA.

Credit: ESA/Hubble & NASA.

Outer space can be an intimidating and downright frightening thing to contemplate, which is why it helps to encounter a friendly face once in a while. In a new image captured by NASA’s Hubble Space Telescope, the elements of a galaxy cluster called SDSS J0952+3434 have aligned in such a way as to draw a smiley face many light-years across.

The ‘eyes’ of the smiley face are comprised of two yellow-hued blobs which hang atop a sweeping arc of light. The arc-shaped object is actually a galaxy whose shape has been distorted because its light passed near a massive object en route to Earth. This effect is known as gravitational lensing and requires that the three participants (the light source, the massive structure, and the observer — which is on Earth) be aligned in a straight-line configuration called a syzygy.

According to general relativity, light follows the curvature of spacetime. Consequently, when light passes around a massive object, it bends. This means that the light from an object on the other side will bend towards an observer’s eye, as it does through an ordinary lens. But unlike an optical lens, a gravitational lens has no single focal point, but a focal line. Scientists have been exploiting gravitational lensing — which is actually quite a common astronomical technique nowadays — in order to image distant cosmic objects that would have otherwise appeared as faint dots to our instruments.

Hubble stumbled across the friendly-looking galactic shape while it was searching for new stellar nurseries to study. Stars are born out of giant clouds of gas which eventually grow unstable, collapsing under gravity. Hubble’s Wide Field Camera 3 (WFC3) allows astronomers to analyze the luminosity, size, and formation rate of different stellar nurseries, which will one day allow them to understand the formation of new stars in finer detail than before. It’s important to study stellar formation within different galaxies to gain a richer context, which is why Hubble had its gaze fixed on a galaxy cluster.

NASA tries to fix Hubble problem by switching it off and on again

A solution that works far too often on Earth also seems to work off the ground.

Hubble is at it for 30 years — and it’s still going strong. Image: NASA.

You’ve never really used a computer unless you tried fixing something by switching it off and on again. It has an almost mystic quality to it, seeming to magically fix at least half of the common issues. But it doesn’t seem like something you’d try on a space telescope.

Hubble, one of the largest, most versatile, and most useful scientific instruments ever developed by mankind, has been in operation since 1990. Naturally, when you’re working in space for three decades, some things are bound to go wrong. Hubble is no stranger to wear and tear, being subjected to a few interventions over the years.

The most recent problem Hubble had was with one of its gyroscopes — devices that measure how fast the spacecraft is turning, and which essentially allow engineers to know where Hubble is looking at.

[panel style=”panel-default” title=”Gyro” footer=””]Hubble’s gyroscopes feature a wheel that spins at a constant 19,200 revolutions per minute. This wheel is mounted in a sealed cylinder, called a float. The float is suspended in a thick fluid.

Thin wires are immersed in the fluid, and they carry electricity to the motor. Electronics within the gyro detect very small movements of the axis of the wheel and communicate this information to Hubble’s central computer.

These gyros have two modes — high and low. High is used for coarse movements, whereas low is more of a high-precision mode.[/panel]

Hubble’s emblematic images have been a massive boon to astronomy and science in general. Image: NASA.

In an attempt to correct the malfunctioning gyro, the Hubble operations team restarted it — they switched it off for a second and then back on again. The gyroscope was also switched from high to low mode several times to clear any potential blockage in the fluid.

Initially, the data showed no improvement in the gyro’s performance. But after several switches, things started to improve. Hubble executed additional maneuvers to make sure that the gyro remained stable within operational limits as the spacecraft moved, and everything seemed to go along normally.

After additional engineering tests are completed, Hubble will return to its normal scientific activity.

Of course, it’s not as simple as saying that NASA just restarted Hubble and it worked — but it’s a bit funny how such a familiar approach (at least in principle) can work on anything from your old computer to one of the most complex machines ever built.

How many galaxies are there?

It’s impossible to know for sure, but Hubble revealed that there are at least 100 billion galaxies in the universe. However, this may be a conservative estimation — other estimates put the total number of galaxies at 2 trillion.

These are all galaxies, so here goes: one, two, three…
Image credits: Hubble.

What is a galaxy

Before we start looking for galaxies and counting them, we need to know just what a galaxy is.

