Tag Archives: Space

Researchers have just found the biggest galaxy ever discovered — and it’s big alright

The distance from the Sun to Pluto, the farthest planet(oid), is 0.000628 light-years. The closest solar system to us, Alpha Centauri, is 4.2 light-years away. The Milky Way Galaxy is 52,850 light-years across. But Alcyoneus, the newly-discovered galaxy, is a whopping 16.3 million light-years wide.

Giant radio galaxies (GRGs, or just ‘giants’) are the Universe’s largest structures generated by individual galaxies. They were first discovered accidentally by wartime radar engineers in the 1940s, but it took over a decade to truly understand what they were — with the aid of radio astronomy. Radio astronomy is a subfield of astronomy that studies celestial objects using radio frequencies.

These giants dominate the night sky with their radio frequency signals (astronomers use different types of frequencies to study the universe). They generally consist of a host galaxy — a cluster of stars orbiting a bright galactic nucleus containing a black hole — and some colossal jets or lobes that erupt from this galactic center.

Most commonly, radio galaxies have two elongated, fairly symmetrical lobes. These radio lobes are pretty common across many galaxies — even the Milky Way has them — but for some reason, in some galaxies, the lobes grow to be immensely long. Discovering new radio galaxies could help us understand these processes — this is where the new study comes in.

Researchers led by astronomer Martijn Oei of Leiden Observatory in the Netherlands have discovered the largest single structure of galactic origin. They used the LOw Frequency ARray (LOFAR) in Europe, a network of over 20,000 radio antennas distributed across Europe.

“If there exist host galaxy characteristics that are an important cause for giant radio galaxy growth, then the hosts of the largest giant radio galaxies are likely to possess them,” the researchers explain in their preprint paper, which has been accepted for publication in Astronomy & Astrophysics.

The lobes of the newly-discovered galaxy. Image credits: Oei et al (2022).

According to the authors, this is the most detailed search ever of radio galaxy lobes, and lo and behold, the results also came in.

Alcyoneus lies some 3 billion light-years away from us, a distance that’s hard to even contemplate (though it’s not nearly the farthest object we’ve found, which lies over 13 billion light-years away). Its host galaxy appears to be a fairly normal elliptical galaxy. In fact, it almost seems too inconspicuous.

But even this could tell us something: you don’t need a particularly large galaxy or a particularly massive black hole at its center to create a radio galaxy.

“Beyond geometry, Alcyoneus and its host are suspiciously ordinary: the total low-frequency luminosity density, stellar mass and supermassive black hole mass are all lower than, though similar to, those of the medial giant radio galaxies,” the researchers write.

“Thus, very massive galaxies or central black holes are not necessary to grow large giants, and, if the observed state is representative of the source over its lifetime, neither is high radio power.”

The study has been published in arXiv.

Earth might develop ‘junk’ rings — but engineers are working to prevent that

Earth may one day have its own ring system — one made from space junk.

Rendering of man-made objects in Earth’s orbit. Image via ESA.

Whenever there are humans, pollution seems to follow. Our planet’s orbit doesn’t seem to be an exception. However, not all is lost yet! Research at the University of Utah is exploring novel ideas for how to clear the build-up before it can cause more trouble for space-faring vessels and their crews.

Their idea involves using a magnetic tractor beam to capture and remove debris orbiting the Earth.

Don’t put a ring on it

“Earth is on course to have its own rings,” says University of Utah professor of mechanical engineering Jake Abbott, corresponding author of the study, for the Salt Lake Tribune. “They’ll just be made of space junk.”

The Earth is on its way to becoming the fifth planet in the Solar System to gain planetary rings. However, unlike the rock-and-ice rings of Jupiter, Saturn, Neptune, and Uranus, Earth’s rings will be made of scrap and junk. It would also be wholly human-made.

According to NASA’s Orbital Debris Program Office, there are an estimated 23,000 pieces of orbital debris larger than a softball; these are joined by a few hundreds of millions of pieces smaller than a softball. These travel at speeds of 17,500 mph (28,160 km/h), and pose an immense threat to satellites, space travel, and hamper research efforts.

Because of their high speeds, removing these pieces of space debris is very risky — and hard to pull off.

“Most of that junk is spinning,” Abbott added. “Reach out to stop it with a robotic arm, you’ll break the arm and create more debris.”

A small part of this debris — around 200 to 400 — burns out in the Earth’s atmosphere every year. However, fresh pieces make their way into orbit as the planet’s orbit is increasingly used and traversed. Plans by private entities to launch thousands of new satellites in the coming years will only make the problem worse.

Abbott’s team proposes using a magnetic device to capture or pull debris down into low orbit, where they will eventually burn up in the Earth’s atmosphere.

“We’ve basically created the world’s first tractor beam,” he told Salt Lake Tribune. “It’s just a question of engineering now. Building and launching it.”

The paper “Dexterous magnetic manipulation of conductive non-magnetic objects” has been published in the journal Nature.

What is the Oort cloud: the very edge of the solar system

Every system needs a boundary, and the Solar System is no different. Although we haven’t been able to physically reach and see it, we have a theory about what this edge looks like. And its name is the Oort cloud.

The hypothetical structure of the Oort cloud: an inner, disk-shaped cloud surrounded by a spherical outer structure. Image credits Pablo Carlos Budassi via Wikimedia.

Ask anyone on the street where the Solar System ends, and they’re likely to mention Pluto. To a certain extent, it wouldn’t be wrong; Pluto really is one of the farthest planets / dwarf planets from the Sun; as of early 2021, the farthest object in the Solar System is Farfarout . But if we want to be all sciency about it — and we do — the Solar System arguably ends where our star’s gravitational influence becomes too weak to capture and hold objects. In other words, it spans over all the space where the Sun is the dominating tidal force (Smoluchowski, Torbett, 1984). Exactly what constitutes the edge of the Solar System is still up to some debate, however, and some sources — including this post by NASA — consider the space beyond the heliosphere as being ‘interstellar space’.

For the purposes of this post, however, we’ll take the volume where the Sun’s gravity reigns supreme as being the Solar System. The point where that influence ends is far, far away from Earth. So far away, in fact, that we’ve never been able to actually see it, and, realistically speaking, there’s no way humanity will reach there while any of us reading this are still alive. But we do have some theories regarding what goes on out there.

The boundary of the Solar System is marked by a hypothetical structure known as the Oort cloud. We estimate that it is a truly vast expanse filled with varied clusters of ice, from innumerable tiny chunks up to a few billion planetesimals of around 20 kilometers (12 mi) in diameter. There are likely a few rocky or metallic asteroids here, as well, but not many in number. The material in the Oort cloud was likely drawn to its current position through the gravitational influence of the gas giants — Jupiter, Saturn, Neptune, and Uranus — in the early days of the Solar System.

All in all, it is one of the most exciting places humanity has not yet reached.

So what is it?

The thing to keep in mind here is that the Oort cloud is a hypothetical structure. We haven’t yet seen it, nor do we have any direct evidence of it being real. But its existence would fit with other elements and phenomena we see in the Solar System, and it does fit our theoretical understanding of the world around us, as well.