Essentially, a galaxy is a huge collection of gas, dust, and billions of stars all tied together by gravity. Although the distances between stars within the same galaxy can be huge, it’s important that they’re all connected into a single cluster by gravity — that’s what makes it a galaxy. Most galaxies have a supermassive black hole at their center, which helps keep it all together. As the name implies, supermassive black holes are immensely massive black holes — they have a mass on the order of millions or even billions of solar masses.

There are three types of galaxies: elliptical, spiral, and irregular. The name pretty much describes the overall shape of the galaxy: elliptical galaxies look like an “egg” of light (an ellipse), spiral galaxies extend arms around the central bulge, and irregular galaxies are pretty much everything that’s not spiral or elliptical. The Milky Way, our own galaxy, is a spiral galaxy. It seems strange that complex and diverse systems such as galaxies take on such few shapes. Researchers are still not exactly sure why this happens, but these common shapes are likely the product of rotation speed, time and gravity.

The Pinwheel Galaxy, NGC 5457. A classic spiral galaxy. Image credits: Hubble.

Galaxies can also vary greatly in size, which means that some are more easily visible than others. Dwarf galaxies have between 100 million and several billion stars (a very small number compared to the Milky Way’s 200-400 billion stars), measuring “only” 300 light-years. Meanwhile, “IC 1101” is the single largest galaxy that has ever been found in the observable universe, spanning a whopping 210,000 light-years across.

Looking for galaxies

So how does one look for galaxies? We can all see (on clear nights) the bright, milk-ish band that lends our galaxy its name. More than 2,000 years ago, the Greek philosopher Democritus (450–370 BCE) proposed that the band might consist of distant stars, a surprisingly insightful idea. Of course, there are many things that Democritus couldn’t have known, and it wasn’t until 1610 when the Italian astronomer Galileo Galilei used a telescope to study the Milky Way and discovered that it is composed of a huge number of faint and very distant stars.

Fast forwarding to modern times, telescopes have obviously gotten a lot better. But one of the biggest problems for all telescopes is the atmosphere, which contains a lot of light pollution and distortion of electromagnetic radiation. Thankfully, astronomers have by-passed that problem by building space telescopes — yes, we have telescopes in outer space. The most famous one, although not the first, is the Hubble telescope. Hubble is a vital research tool which has provided an invaluable trove of data. Among others, the landmark Hubble Deep Field, taken in the mid-1990s, gave the first real insight into the universe’s galaxy population.

The Antennae Galaxies, featured here, will eventually merge. Image credits: Hubble.

But even with Hubble, counting galaxies is extremely difficult for the simple fact that the universe is, well, very big. Looking in all directions and counting all the galaxies is nigh impossible, so instead, astronomers just focus on a sector of the night sky, count the galaxies there, and extrapolate based on that value. Of course, this can lead to some inaccuracies, but given the sheer size of the universe and the number of galaxies, the inaccuracies are unlikely to be significant.

How many galaxies are there

So, back to the question: how many galaxies are there? The first measurements from the 1990s found that there are 200 billion galaxies in the universe. However, that figure is unlikely to be reliable. Subsequent sensitive observations found that many faint galaxies were not observed the first time. The most recent, and likely the most accurate, survey found that the real number of galaxies is ten times larger: so, in total, there are 2 trillion galaxies in the universe, or 2,000 billion, if you prefer.

In late 2016, Christopher Conselice, Professor of Astrophysics at the University of Nottingham, along with several colleagues, carried out a sort of archaeological cosmology: they calculated the density of galaxies as well as the volume of one small region of space after another. This painstaking research was the culmination of 15 years of research, and it enabled the team to establish how many galaxies we have missed. The team found that, initially, astronomers missed a lot of galaxies because they were faint and very far away.

“We are missing the vast majority of galaxies because they are very faint and far away. The number of galaxies in the universe is a fundamental question in astronomy, and it boggles the mind that over 90% of the galaxies in the cosmos have yet to be studied. Who knows what interesting properties we will find when we study these galaxies with the next generation of telescopes?”

Each light speck is a galaxy, some of which are as old as 13.2 billion years. The universe is estimated to contain anywhere between 200 billion and 2 trillion galaxies. Image credits: Hubble.

Since many of the very distant galaxies are also faint, it seems that the total number of galaxies is currently decreasing over time. However, the more important takeaway lesson here is that we’re still only seeing a very small portion of the universe. Who knows what we might be missing out on. The study also says that the real number of galaxies might be even higher — up to 10 trillion galaxies.

“It boggles the mind that over 90% of the galaxies in the universe have yet to be studied,” commented Conselice. “Who knows what interesting properties we will find when we observe these galaxies with the next generation of telescopes?” he said in a statement.

Bonus: How many planets are there in the Universe?

If you’re still trying to wrap your mind around the number of galaxies, here’s another one. Estimating how many planets there are in the universe is much more a ballpark figure, and relies much more on deduction than direct observation. But for the fun of it, let’s do some simple math. Let’s say there are 2 trillion galaxies out there. The Milky Way is a fairly average galaxy, and it has over 200 billion planets. If we extrapolate based on that, we end up with 400 billion trillion planets in the universe. That’s 400,000,000,000,000,000,000,000 planets.

Again, this is definitely an approximation and not scientifically accurate, but it’s something to consider when you feel like you’re pretty important.

Hubble completes the most complete ultraviolet-light survey of nearby galaxies — and the photos are mind blowing

Galaxies are amazing things, and we can now see some of them in unprecedented detail.

The spiral galaxy Messier 96 lies some 35 million light-years away. Image credits: NASA, ESA, and the LEGUS TEAM.

“There has never before been a star cluster and a stellar catalog that included observations in ultraviolet light,” explained survey leader Daniela Calzetti of the University of Massachusetts, Amherst. “Ultraviolet light is a major tracer of the youngest and hottest star populations, which astronomers need to derive the ages of stars and get a complete stellar history. The synergy of the two catalogs combined offers an unprecedented potential for understanding star formation.”

Light comes in different wavelengths. Ultraviolet light (UV) has a shorter wavelength than that of visible light, but longer than X-rays, and UV constitutes about 10% of the total light output of stars like the Sun. When you “look” at something in different wavelengths, you can infer different things about its physical properties. In this case, astronomers were trying to learn more about star formation, a process that still holds many secrets.

Astronomers combined new and old Hubble observations, looking for detailed information on young, massive stars and star clusters, as well as their evolution. It’s ironic, really — almost all we know about the universe, we know thanks to light from stars, and yet we don’t know how the stars themselves form.

The spiral galaxy Messier 66. Image credits: NASA, ESA, AND THE LEGUS TEAM.

As far as we know, stars form inside relatively dense concentrations of interstellar gas and dust known as molecular clouds. These areas are extremely cold (just ten degrees K above absolute zero), and at those temperatures, gases become molecular, meaning they’re much more likely to bind together. Oftentimes, gases clump up to higher and higher densities, and once a specific point is passed, stars can form. But here’s the thing: before the star is actually formed, the region is very dense and dark, virtually opaque to visible light (something called a dark nebula). Astronomers can still investigate them to an extent, but they use infrared and radio telescopes. So, instead, researchers try to find very young stars.

The research team carefully selected the LEGUS targets from among 500 galaxies, all of which lie between 11 million and 58 million light-years from Earth. Team members chose the galaxies based on their mass, star-formation rate, and abundances of metals –which, in this context, means elements that are heavier than hydrogen and helium.

Galaxies come in multiple shapes and sizes. We tend to think of galaxies as being spiral, Milky Way-like structures, but galaxies can be quite varied in terms of shape and size. Stars tend to be distributed quite regularly in galaxies, but while groups of stars tend to be more predictable, the same can’t be said about individual stars.

“When we look at a spiral galaxy, we usually don’t just see a random distribution of stars,” Calzetti said. “It’s a very orderly structure, whether it’s spiral arms or rings, and that’s particularly true with the youngest stellar populations. On the other hand, there are multiple competing theories to connect the individual stars in individual star clusters to these ordered structures.

These six images represent the variety of star-forming regions in nearby galaxies. The galaxies are part of the Hubble Space Telescope’s Legacy ExtraGalactic UV Survey (LEGUS), the sharpest, most comprehensive ultraviolet-light survey of star-forming galaxies in the nearby universe. The six images consist of two dwarf galaxies (UGC 5340 and UGCA 281) and four large spiral galaxies (NGC 3368, NGC 3627, NGC 6744, and NGC 4258). The images are a blend of ultraviolet light and visible light from Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys. Image credits: NASA/ESA/LEGUS team.

This is where the new survey comes in, and why it’s so important. By imaging the galaxies in such detail, astronomers are able to zoom in on individual star populations, thus gaining more information about them. We can almost certainly expect a flurry of studies on star formation in the near future.