The Oort cloud is a vast body. Since it’s a theoretical structure, there’s quite a bit of uncertainty in our estimates of its size. Still, we believe it stretches from around 0.03 to 0.08 light-years from the Sun, although other estimates put its outer boundary at 0.8 light-years from the Sun. There are also estimates that place it between 1.58 and 3.16 light-years away from the Sun. Needless to say, we don’t have a good handle on exactly where it is, and how large it is.

“It is like a big, thick-walled bubble made of icy pieces of space debris the sizes of mountains and sometimes larger. The Oort Cloud might contain billions, or even trillions, of objects,” NASA explains.

But to give you a rough idea of the distances involved, however, we’ll use Voyager 1, the fastest-going probe we’ve ever sent to space, and the one currently farthest away from Earth. On its current course and acceleration, Voyager 1 would reach the Oort cloud in around 300 years; it would take it some 30,000 years to pass through the cloud (depending on its actual dimensions).

Voyager 1. Image credits NASA via Global Panorama / Flickr.

Still, don’t get too excited. None of the space probes humanity has launched so far will still be operational by the time they reach the Oort cloud; despite being powered by RTGs, a type of nuclear battery, all of these crafts will run out of power far before they reach the Oort clour.

Why do we think it’s a thing?

The concept of the Oort cloud was first suggested in the 1930s by Estonian astronomer Ernst Öpik. The idea was cemented in the 1950s when its existence was independently suggested a second time by Jan Oort, a Dutch astronomer. Because of this dual origin, it is sometimes referred to as the Öpik–Oort cloud.

The existence of this cloud was proposed mainly due to comets — long-period and Halley-type comets, to be precise. Since comets coming close to the Sun lose part of their volatile contents (for example water) under the influence of solar radiation, logic dictates that they must form away from the star. At the same time, gravitational influences would see them either collide with a planet or star or be ejected from the Solar System eventually — meaning that their ‘lifespan’ is limited. Since there are still comets zipping around the Sun, this means that there must be a reservoir of comets to be drawn towards our star.

Put together, both of these point to the existence of a cloud-like formation at the very edge of the Sun‘s gravitational influence populated with comet-like bodies — the Oort cloud.

Short-period comets orbit around the Sun every few hundreds of years; because of this short time, it’s generally accepted that they originate from structures closer to Earth, such as the Kuiper belt (a field of asteroids extending past Neptune). Long-period comets, however, can have orbits lasting thousands of years. The only source that could explain such huge spans of time is the Oort cloud. One exception to these rules is Halley-type comets. Although they are short-period comets, we believe they’re originally from the Oort cloud and that they’ve been pulled ever closer to the center of the Solar System under the gravitational effects of the Sun and inner planets.

What are we doing to study it?

The main impediment to our studying of the Oort cloud is distance. It’s simply too far away for our spaceships or probes to reach in any practical manner. There also haven’t been any direct observations of the Oort cloud.

Despite this, its existence is widely accepted in academic circles. Researchers rely on indirect methods of study to peer into the secrets of the Oort cloud. These revolve heavily around the study of comets and their properties. There is also a lot of effort being poured into developing devices and methods that can be used to spot individual bodies inside the Oort cloud. This is no easy feat, as they’re quite tiny by cosmological standards, and very far away.

Once we do have such tools at our disposal, however, astronomers will finally be able to confirm whether the Oort cloud actually exists. It’s very likely that it does, and it would fit with our current understanding of the Universe. But until we can see it, we won’t be able to tell for sure.

Martian outposts could be made with astronaut’s blood, sweat, and pee — quite literally

Building the future’s space colony will take grit, blood, sweat, and tears — quite literally so, according to new research.

Image credits Tatiana Belova.

Researchers at the University of Manchester plan to build astronauts’ future space lodgings out of the astronauts themselves. More to the point, they plan to use the albumin protein naturally present in their blood, alongside urea, a waste product naturally excreted through urine and sweat. These compounds can be mixed with martian soil — regolith — to create building materials that are comparable to, and even out-perform, concrete.

With the sweat of our brows

“Scientists have been trying to develop viable technologies to produce concrete-like materials on the surface of Mars, but we never stopped to think that the answer might be inside us all along,” says Dr. Aled Roberts from The University of Manchester, a co-author of the paper describing the process.

Size and mass are important limitations for any transportation effort, but none much more so than space transportation. Every cubic inch of volume and every gram of weight in a spaceship are carefully planned and accounted for. Nothing is wasted, and nothing that isn’t essential is included — simply because taking something to space takes a fortune in fuel, design, and logistical costs.

This means that it’s simply not economically viable to take a load of concrete or bricks up to Mars or the Moon, for example. Naturally, this is an issue, as we want to have people living on these (and many other) worlds in the future. In a bid to try and solve this issue, the team at Machester worked to develop a way to make local resources usable by the astronauts as building materials.

Maritan regolith has been investigated for this purpose in the past, especially in conjunction with any local water resources. Together, these can produce a mixture that, while not ideal, is appropriate for lightweight construction duties, enough to give missions their first staging base that’s viable for long-term habitation.

The team realized that one resource will never be missing from crewed missions: the crew. The material they developed, AstroCrete, uses the protein albumin isolated from human blood plasma as a binder for lunar or Martian dust. The finished product can withstand compressive strengths as high as 25 MPa (Megapascals). For comparison’s sake, ordinary concrete can withstand forces between 20-32 MPa depending on its exact composition. Further research showed that incorporating urea, a waste product naturally excreted by our bodies through urine, tears, and sweat, can fortify AstroCrete even more, allowing it to withstand close to 40 MPa.

Although these results are based on simulated lunar and martian dust, not the real thing, they are definitely encouraging. The authors estimate that a crew of six astronauts can produce around 500 kgs of high-strength AstroCrete over a two-year mission. It likely won’t be the main material used for construction, but it has potential as a mortar for sandbags or vitrified (heat-fused) regolith bricks. Used in this way, each crew member could supply enough albumin and urea to expand the habitat enough to support one new member. Lodging could thus be doubled on each successive mission at the same site.

“It is exciting that a major challenge of the space age may have found its solution based on inspirations from medieval technology,” said Dr Roberts, noting that animal blood has been used as a binder for building materials in the past.

“The concept is literally blood-curdling”.

The effect can be explained by the proteins in the blood, including albumin, denaturating — in essence, curdling. This results in a much longer molecule that effectively acts the same way as rebar in reinforced concrete, tying everything together.

The paper “Blood, sweat and tears: extraterrestrial regolith biocomposites with in vivo binders” has been published in the journal Materials Today Bio.

Bezos picks aerospace pioneer Wally Funk to join him on space flight

Female pilot Wally Funk wanted to be an astronaut in the earliest days of spaceflight. But she was denied the job in the 1960s because of her gender. Now, she’ll finally have the opportunity to fulfill her dream of going to space. 

Bezos and Funk. Image credit: Blue Origin.

Amazon founder Jeff Bezos announced on Instagram that Funk will be part of a four-person crew that will be launched into space by Blue Origin during a 10-minute flight later this month. This will make Funk, 82-years-old, the oldest person to ever travel to space, after the late John Glenn set the record at age 77 when boarding the Discovery shuttle. 

“I like to do things that nobody’s ever done. I didn’t think I’d ever get to go up” Funk said in a video. “I can’t tell people that are watching how fabulous I feel to be picked by Blue Origin to go on this trip.”