“By seeing galaxies in very fine detail — the star clusters — while also showing the connection to the larger structures, we are trying to identify the physical parameters underlying this ordering of stellar populations within galaxies. Getting the final link between gas and star formation is key for understanding galaxy evolution,” Calzetti concludes.

 

Five Reasons Why We Should be Exploring Space

If you’ve ever found yourself under a bright starry sky on a clear night, you probably noticed the splendor that is space. For millennia, man has cast his gaze towards the heavens and wondered what’s out there. For some, that quote serves as both the question and justification for continuing to cast our gaze deeper and deeper into space.

Credit: NASA.

Some people don’t even bother. For them, the answer to that question is a resounding ‘who cares?’. So why bother with exploring space? There is a myriad of reasons but it would take too long to go through all of them, so we’ve broken them down into five reasons: we learn, we push, we discover, we benefit, we evolve.

Curiosity

Mankind has demonstrated time and again an insatiable curiosity and the need to satisfy that curiosity. Explorers have always sailed the wide ocean in the search for new lands. Sir Edmond Hillary scaled Mt. Everest. Magellan circumnavigated the globe in a ship. Yuri Gagarin and Neil Armstrong first pushed the limits of humans into space.

Humans push the limits of what we can do — it’s in our very nature. If you think about it, children push their own limits every single day. They learn new things and expand their horizon.  Space exploration is, in a way, turning back to that childhood curiosity. Every day, we learn new things about the universe around us. However, humans have no idea what our limits are in space, so we keep pushing, and we keep learning.

Credit: NASA.

With every boundary, we learn new things: how humans deal with extended time in space, the physical composition of the moon, how to fix a toilet in zero gravity, how to grow food in space, the location of black holes, recycling water and oxygen in space and (finally) how to break free of our gravitational limits and move forward.

Scientific

With the launch of the Hubble Space Telescope, humans took a quantum leap into the exploration of space that rivaled Galileo when he probed the skies in the late 1500s. The images the Hubble telescope have allowed us to peer deeper into space than anyone could have ever imagined (seriously, check those images out).

Pointed at a supposedly blank portion of the sky, about the size of a pinprick, seemingly bereft of anything interesting, Hubble gave us images that changed our understanding of the universe. Tens of thousands of galaxies, many like our own, each with trillions of stars and at least as many planets. Now multiply that by the number of “pinpricks” in the night sky and you now have some idea of just how vast the cosmos truly is.

It’s not just about space, either: the International Space Station carries out numerous experiments, from biology to hard physics. Credit: NASA.

Financial

Eventually, humans will figure a way into space and utilize the infinite resources it promises. The development of space will make fortunes for those brave (and lucky) enough to take the plunge. These new-found resources will certainly be the source of significant benefits for those of us who remain firmly planted on terra firma.

It will also signify that man has evolved enough to perhaps establish a permanent extra-terrestrial habitat. A century ago, WWI was winding down. Cars, indoor plumbing, electricity, and refrigeration were luxuries (or non-existent). Now, we have airplanes, smartphones, space travel, and computers.

Continuing that progression, the idea of colonizing the moon, Mars or moons of the gas giants shouldn’t be that far-fetched. It’s the natural progression/evolution of our species.

Five reasons to explore space? We learn, we push, we discover, we benefit and we evolve. That’s why.

Now go back and check that Hubble link!!

A patch of the sky captured by the Hubble Space Telescope shows thousands of galaxies stretched over billions of light years. Only 10 percent of galaxies are observable with telescopes, according to the Great Observatories Origins Deep Survey (GOODS).

Latest census finds ten times more galaxies in the Universe — that’s nearly two trillion

A patch of the sky captured by the Hubble Space Telescope shows thousands of galaxies stretched over billions of light years. Only 10 percent of galaxies are observable with telescopes, according to the Great Observatories Origins Deep Survey (GOODS).

A patch of the sky captured by the Hubble Space Telescope shows thousands of galaxies stretched over billions of light years. Only 10 percent of galaxies are observable with telescopes, according to the Great Observatories Origins Deep Survey (GOODS).

Surveys taken by NASA’s Hubble Space Telescope and other observatories found the universe is a lot more crowded than we previously thought. At least ten times more galaxies were found in our galactic field of vision or nearly two trillion.

More mind-boggling than ever

Christopher Conselice of the University of Nottingham, U.K., led the team of astronomers who made the galactic tally. Most of the new additions were small and faint galaxies, very similar to the satellite galaxies that hover about the Milky Way, our galactic neighborhood. In the course of their evolution, many of these faint galaxies merge to form larger populations, dwindling the densities of galaxies in space. It follows that galaxies aren’t evenly distributed throughout the universe’s history, an important find with many implications in astrophysics.

“These results are powerful evidence that a significant galaxy evolution has taken place throughout the universe’s history, which dramatically reduced the number of galaxies through mergers between them — thus reducing their total number. This gives us a verification of the so-called top-down formation of structure in the universe,” explained Conselice.

To count the galaxies, Conselice and colleagues used deep-space imaging from Hubble and previously published data from other teams. These images had to be converted into 3-D so they could make accurate measurements of the number of galaxies at the different epoch in the history of the universe. If it took a million years for light emitted from a galaxy to reach us, we can learn what it looked like at that time but we don’t know how it looks like now.

Mathematical models then crunched through the number to infer the existence of galaxies otherwise unobservable through direct means. Ultimately, for the number of galaxies and their masses to add up, there have to be a lot more faint and distant galaxies that can’t be imaged with present-day telescopes. This myriad of dwarf galaxies merged over time into the behemoths we can see today, the team reported in the Astrophysical Journal.

“It boggles the mind that over 90 percent of the galaxies in the universe have yet to be studied. Who knows what interesting properties we will find when we discover these galaxies with future generations of telescopes? In the near future, the James Webb Space Telescope will be able to study these ultra-faint galaxies,” said Conselice.

This latest survey also helps explain an age-old conundrum, Olbers’ paradox. In the 1800s, German astronomer Heinrich Wilhelm Olbers wondered why the sky was so dark at night if the universe holds a virtually infinite number of stars. Conselice explains that there is indeed such an immense bounty of galaxies that every patch in the sky contains at least one galaxy. However, the light is so faint that the galaxies are invisible not only to the naked eye but high-end telescopes as well. Then, there’s the issue of the reddening of light, known as red-shift, due to the universe’s expansion. Interstellar dust and gas also absorb much of this distant light, explaining why the night’s sky stays so dark.

The Universe is expanding faster than we thought, new Hubble study finds

Astronomers working with the Hubble telescope have discovered that the Universe is expanding 5-9% faster than expected, and this is intriguing.

This illustration shows the three steps astronomers used to measure the universe’s expansion rate to an unprecedented accuracy, reducing the total uncertainty to 2.4 percent. Astronomers made the measurements by streamlining and strengthening the construction of the cosmic distance ladder, which is used to measure accurate distances to galaxies near and far from Earth. Credit: NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU)

Even though it’s a well documented phenomenon, universal expansion is still baffling. The entire universe, every single thing that we know of is moving apart – and it’s accelerating! That’s just crazy when you think about it. The fact that we can measure how fast it’s expanding is even crazier.

In theory, you could measure the expansion of the universe could by taking a standard ruler and measuring the distance between two cosmologically distant points, waiting a certain time, and then measuring the distance again, but in practice, you’re never going to have a cosmological ruler, and time isn’t really on your side either. So astronomers are using other indirect methods, which of course come with an associated error. Such an error was corrected this time, and it came as quite a surprise.

“This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95 percent of everything and don’t emit light, such as dark energy, dark matter, and dark radiation,” said study leader and Nobel Laureate Adam Riess of the Space Telescope Science Institute and The Johns Hopkins University, both in Baltimore, Maryland.

He an his team refined the measurement and managed to reduce the uncertainty to only 2.4 percent. They measured about 2,400 Cepheid stars (stars that pulsate radially) in 19 galaxies and compared the observed brightness of the stars. Cepheid stars pulsate at rates that correspond to their true brightness, which can be compared with their apparent brightness as seen from Earth to accurately determine their distance.

The new constant value they found 73.2 kilometers per second per megaparsec. (A megaparsec equals 3.26 million light-years.) This means that the distance between cosmic objects will double in another 9.8 billion years. We still don’t know what is the cause for the initial error, but one of the likely culprits is dark energy, already known to be accelerating the universe. Another possible explanation is an unexpected characteristic of dark matter. Dark matter is the backbone of the universe upon which galaxies built themselves up into the large-scale structures seen today.

“If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the big bang and use that understanding to predict how fast the universe should be expanding today,” said Riess. “However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today.”

 

NASA snaps beautiful picture of Mars as it inches over towards Earth

NASA astronomers captured a beautiful image of Mars on May 12, when the planet was just 50 million miles away from Earth. Bright snow-capped polar regions and rolling clouds above the rusty landscape show that Mars is a dynamic, seasonal planet, not an inert rock barreling through space.