Funk grew up in the western United States in Taos, New Mexico. She was passionate about aviation from an early age, taking her first flying lessons at age nine. She wasn’t allowed to take mechanics at high school as the subject was still reserved for boys. Still, she obtained her pilot license and graduated from Oklahoma State University’s aviation program. 

Funk was one of the Mercury 13 pilots, a program in 1961 created to train women for NASA’s astronaut program. She graduated third in her class after taking rigorous mental and physical tests. But the program was abruptly canceled when the US government decided women shouldn’t use military facilities needed for space training. Her dreams — along with the dreams of all her colleagues — were shattered.

None of the women from program ever made it into space. But now, Funk will have the opportunity to do so on 20 July. She’ll be part of a four-person crew launched into space on the New Shepard rocket. They will experience a few minutes of weightlessness and marvel at the planet’s curvature before returning to Earth. 

Image credit: Blue Origin

Funk applied to become an astronaut at NASA on four occasions but was rejected every time. One of the reasons given was that she didn’t have an engineering degree and had not completed the flight program on a military fighter jet, which couldn’t be done by women at the time. She was essentially rejected because of her gender.

Nevertheless, Funk has never lost her love of flying. “I’ve been flying forever and I have 19,600 flying hours,” she said, also citing her experience teaching more than 3,000 people to fly. She recalled the disappointment when NASA’s program was shut down. “They told me I had completed the work faster than any of the guys,” she said. 

Bezos will also be a passenger on the flight, along with his brother Mark and the as-yet-unnamed buyer of a seat auctioned off in June. Bezos will be stepping down as chief executive of Amazon on 5 July, dedicating more of his time to his space endeavors. He’s been vying with billionaires Elon Musk and Richard Branson to become the first to travel into space on privately owned rockets. 

Branson is set to fly on July 11th, according to a recent announcement by space tourism company Virgin Galactic – which means he’ll be flying before Bezos. “I’ve always been a dreamer. My mum taught me t never give and reach for the stars. It’s time to turn that dream into a reality abord the next Virgin Galactic spaceflight,” Branson tweeted. 

Alien observers from 1,700 star systems could already be aware that there’s life on Earth

As we continue our search for alien life, alien life may have already spotted us.

Gaia’s all-sky view of our Milky Way Galaxy and neighbouring galaxies, based on measurements of nearly 1.7 billion stars. Image credits: ESA.

Cosmic hide and seek

If we would be playing a game of cosmic hide and seek, our position could be spotted from multiple points of the universe.

According to a new study, 1,715 nearby star systems may have been in a position to see Earth in the past 5,000 years. This means that if any of these systems had a species with advanced enough technology looking towards the Earth, they may have spotted the evolution of civilization on the planet. Out of those star systems, 313 exited the Earth transit zone (or ETZ) — where they would have had a direct view to the Earth — in the past few thousand years.

To make matters even more tantalizing, the study goes on to report that out of these stars, 29 potentially habitable worlds orbiting some of these stars could have both seen Earth and received human-made radio waves — a potential tell-tale sign of our civilization.

To reach this conclusion, researchers used the Gaia database — a catalog of public data produced by the European Space Agency, which has data on more than a billion stars in the Milky Way. Using this database, Lisa Kaltenegger (Associate Professor in Astronomy at Cornell) and Jaqueline Faherty (an astrophysicist at the American Museum of Natural History) explored how different vantage points in our cosmic neighborhood would have had a clear view to us.

They found that 1,715 stars are in the right position to have seen Earth since human civilization developed (some 5,000 years ago). Furthermore, they estimate that 75 stars are close enough (within 100 light-years) for human-made radio waves to have reached them. Depending on how advanced our potential observers’ technology would be, they may have been able to figure out that some species are starting to rule the Earth.

Signs of life

You don’t really need to see a planet to know it’s there. A method for detecting exoplanets is to look at stars and notice when there is any dimming in their brightness. When a planet passes between an observer and its star, it produces a small dimming in the star, and the observer can not only know there’s a planet there but also infer its size. If you think that’s pretty net — it gets even better.

When transiting planets block stellar light, a part of that light is filtered through the atmosphere. Based on how it is filtered, an observer can determine whether it has interacted with chemicals like oxygen or methane, which are essential for life as we know it. Oxygen and methane also react to form carbon dioxide and water, which would have sparked even more interest to an observer. Simply put, an intelligent alien observer located in the right place could have figured out the Earth is habitable.

“The discussion on whether or not we should send out an active signal or try to hide our presence is ongoing,” the study notes. “However, our biosphere has modified our planet’s atmosphere for billions of years, something that we hope to find on other Earth-like planets soon. Thus, observing Earth as a transiting planet could have classified it as a living world since the Great Oxidation Event, for a billion years already.”

The universe is vast, and we’ve only explored a tiny part of it so far. Image credits: NASA.

The researchers also point out that while SETI is looking for a very specific kind of life (one that may want to communicate with us and sends out signals), there may be plenty of other life that is quietly observing — which may be far more abundant in the universe.

So far, we’ve only explored a tiny tiny part of our solar system; we’ve only sent astronauts to the Moon, we’ve only recently started sending rovers to Mars, and anything outside our solar system is currently far out of reach. But remote observations such as this one could help us make better sense of the universe around us and maybe, just maybe, someday get in touch with a different civilization. Whether or not that would be a good thing, however, remains to be seen.

The study was published in the journal Nature.

Two new NASA missions earmarked for ‘lost habitable’ planet Venus

NASA’s new administrator, Bill Nelson, has announced that the agency is going back to Venus. Their goal — to understand how Venus turned from a mild Earth-like planet to a boiling, scorching, acid hellscape.

An enhanced image of Venus, via NASA. Image credits J.Gabás Esteban / Flickr.

Two new robotic missions will be visiting Venus, according to Bill Nelson’s first major address to employees, on Wednesday. Machines will carry them out for us, as Venus is the hottest planet in the solar system. The goal of both will be to better understand the history of the planet, and how Venus came to be what it is today.

Knowing our neighbors

“These two sister missions both aim to understand how Venus became an inferno-like world capable of melting lead at the surface,” Nelson said.

The two missions will be named DaVinci+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging) and Veritas (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy). The first will see a ‘small craft’ plunging through Venus’ atmosphere, taking measurements of its physical and chemical properties, while also analyzing the make-up of its clouds. The second will attempt to map out Venus’ surface in a bid to understand its geologic history.

These will be the first missions to Venus that NASA has attempted in over three decades. The last — mission Magellan — reached the planet in 1990.

Both upcoming missions will help us get a better understanding of Venus, from its atmosphere down to the core, NASA scientist Tom Wagner explained.

“It is astounding how little we know about Venus,” he said. “It will be as if we have rediscovered the planet.”

We don’t yet have an exact launch date for these missions, but they’ll both likely take off sometime between 2028 and 2030. Each will receive around $500 million in funding for development (under NASA’s Discovery program). Sadly, although we are going back to Venus, two other proposed missions — to Jupiter’s moon Io and Neptune’s icy moon Triton — didn’t make the cut.

All eyes are on a Chinese rocket — because it’s falling from space and we don’t know when or where

Just last week, China sent the first module of its new space station to orbit. Today, space agencies around the world are anxiously watching the sky, as the rocket used for the journey is falling back to Earth. But we don’t know where, or when.

A Long March 5 rocket at a launch site in Wenchang Spacecraft Launch Center, 2017.

This will likely be the heaviest object to make an uncontrolled reentry into Earth’s atmosphere in over 20 years, according to experts at the European Space Agency, but we can’t know for sure. The Chinese government has a habit of keeping certain information under wraps, especially when it involves military matters, advanced tech, or the Uyghurs, so we simply don’t know how heavy their Long March 5 rocket (the one that’s making the reentry) actually is.

Either way, specialists and sensors around the world are keeping an eye on the situation as it unfolds, and, hopefully, the craft won’t fall on anyone’s head — or on something important.

The Great Leap Back Down

Whether or not this was initially intended is still unknown — there is some debate raging around the development process of the rocket — but the Long March 5 relies on uncontrolled reentries by design. That, by itself, isn’t unheard-of. Many rockets in the past have employed similar reentry approaches.

What is causing a lot of headaches for the global space community is that the rocket relies on uncontrolled reentries and we know next to nothing about its characteristics. Most importantly, we don’t know its mass, which makes calculating its behavior through the atmosphere impossible. In turn, this means we can’t predict when or where it’s going to finally come down with any degree of accuracy.

Reusable rockets, like the ones being tested by Musk’s SpaceX rely on controlled reentry, giving them the ability to change speed and course while flying back down to the surface.

“[The CZ-5B’s] design is not described in detail in public sources but it is estimated to be cylindrical with dimensions of 5 x 33.2 meters (16.4 x 108.9 feet) and a dry mass of about 18 metric tons (19.8 tons),” the ESA wrote for Deutsche Welle.

Right now, rocket’s core is tumbling through low orbit and is expected to start its descent through the atmosphere in the coming days.

The core is the part of the rocket that actually deployed the space station module to orbit. It was expected to start making a controlled reentry into the atmosphere after disengaging from the rocket proper and finishing its mission, however, that didn’t happen.

Ground radar picked up on the core afterwards, as it was travelling at speeds in excess of 15,840 mph (25,490 km/h). It was designated ‘object 2021-035B’ by the U.S. military, and you can see it being tracked here.

This event was not received well by the international community, especially given that this isn’t the first rocket from a Chinese spacecraft to make an uncontrolled reentry to Earth. The last time this happened, in 2017, the Tiangong-1 space station luckily landed in the Pacific Ocean, and nobody was hurt. But there are no guarantees that the same good luck will help us again. As such, several agencies and experts have called for tighter regulation regarding space traffic, especially on the matter of reentry.

Uranus is leaking radiation, researchers say

Astronomers have detected a new, potentially deadly emanation coming from Uranus: X-rays. While most of these are likely produced by the sun and then reflected by the blue planet, the team is excited about the possibility of a local source of X-rays adding to these emissions.

A composite image with Chandra X-ray data from 2002 in pink over on an optical image from the Keck-I Telescope from 2004.

The seventh planet from the sun has the distinction of being our only neighbor that rotates on its side. But that’s not the only secret this blue, frigid dot in space seems to hide, according to new research. The planet also seems to be radioactive — after a fashion. This discovery currently leaves us with more questions than answers, but it could help us better understand Uranus in the long run.

Deep space rays

Since it’s so far away, we’ve had precious few opportunities to interact with the planet. In fact, the only human spacecraft to ever come near Uranus was Voyager 2, and that happened in 1986. So most of our data regarding the frozen giant comes from telescopes, such as NASA’s Chandra X-ray Observatory and the Hubble Space Telescope.

A new study based on snapshots of Uranus taken by Chandra in 2002 and 2017. These revealed the existence of X-rays in the data from 2002, and a possible burst of the same type of radiation in the second data set. The 2017 dataset was recorded when the planet was approximately at the same orientation relative to Earth as it was in 2002.

The team explains that the source of these X-rays, or at least the chief part of them, is likely the Sun. This wouldn’t be unprecedented: both Jupiter and Saturn are known to behave the same way, scattering light from the Sun (including X-rays) back into the void. Earth’s atmosphere, actually, behaves in a similar way.

But, while the team was expecting to observe X-rays coming off of Uranus due to these precedents, what really surprised them is the possibility that another source of radiation could be present. While still unconfirmed, such a source would have important implications for our understanding of the planet.

One possible source would be the rings of Uranus; we know from our observations of Saturn that planetary ring systems can emit X-rays, produced by collisions between them and charged particles around the planets. Uranus’ auroras are another contender, as we have registered emissions coming from them on other wavelengths. These auroras are also produced by interactions with charged particles, much like the northern lights on Earth. Auroras are also known to emit X-rays both on Earth and other planets.

The piece that’s missing in the aurora picture, however, is that researchers don’t understand what causes them on Uranus.

Its unique magnetic field and rapid rotation could create unusually complex auroras, the team explains, which further muddies our ability to interpret the current findings; there are too many unknown variables in this equation. Hopefully, however, the current findings will help point us towards the answers we need.

The paper “A Low Signal Detection of X‐Rays From Uranus” has been published in the Journal of Geophysical Research: Space Physics.

A new approach to cleaning space junk is being tested in space right now

A rocket blasted off last Saturday from the Baikonur Cosmodrome in Kazakhstan, and it could lead to a much cleaner orbit around our planet.

One of the satellites involved in the mission. Image credits ESA.

Known as the End-of-Life Services by Astroscale or ELSA-d, the mission aims to test a theoretical approach to cleaning out space junk. The craft will look for dead satellites around our planet, attach to them, and slowly push them towards our planet so they burn up in our atmosphere. According to Astroscale, the Japan-based company behind this mission, there are over 8,000 tons of debris in the Earth’s orbit, which represents a very real threat for services such as weather forecasting, telecommunications, and GPS systems.

Decommission mission

The mission will be trying out a new approach that involves using magnetic docking to capture space junk. While no actual junk will be captured just yet, two satellites — a ‘servicer’ and a ‘client’ satellite — were launched into orbit to test the approach. As part of ELSA-d, the servicer will release and then try to re-capture the client, which, essentially, serves as a mock piece of space junk.

This catch and release process will be repeated over the next six months. The UK-based ground team will use data from this step to improve the satellite’s ability to lock onto and dock with its targets.

One important thing to note is that the satellite isn’t meant to remove the clutter that is already in orbit. Rather, the team is after future satellites that, they say, will be equipped with special docking clamps before launch.

Space debris are a growing problem, one which can impact our lives in quite unpleasant ways. Taken to the extreme, such cluttering could even prevent us from ever leaving the Earth again — but we’re not there yet. For now, they just risk impacting and downing our satellites, meaning services that rely on orbital networks, such as GPS and mobile phones, are also at risk. They’re also a hazard to astronauts and other missions.

According to NASA, there are at least 26,000 pieces of space junk in orbit about the size of a softball. Going on along at roughly 17,500 mph, each could “destroy a satellite on impact”. Apart from that, another 500,000 pieces of debris represent “mission-ending threats”, the report adds. The rest, estimated at more than 100 million pieces, are around the same size as a grain of sand. That’s not to say they’re harmless, however — each could pierce a spacesuit

Clearing the Earth’s orbit would go a long way towards keeping us safe and happy, both on the surface and in space. Taking down what’s already there is, obviously, a very sensible approach; but so is limiting how much junk we’ll be putting there in the future. Missions such as ELSA-d showcase how we can prepare for a more sustainable use of outer space, an element that will only grow in importance as humanity makes bolder steps towards the stars.