This picture was taken just a few days before the Mars opposition on May 22, when the red planet and the sun will be on exact opposite side of the Earth. Mars circles around the sun on an elliptical orbit, and its approaches to Earth range from 35 to 63 million miles. From now to May 30 Mars will inch in ever closer to 46.8 million miles from us — the closest this planet has been to Earth for the last 11 years. Being illuminated directly by the sun, Mars is especially photogenic and NASA used this opportunity to capture a beautiful shot of the planet.

The most eye-catching features are the thick blankets of clouds, clinging to the planet’s thin atmosphere. They can be seen covering large parts of the planet, including the southern polar cap. The western limbs are early morning clouds and haze, while the eastern part is an afternoon cloud extending for more than 1,000 miles at mid-northern latitudes. The northern polar cap is barely visible, as it’s now late summer in that hemisphere.
Mars Near 2016 Oppostion (Annotated)

The overcast Syrtis Major Planitia is an ancient shield volcano, now inactive. It was one of the first structures charted on the planet’s surface by seventeenth century observers. Huygens used this feature as a reference point to calculate the rotation speed of Mars — one day on the red planet clocking in at 24 hours and 37 minutes.

Hellas Planitia basin extends to the south of Syrtis Major. At about 1,100 miles across and nearly five miles deep, you’d think it’s a tectonic depression, but it was actually formed 3.5 billion years ago when a huge asteroid crashed into Mars. The planet had its fair share of meteorite impacts throughout the ages, as Arabia Terra can attest — this 2,800 mile upland region is dotted with craters and heavily eroded. Dry river canyons wind through the region, testament to rivers that once flowed into the large northern lowlands.

The long, dark ridges running along the equator south of Arabia Terra, are known as Sinus Sabaeus (to the east, not pictured) and Sinus Meridiani (to the west). These areas are covered by dark bedrock and sand ground down from ancient lava flows and other volcanic features. The sand is coarser and less reflective than the fine dust enveloping the planet, making them stand out.

Several NASA Mars robotic missions, including Viking 1 (1976), Mars Pathfinder (1997) and the still-operating Opportunity Mars rover have landed on the hemisphere visible in this picture. Spirit and Curiosity Mars rovers landed on the opposite side of the planet.

All images provided by Hubble Site.

Hubble captures the death of a star, offering a glimpse of our sun’s final days

A spectacular image captured by the Hubble Space Telescope’s Wide Field Planetary Camera 2 (WFPC2) gives us a glimpse into how the Sun will look at its death.

Launched in 1990, the Hubble Space Telescope is among the most powerful and versatile tools astronomers have at their disposal even to this day. On Monday, the European Space Agency released a photo taken bu Hubble’s WFPC2 of the planetary nebula Kohoutek 4-55 that reminds us that nothing under the sun lasts forever — but the star itself also abides by that saying.

Five billion years from now, this is most likely how the sun will look. By then, the star is anticipated to be on the throes of death.
(Photo : NASA, ESA and the Hubble Heritage Team (STScI/AURA). Acknowledgment: R. Sahai and J. Trauger (JPL))

This photo is a composite image of three individual shots taken at specific wavelengths, to allow researchers to distinguish light from particular gas atoms. The red wavelength corresponds to nitrogen gas, blue to oxygen and green signifies hydrogen.

At the center of the colorful swirl of gas is a star, about the same size as the sun, on the throes of death. The star is about as massive as the sun. As stars age and consume their fuel, the nuclear reactions that produces their light and warmth start to slow down; The irregular energy patterns of energy production causes aging stars to pulsate irregularly making them eject their outer layers.

As the outer layers of gases are released the star’s core is revealed, giving of massive amounts of UV light. That radiation is responsible for the glow of the gas and the nebula’s beauty.

The sun is anticipated to behave in a similar manner to the Kohoutek 4-55 star,ejecting its outer layers to reveal its core — until it gradually cools down into a white dwarf. The image allows scientists a glimpse the distant future of our sun, expected to die off 5 billion years from now.

“By that time, Earth will be long gone, burnt to a crisp as the Sun dies,” ESA wrote. “But the beauty of our star’s passing will shine across the Universe.”

Hubble’s ‘heir’ is coming together

NASA is very close to reaching a milestone in the construction of the James Webb Space Telescope (JWST), Hubble’s successor that will be launched in 2018.