Researchers find four strains of bacteria on the ISS — three are completely new to science

Life finds a way, the old saying goes. According to a new paper, that includes ‘living on a spaceship’.

Transmission electron micrograph of strain S2R03-9T Methylobacterium jeotgali, a relative of the new strains. Image via Wikimedia.

A team of researchers from India and the US working in collaboration with NASA report discovering four bacterial strains living on the International Space Station (ISS). Three of these were completely unknown to science until now. Three of these strains were isolated in 2015 and 2016 — one in an overhead panel in a research lab, the second in the station’s Cupola, and the third on the surface of the crew’s dining table. The fourth strain was isolated from an old HEPA filter that was brought back to Earth in 2011.

All of these strains belong to a ‘good’ family of bacteria found in soil and freshwater here on Earth. They’re involved in nitrogen fixation processes, plant growth, and in fighting plant pathogens.

Out of this world

These bacteria likely made their way onto the ISS when the crew first started growing a small number of plants aboard to supplement their diets. Plants don’t develop and live on their own, but generally rely on bacterial communities for several essential services; as such, finding plant-related microbes in their environment (the space station) isn’t very surprising.

However, only one of these was previously identified by researchers: the one from the used HEPA filter. This strain was identified as belonging to the species Methylorubrum rhodesianum. The other three were genetically sequenced and found to all belong to the same, new species. They were temporarily christened IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5.

The team, led by University of Southern California geneticist Swati Bijlani, proposes the name Methylobacterium ajmalii for the species, after Indian biodiversity scientist Ajmal Khan. The new species is closely related to the already-known M. indicum bacteria. The genetic sequencing of these bacteria was meant to help us better determine how they relate to other bacteria, but also to help us determine the genetic elements that make them suited to life in the unusual conditions aboard the ISS.

“To grow plants in extreme places where resources are minimal, isolation of novel microbes that help to promote plant growth under stressful conditions is essential,” Kasthuri Venkateswaran and Nitin Kumar Singh from NASA’s JPL, two members of the team, explained in a press statement.

“The whole-genome sequence assembly of these three ISS strains reported here will enable the comparative genomic characterization of ISS isolates with Earth counterparts in future studies,” the team explains in their study. “This will further aid in the identification of genetic determinants that might potentially be responsible for promoting plant growth under microgravity conditions and contribute to the development of self-sustainable plant crops for long-term space missions in future.”

At least one of the strains, IF7SW-B2T, shows promise in our search for genes involved in plant growth, they add. Still, we’re only just beginning to understand the wealth of bacteria living aboard the ISS. Collecting samples isn’t hard, but taking them to Earth for proper examination is. The crew has taken over 1,000 samples so far, but they’re all still awaiting transport back to Earth.

The paper “Methylobacterium ajmalii sp. nov., Isolated From the International Space Station” has been published in Frontiers in Microbiology.

SpaceX rocket aced a landing, then exploded so hard it launched again for a bit

Luckily, nobody was injured and the company seems to be taking the events in good spirits.

Image credits Official SpaceX Photos / Flickr.

SpaceX is a company that’s definitely not afraid to take risks and try new things. And a natural part of such an approach is that things will often not go according to plan, and sometimes they fail spectacularly. Yesterday was one such day, after one of the company’s Starship rockets touched down in Texas.

Post-landing problems

SpaceX wants to make going to space cheap enough that it’s practical. A large part of that plan involves cutting down costs by making rockets reusable. They’re hard at work doing that.

So far, they’ve run into their fair share of trouble. Their approach involves using the rocket’s thrusters in flight to orient the craft upright before landing. Two of their previous test flights ended in fireballs though, because, while the rockets maneuvered as intended, they didn’t decelerate fast enough before touching down.

The test yesterday went much better than those two. It used a full-scale prototype of the rocket, which launched, traveled around 6 miles (10 kilometers), and then headed in for a landing. The maneuvers worked like a charm, and the craft flipped upright after descending close enough to the pad. “Third time’s the charm as the saying goes,” quipped SpaceX commentator John Insprucker, referring to the previous trials, as the rocket touched down successfully.

A few minutes later, however, the rocket would explode, briefly sending itself upon a new flight path.

SpaceX has not issued an official statement on the event yet, but CEO Elon Musk did comment on his personal Twitter account with good humor.

Technically speaking, it did. The first time.

It’s all good to make fun of a bad situation, but even considering that the rocket exploded after landing, this is quite the feat. SpaceX’s approach was under question given how the last two tests panned out, but yesterday’s shows that the plan was sound after all. Most importantly, nobody was injured, and rockets can be rebuilt. Even a result like this — which was arguably, ultimately, a failure — brings us one step closer to the days when rockets are reusable and don’t explode on the landing pad. Both extremely desirable traits, as the Spaceship is earmarked to ferry people to and from Mars for SpaceX.

“SpaceX team is doing great work! One day, the true measure of success will be that Starship flights are commonplace,” Musk added in a later tweet. It is not yet clear why the rocket exploded, but according to the Independent, “observers speculated that it was the result of a rough landing combined with a methane leak”.

Astronomers found a giant cluster of galaxies from the early universe

Let’s start with the history of the universe (a very brief one). After the Big Bang, the Universe was essentially a hot soup of particles. Things started to cool down and eventually started forming hydrogen atoms. At some point, the universe became neutral and transparent, but because the clouds of hydrogen collapsed very slowly, there were no sources of light — it was a period of complete and utter universal darkness aptly called Dark Ages.

The famous dark matter slowly started to form structures that later became the first source of light in the universe. The emergence of these sources occurred in the Epoch of Reionization (EoR), around 500 million years after the Big Bang. Now, astronomers have found that formed not that long after this period.

The Cerro Tololo Inter-American Observatory (CTIO) in Santiago, Chile. Credits: Dark Energy Survey.

Astronomers from China, the US, and Chile have now found a huge galaxy protocluster (a dense system of dozens of galaxies from the early universe that grows together) from the early days of the universe. Called the LAGER-z7OD1 cluster, it dates from a time when the universe was still a baby — only 770 million years old, early in its history. These objects are important tools that enable astronomers to examine the EoR.

The group that worked detecting these objects is called the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER). Lyman Alpha Galaxies are very distant objects that emit radiation from neutral hydrogen and they are the components to find clusters that are so old.

LAGER primarily used the Dark Energy Camera (DECam) from the Cerro Tololo Inter-American Observatory (CTIO) 4-m Blanco telescope in Andes, Chile. They found out was it is a system with a redshift of 6.9 — here’s why that’s intriguing.

Redshift is a measure of how something is moving in space: if it moves away from us we see a longer wavelength, which means a positive redshift and a wavelength skewed towards red — if it is moving towards us, it means shorter wavelengths, a negative redshift, and a wavelength skewed towards blue. The bigger the redshift, the more distant it is from us.

The cluster has 21 galaxies and if you want to estimate distance, the volume is probably 51,480 Mpc³ (1 Mpc is almost 3 million light-years) and it’s about 3,700,000 billion times more massive than the Sun. In addition, it has an elongated shape which means subclusters merged to form the bigger structure.

It’s basically a gazillion miles from us, but a gazillion isn’t good enough for astronomers — they always want to know just how far away things are. In this case, however, an approximation will have to do.

The problem is that we don’t have the exact distance of things because we don’t know exactly the universe’s speed of expansion. The farthest object the Hubble Space Telescope Collaboration detected is a galaxy called GN-z11, with redshift 11.09. A recent discovery of the furthest quasar with the help of another Chile-based observatory, the Atacama Large Millimeter/submillimeter Array (ALMA), also found a redshift of 7.642.

The furthest galaxy ever detected, GN-z11. Credits: NASA-Hubble Space Telescope, ESA, P. Oesch (Yale University), G. Brammer (STScI), P. van Dokkum (Yale University), and G. Illingworth (University of California, Santa Cruz).

The Plack Collaboration estimated that the EoR probably started at z=7.67. This estimation uses the polarization of the Comic Microwave Background photons, just like polarizing light with sunglasses, but with a level of sensitivity so high that the instruments to detect it must be at temperatures close to absolute zero. Another important conclusion came from search for quasars formed in this period, usually the many papers about it conclude that the end of the EoR was around z=6.

Lyman Alpha Galaxies and quasars are major findings to understand the EoR. The best sample of quasars we have now has only 50 quasars, not much to represent the EoR for the entire universe. LAGER-z7OD1 is an example of cluster which possibly formed in the middle of the process, until absolute certainty is obtained more observations like this one need to come.

The study was published in Nature Astronomy.

Titan’s largest methane sea is over 1000 feet deep, says a new paper

Titan’s seas should be deep enough for a robotic submarine to wade through, a new paper explains. This should help pave the way towards our exploration of Titan’s depths.

Radar map of the polar region of Saturn’s moon Titan. Image credits NASA / JPL-Caltech.

Fancy a dip? Who doesn’t. But if you ever find yourself on Titan, Saturn’s biggest moon, you should stay away from swimming areas. A new paper reports that the Kraken Mare, the largest body of liquid methane on the moon’s surface is at least 1,000 feet deep near its center, making it both very deep and very cold.

While that may not be very welcoming to humans, such findings help increase our confidence in plans of exploring the moon’s oceans using autonomous submarines. It was previously unknown if Titan’s methane seas were deep enough to allow such a craft to move through.

Faraway seas

“The depth and composition of each of Titan’s seas had already been measured, except for Titan’s largest sea, Kraken Mare—which not only has a great name, but also contains about 80% of the moon’s surface liquids,” said lead author Valerio Poggiali, a research associate at the Cornell Center for Astrophysics and Planetary Science (CCAPS).

Titan is a frozen moon that shines with a golden haze as sunlight glints on its nitrogen-rich atmosphere. Beyond that, however, it looks surprisingly Earth-like with liquid rivers, lakes, and seas sprawling along its surface. But these are not made of water — they’re filled with ultra-cold liquid methane.

The findings are based on data from one of the last Titan flybys made during the Cassini mission (on Aug. 21, 2014). During this flyby, the probe’s radar was aimed at Ligeia Mare, a smaller sea towards the moon’s northern pole. Its goal was to understand the mysterious “Magic Island” that keeps disappearing and then popping back up again.

Its radar altimeter measured the liquid depth at Kraken Mare and Moray Sinus (an estuary on the sea’s northern shore). The authors of the paper, made up of members from both NASA’s Jet Propulsion Laboratory and Cornell University, used this data to map the bathymetry (depth) of the sea. They did this by tracking the return time on the radar’s signal for the liquid’s surface and the sea bottom while taking into account the methane’s effect on the signal (it absorbs some of the energy from the radio wave as it passes through, in essence dampening it to an extent).

Colorized mosaic of Titan’s Kraken Mare. Liquids are blue and black, land areas appear yellow to white. The surface was mapped using radar data from NASA’s Cassini. Image credits NASA / JPL-Caltech / Agenzia Spaziale Italiana / USGS via Wikimedia.

According to them, the Moray Sinus is about 280 feet deep, and the Kraken Mare gets progressively deeper towards its center. Here, the sea is too deep for the radar signal to pierce through, so we don’t know its maximum depth. The data also allowed us some insight into the chemical composition of the sea: a mix of ethane and methane, dominated by the latter. This is similar to the chemical composition of Ligeia Mare, Titan’s second-largest sea, the team explains. It might seem inconsequential, but it’s actually a very important piece of information: it suggests that Titan has an Earth-like hydrologic system.

Kraken Mare (‘mare’ is Latin for ‘sea’) is our prime choice for a Titan-scouting submarine due to its size — it is around as large as all five of America’s Great Lakes put together. We also have no idea why this sea doesn’t just evaporate. Sunlight is about 100 times less intense on Titan than Earth, but it’s still enough to make the methane evaporate. According to our calculations, this process should have completely depleted the seas in around 10 million years, but evidently, that didn’t happen. This is yet another mystery our space-faring submarine will try to answer.

“Thanks to our measurements,” he said, “scientists can now infer the density of the liquid with higher precision, and consequently better calibrate the sonar aboard the vessel and understand the sea’s directional flows.”

The paper “The Bathymetry of Moray Sinus at Titan’s Kraken Mare” has been published in the journal Journal of Geophysical Research: Planets.

Six asteroids to pass close to Earth tomorrow, says NASA

The 2020 US Presidential election was really a wild ride, huh? Well, strap in because it’s not over yet.

Artist’s impression of the double asteroid Antiope. Image credits ESO via Wikipedia.

NASA’s Center for Near Earth Object Studies reported that six pieces of space rock will be passing by our planet tomorrow, 20th Jan., when the US celebrates Inauguration Day — the day when the new president-elect is vested with the powers of his office.

The agency says everything should be alright and that these meteorites will zip past harmlessly. Still, after 2020 and this election’s history, we can all be forgiven some wallowing in skepticism and despair at the thought that they might not. We’ve earned it.

Friends in high places

Inauguration Day marks the transition of power from one administration to the next — this year, that means from the Trump administration to the Biden team. It also marks the occasion on which four meteorites will do a close fly-by of Earth, hopefully missing us entirely.

According to NASA’s estimates, the closest one (asteroid 2021 BK1) will fly by Earth at around the same distance the Moon orbits at. So they should be pretty harmless. The largest of them is around 93 meters in width, which is the height of the Statue of Liberty.

All in all, we should be fine and well-missed by the space rocks. Still, this is close enough to be considered a “close approach” by NASA, and the agency will keep a close eye on the asteroids and their trekking. So let’s all hope for an uneventful Inauguration Day.

More information on these asteroids here (all six asteroids listed for 2021-Jan-20 in the table).

The largest planetary ring system we’ve found would dominate the sky — if it was in our solar system

When talking about planetary ring systems, Saturn and Jupiter likely spring to mind — they are our closest ringed neighbors, after all. But although impressive, their rings aren’t that large, in the grand scheme of things. Jupiter’s aren’t that large even when judging only by our Solar System. Neptune and Uranus also have rings, but they’re tinier.