The telescope will consist of 18 mirror segments when it’s completed. Each segment can be independently adjusted to bring the starlight into focus.
David Higginbotham/Emmett Given/MSFC/NASA

Engineers have almost completely assembled the giant mirror, with a collecting area about five times larger (25 square meters) than Hubble’s – despite being twice as light. When complete, the mirror will look like a giant satellite dish – one that’s two stories high.

“So far, everything — knock on wood — is going quite well,” says Bill Ochs, the telescope’s project manager at Goddard Space Flight Center in Maryland.

Comparison between Hubble’s and James Webb’s mirrors. Wikipedia.

This has been the fastest and most cursive part of the building schedule in what was otherwise a project with many hurdles and delays. This isn’t unexpected though. When Hubble’s construction started in 1972, it had an estimated cost of $300 million – but when it finally went in space in 1990, it cost four times more. But just like Hubble was revolutionary (and still is), so too will James Webb be.

The largest NASA astrophysics mission of its generation, JWST will offer unprecedented resolution and sensitivity from long-wavelength (orange-red) visible light, through near-infrared to the mid-infrared. It will be able to capture light from the first stars and galaxies in the Universe, from billions of light years across.

It will also probe the atmospheres of potentially habitable planets, providing more information on their habitability. It’s bigger and better.

“Every time we build bigger or better pieces of equipment, we find something astonishing,” he says.

Full scale James Webb Space Telescope model at South by Southwest in Austin. Wikipedia.

Unfortunately, the construction of something so large and innovative is bound to have some delays and cost extensions. The first estimates suggested the observatory would cost $1.6 billion and launch in 2011. Now, NASA has scheduled the telescope for a 2018 launch and that seems to be well on track. They even have a generous margin for an October 2018 launch.

“We keep our fingers crossed, but things have been going tremendously well,” said Nasa’s JWST deputy project manager John Durning. “We have eight months of reserve; we’ve consumed about a month with various activities,” he added.

Pillars of Creation

3D map of the Pillars of Creation shows the same shaping forces will also destroy them

Using the MUSE instrument aboard  ESO’s Very Large Telescope (VLT), astronomers have made a three dimensional view of the famous Pillars of Creation – a photograph taken by Hubble 20 years ago showing elephant trunks of interstellar gas and dust in the Eagle Nebula, some 7,000 light years from Earth. The 3D image shows never before seen details of the dust columns, greatly expanding scientists’ knowledge of how these formed, but also what’s in stored for them in the future.

Pillars of Creation

A 3-D map of the Pillars of Creation. ESO/VLT

These beautiful features were born out of the intense energy spewed by new stars in the Eagle Nebula. It’s actually a classic example column-like shapes that develop in the giant clouds of gas and dust nearby newborn stars.

The original 1995 image was beautiful. Compare this view to the 2014 image in a side-by-side montage. Image: NASA

The original 1995 image was beautiful. Compare this view to the 2014 image in a side-by-side montage. Image: NASA

The same stars that formed the pillars will also destroy them, however. On one side, the ultraviolet radiation and stellar winds gushing from freshly formed blue-white O and B stars blow away less dense materials from their vicinity, causing the pillars to form in the place. On the other side, however, the same radiation is breaking up the gas and dust columns. Denser pockets act like a shield and protect less dense regions from destruction, but not forever. Using this new data, astronomers operating the Very Large Telescope  estimate the pillars lose roughly 70 times the mass of the sun every million years. This would entail that the Pillars of Creation only have three million years left before they’re obliterated. It’ll be only the Pillars of Destruction that remain in the aftermath.

The new study also reports fresh evidence for two gestating stars in the left and middle pillars as well as a jet from a young star that had escaped attention up to now, as reported in Monthly Notices of the Royal Astronomical Society.

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Most detailed picture EVER of a new planet being born

Some 450 light-years away in the constellation Taurus, a new planet is being born and astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile were there to capture the moment. It’s the most detailed picture documenting a planetary-forming system.

The cutest planetary baby picture

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Protoplanetary disc surrounding the young star HL Tau. ALMA (ESO/NAOJ/NRAO)

“This is truly one of the most remarkable images ever seen at these wavelengths,” Dr. Crystal Brogan, an astronomer at the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, said in a written statement. “The level of detail is so exquisite that it’s even more impressive than many optical images.”