A picture of Saturn’s ring structure created using data from the Cassini craft on April 19 2017. Image credits Kevin Gill / Flickr.

Luckily, the Universe is a huge place, and there’s no shortage of beautiful ring systems to enjoy. There are also plenty of grand, sprawling ones to take your breath away. So, today, let’s take a look at what these ring systems actually are, how they form, and the biggest ones we’re spotted so far.

What even are planetary ring systems?

Every stellar body generates a gravitational field. Large, dense ones create a strong pull; giant, ponderous planets generate an immensely strong pull. It’s these large planets, typically gas giants, which sport planetary ring systems. It’s not all that different from how our Earth sports a Moon.

Ring systems are sprawling fields of material such as rocks, minerals, and ice. They look like wispy sheets of material, but up close, these are massive structures. They’re not particularly thick (Saturn’s rings, for example, are probably only 50 meters high) but they go all the way around a planet, most often in several different ‘rings’ each at different distances from the planet.

The exact size of the particles in a ring system is dependent on several factors: the material these particles are made of (mainly its specific strength and density), how far it is from the planet, and the strength of tidal forces at that altitude. In other words, rings are made up of particles in all kinds of shapes and sizes; the planet’s gravitational pull and rotation will try to grind them down, while a material’s toughness and its distance from the planet will help it survive in larger chunks. The materials they’re made of aren’t consistent — it’s all related to how the system and planet formed, and their history since. It’s generally gas, dust, and ice, but according to NASA, such particles can be “as large as mountains”.

Lastly, know that although we call them ‘planetary’ ring systems, they don’t only form around planets. Minor planets, moons, unignited stars (brown dwarfs) can also sport ring systems. There is even some evidence of a similar structure residing in the void between Venus and Mercury.

How do they form?

As far as we understand, there are three main ways for a planet to get the material that makes up its rings.

The first one is that they simply ‘gathered’ it in the early days of the system they inhabit — the so-called accretion stage. In this phase, a star system resembles a disk churning around its star. In time, pockets of matter come together (accrete), gaining gravitational strength, which keeps drawing more material in. This is how stars and planets form (the star just forms first and can thus grab most of the matter in the disk).

If a planet forms early and gets large enough, it can start drawing in material from around it, preventing it from accreting into the forming planets. Instead, it forms a ring system under the hosts’ tidal forces (gravitational pull + rotational movement). This is exactly the same process that builds planets around a star from the primordial dust, only at a much smaller scale.

Detail of Saturn’s shepherd moons, created using data from Cassini. Image credits NASA-JPL / Caltech.

The second way is to use your gravity to capture asteroids or moons or let some form near you and pull them inside your Roche limit. This is a theoretical boundary beyond which a planet’s tidal forces will break apart any other stellar body. Inside this range, moons and asteroids will be ground into dust. The Roche limit also dictates how far a body’s influence extends during the accretion phase — nothing can form within this boundary due to the extreme tidal forces present.

The third way generally doesn’t form very large ring systems by itself. It involves a planet capturing any material produced by asteroids crashing into its moons, or materials produced by volcanic processes that make it into space (from traditional or cryovolcanoes). Compared to the previous two, such capture processes involve minute amounts of matter.

One of the final elements that can help produce and maintain a planetary ring system is shepherd (or ‘watcher’) moons. These are larger bodies that orbit through or on the edges of rings. Their gravity pulls at particles in the ring as they orbit, which helps to maintain the shape of the rings — they ‘herd’ the ring particles, hence their names. If you see any empty strips in a ring system, it’s very likely that a shepherd moon created it.

The movements of such a moon through the ring are truly a thing of beauty. As they orbit, shepherd moons form ripples through the ring, like the wake of a boat traveling over a calm lake. This only makes the thought that such moons tend to be short-lived that much sadder. They’re generally inside their host’s Roche limit, so they will eventually be broken apart and ground down.

Now that we have a better understanding of what they are and how they form, let’s take a look at the biggest, most impressive ring system we’ve found so far.


Artistic rendering of the exoplanet and its impressive rings. Image via Wikimedia.

Discovered way back in 2015, J1407b boasts the largest ring system we’re ever seen — around 200 times larger than Jupiter’s (the largest in our solar system). The planet that hosts it is equally immense: we don’t exactly know whether it’s a gas giant or a brown dwarf. So far, it’s been referred to as a super-Jupiter type of stellar body.

To give you an idea of just how stupidly massive this ring system is, if Saturn had the same rings, they would be many times larger in diameter than the moon in the night’s sky. It’s not only that you could see it easily with the naked eye — it would pretty much dominate the view. All in all, the exoplanet boasts some 30-odd layers of rings.

“It’d be huge. You’d see the rings and the gaps in the rings quite easily from Earth,” said Matthew Kenworthy of the Leiden Observatory in the Netherlands, one of the co-authors on the paper describing the findings, at the time. “It’d be several times the size of the full moon.”

Maybe the size of its rings helped too because J1407b was the first confirmed case of an exoplanet with a ring system. So far, it’s also the only exoplanet with rings that we’ve spotted.

Still, in cosmological terms, such lush manes of rings do not last for long. Researchers expect them to get progressively thinner and disappear in the next several million years as new moons form from the sheer quantity of material zipping and zapping through J1407b’s rings. Compared to planets in our solar system, J1407b is also very young, at only about 16 million years old. The Sun and Earth are 4.5 billion years old.

So it might be just youthful energy that makes large ring systems possible. Right now, we simply don’t know. The methods we use to spot exoplanets (planets outside our solar system) aren’t very good at all at picking up ring systems — they can do it, but there’s a lot of luck involved.

For now, our best knowledge of planetary ring systems come from our neighboring planets. There may well be larger rings than those boasted by J1407b out there, but until we can get a better view into deep space — or, even better, make our way there — they will likely remain undiscovered.

Milky Way’s X-ray reveals giant bubbles

The Spectr-RG spacecraft carrying the eROSITA (a Max Planck Institute instrument) telescope was launched by the Russian Roscosmos in 2019, focusing observations on the X-ray part of the electromagnetic spectrum. The mission’s objectives are to observe galaxy clusters and study the growth of large scale structure, to detect supermassive black holes, observe supernova remnants and X-ray binaries.

It’s now starting to deliver results.

eROSITA’s observations of prominent X-ray sources. Credits: eROSITA Collaboration.

We’re made of starstuff

In the last six months, the mission collected data of the whole sky within energies from 0.2 to 8 KeV (200-8000 eV). An electron-volt(eV) is an energy unit equivalent to the amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum. It’s not a lot: if you go to the hospital and get your arm X-rayed, the energy of the medical X-ray photons is around 200,000 eV (0.2 MeV), any lower and you wouldn’t see your bones on the X-ray. This is because the calcium in our bones absorb those photons with this amount of energy and become visible for the doctor.

Using a somewhat similar approach, eROSITA’s all-sky sky map images a variety of objects, in different energy ranges. In the 0.3 to 2.3 KeV map is possible to see prominent X-ray sources in the sky, like Large Magellanic Cloud in the southern part of the galactic map. Towards the center, one can see the Vela Supernova Remnant, the result of a supernova explosion that occurred approximately 11,000 years ago. Maybe the brightest source in the map is the Scorpius X-1(Sco X-1), which is a X-ray binary.