When NASA or other agencies release pictures like these, they’re usually simulations or visual renditions of computer models. The most beautiful are actually artist made illustrations. This image, however, is the real deal.

HL Tau's neighborhood, courtesy of Hubble. Image: ALMA (ESO/NAOJ/NRAO), ESA/Hubble and NASA

HL Tau’s neighborhood, courtesy of Hubble. Image: ALMA (ESO/NAOJ/NRAO), ESA/Hubble and NASA

More specifically, it features the star HL Tau surrounded by an envelope of gas and dust called an accretion disk. See those gaps in the image? This is where new planets will be formed, as gas and dust are cleared from their orbit.

“These features are almost certainly the result of young planet-like bodies that are being formed in the disk,” ALMA Deputy Director Dr. Stuartt Corder said in the statement. “This is surprising since HL Tau is no more than a million years old and such young stars are not expected to have large planetary bodies capable of producing the structures we see in this image.”

[ALSO SEE] Astronomers upset the theory of planetary formation

In the past half-decade, we’ve learned about thousands of planets throughout the galaxy, but we still don’t really know what turns young, spinning baby stars into stable solar systems. In fact, there are multiple theories that try to explain how planets form. The most accepted of these says that the enormous discs that surround baby stars collide and accrete into planet-sized objects. The matter inside the rapidly spinning disk around the parent star starts to gather and form clumps, steadily accumulating until these turn into asteroids, comets, planets and moons. As these get bigger, the objects plow through the accretion disk which is why we see gaps in this latest picture reported by ALMA.

See an artist’s animation below to learn more about planet formation.

Horse Head nebula

Stunning Horsehead nebula imaged in infrared

Horse Head nebula

Two fantastic space telescopes, Hubble and ESA’s Herschel, have teamed up to image one of the most popular astronomical sights in the sky, the “Horsehead” nebula, in infrared  as well as longer wavelengths to provide unprecedented insights as to what’s going on in this stunning star hatchery.

Listed in catalogues under “Barnard 33”, but better known as the Horsehead nebula thanks to its distinctive shape, this fabulous molecular gas cloud lies some 1,300 light years away in the constellation Orion. Until recently, optical observations have made the nebula famous, but new infrared imaging shows the Horsehead in unprecedented detail.

Besides being a fabulous sight, the region is also a highly active star formation region, which makes it particularly appealing.

“You need images at all scales and at all wavelengths in astronomy in order to understand the big picture and the small detail,” said Prof Matt Griffin, the principal investigator on Herschel’s SPIRE instrument.

“In this new Herschel view, the Horsehead looks like a little feature – a pimple. In reality, of course, it is a very large entity in its own right, but in this great sweep of a picture from Herschel you can see that the nebula is set within an even larger, molecular-cloud complex where there is a huge amount of material and a great range of conditions,” the Cardiff University, UK, researcher told BBC News.

The image comes ahead of the 23rd anniversary of the telescope’s launch on the space shuttle Discovery on April 24, 1990. Its successor, the James Webb Space Telescope, is due to launch around 2018.

Hubble takes brilliant picture of young star population in elderly company

The great pics from Hubble just never end! This time, the brave telescope offered an impressive view of the center of globular cluster NGC 6362. The image of this spherical collection of stars takes a deeper look at the core of the globular cluster, which contains a high concentration of stars with different colors.

Click the pic for full size.

Seeing what appears to be young stars came as quite a surprise, considering that globular clusters are composed of old stars, which, at around 10 billion years old, are way older than the Sun. These clusters are quite common both in our galaxy (over 150 found so far) and in other galaxies. Also, globular clusters are among the oldest objects directly observable in the known Universe, making them living fossils, extremely useful in understanding how galaxies work.

The accepted theory at the moment is that all stars in a globular cluster are about the same age; however, new, high precision measurements performed in numerous globular clusters, primarily with the Hubble Space Telescope have made some astrophysicists doubt this theory. In particular, there appear to be younger, bluer stars, amidst older ones. Researchers dubbed them blue stragglers and NGC 6362 has lots of them.

It’s unclear at the moment how they appear, but since they are usually found in the core regions of clusters, where the concentration of stars is large, the most plausible explanation seems to be that they form as a result of stellar collisions or transfer of material between stars in binary systems.

NGC 6362 is located about 25 000 light-years from Earth in the constellation of Ara (The Altar), and it was discovered all the way back in 1826 by British astronomer James Dunlop.