But perhaps most intriguingly, the map also shows a huge bubble, present both in the southern and northern part of the galaxy. It’s a huge bubble, which seems to be a result of an event emerging from the galactic center — something that happened 20 million years ago. The structure is so extensive it has comparable size to the galaxy. Its boundary is hotter than the outside due the great energy release from the galactic center.

eROSITA latest discovery, the eROSITA bubbles(pink). Credits: eROSITA Collaboration.

Previous observations from the Fermi telescope have shown a similar structure but in the gamma-ray band. The Fermi bubbles are smaller but with same structure of the newest discovery. The comparison between the bubbles is in the image bellow.

eROSITA bubbles(yellow), Fermi bubbles(purple) and the Milky Way’s disk(blue) size comparison. Credits: eROSITA Collaboration.

The discovery suggests that they are a result of the same event, but the cause of the connection is still unknown. They appear to be structures left by accreting supermassive black holes, like seen in the Centaurus A galaxy or supernovae remnants, though nothing is conclusive yet.

eROSITA(blue), Fermi(red) bubbles. Credits: eROSITA Collaboration.

The bubble’s discovery provides more insight about galaxy formation and its structure, this means more knowledge about the past of our galaxy. The second complete scan made by eROSITA is close to an end, now with twice the number of photons from the first scan.

The study was published in the journal Nature.

No one knows for sure the expansion rate of the universe

In the late 1920s, Edwin Hubble spent a great deal of his time investigating what was then called Nebulae, interstellar structures that we now know as galaxies. He used to work with the top instrument of the time, the 2.5 m Hooker telescope at Mount Wilson, collecting data from those distant objects and comparing them.

The galaxies observed by Hubble were different from one another. Some were redder, indicating they are farther away from us. This happens because the speed of light is a fixed value, and the most distant objects take longer to send their light to our eyes than the closest ones. The color red has a longer wavelength, meaning this color can travels great distances. So bluer galaxies, with blue being on the shorter end of the wavelength spectrum, are likely closer.

Interestingly, Hubble realized that the redder objects were also the ones traveling away from us faster than the blue galaxies. In other words, if a galaxy is very distant, it’s moving away from us faster than a closer galaxy. So the universe was pretty clearly expanding.

Hubble’s observations concluded that the universe expands with a velocity of 500 km/s for each 308 trillion and 570 million km — which is defined as one Megaparsec. In other words, Hubble concluded that the universe is expanding at a speed of 500 km/s/Mpc. But that’s not the end of this story. In fact, it’s only the beginning.

The 2018 Planck map of the temeprature anisotropies of the CMB. Credits: Planck Collaboration.

Today’s values, calculated with more precise instruments, are around 70 km/s/Mpc and this expansion rate is called Hubble Constant (H0). The problem if you measure this expansion rate in different ways, you’ll end up with different values — something called the ‘H0 tension’.

Important information about the Hubble constant comes from something called Cosmic Microwave Background. The Cosmic Microwave Background (CMB), as calculated by the European Space Agency’s Planck Collaboration, is the light emitted 380,000 years after the Big Bang. Measurements from the CMB by the latest Planck data have a ‘H0’ value of 67.4 km/s/Mpc. But a local measurement using the brightness of supernovae type Ia has bigger values of 72 km/s/Mpc.

In order to get 74, the SH0ES Collaboration uses a galaxy (NGC 4258) as the reference to calibrate Cepheids and SN-Ia and obtain the H0 value. SN-Ia and Cepheids are so-called ‘standard candles’ — objects with a fixed, known brightness pattern. By having a catalog of objects with standard brightness, scientists can infer the distance of the candles.

Planck, on the other hand, uses a technique not based on direct observation. In this case, the CMB can measure the sound horizon, which is a standard ruler. It needs to use the standard model of cosmology to obtain the expansion rate.

Other observations that have similar methods to the two above also vary in correspondence. The most anticipated procedure uses Gravitational Waves. It is similar to the standard candles, except this time the objects have the ‘sound’ as a pattern. Unfortunately, there are very few observations of this sort since it is a recent method of observation. One observation by LIGO that resulted in a rich catalog was GW170817, the merging of two neutron stars. The importance of this event is due to the electromagnetic observation that came together. The collision was so violent it resulted in a gamma-ray outburst, detected approximately 2s after the merging. GW170817’s H0 is equal to 69 km/s/Mpc.

Artistic impression of GW170817. Credits: NSF/LIGO/Sonoma State University/A. Simonnet

The matter is hotly debated by researchers. Since the last post covering universal expansion was published on ZME Science, approximately 24,000 papers discussing the issue have been published. Many are analyzing and comparing different measurements of the value and many reviews are trying to make sense of separate studies. Despite the extensive investigation though, no conclusions were drawn.

More recently, a collaboration of the Atacama Cosmology Telescope (ACT) in Chile used the same method Planck used. Different from the ESA telescope, ACT is ground-based and covers a smaller area of the sky. Yet it agrees with Planck, the close value of 67.9 km/s/Mpc. This suggests that the same type of procedure results in similar values.

Temperature fluctuations in the observed sky by ACT. From -250 micro Kelvin to +250 micro Kelvin. Credits: ACT Collaboration.

But how can that be if the universe is supposed to have the same behavior independent from the way we observe it? The answered could be errors with the observations, but it could also be that our current model of the universe is not correct. With the ATC it appears that the cosmological model can’t describe well the CMB, and we’re not really sure why.

From now on the focus will turn towards Cepheids and SN, but yet no one is sure what exactly is the problem: new physics needs to be developed or more and more observations will answer questions? Until there more papers will fill the Google Scholar pages.

The Betelgeuse false alarm and Red Giants dust hypothesis

Illustration of dust ejection from Betelgeuse. First two panels show the beginning of the outburst, last two panels simulate two points of view of the cooled mass. Credits: NASA, ESA, and E. Wheatley (STScI)

Betelgeuse is a red giant star with a radius of 617,100,000 km — a whopping 887 times the Sun’s radius. To have an idea of the size, Orion’s star is so big it could envelop Jupiter’s entire orbit (depicted in the image below).

Betelgeuse size comparison. Credits: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervell.

In December 2019, astronomers noticed a sudden drop in the star’s brightness. The observations continued until it reached a minimum in February 2020. The first hypothesis that came to everyone’s mind was that the star was in its final days and would explode to a Type II Supernova, which seemed plausible due to its size and characteristics.

Betelgeuse is a massive and very hot star, so it burns its fuel faster than smaller stars. As a result, red giants like Betelgeuse have shorter lives (Betelgeuse is only 10 million years old while our Sun is 450 times older) and it is estimated that it has about 100,000 years left.

When a star this size explodes into a supernova, its brightness reaches a maximum and then stabilizes as it decreases in brightness. If Betelgeuse were to indeed turn into a supernova, we’d see this in the night sky as something having 10% of the Moon’s brightness — but at its peak, the brightness will even outshine the moon in the first days of high luminosity.

However, scientists have suggested that dust in front of our point of view made it appear less bright. The Hubble space telescope observations of the sudden dimming suggested that mass ejection from the star created a bubble of gas that quickly cooled down and the dust became what we can imagine as a shadow in our line of sight, which made it appear less luminous.

After the (metaphorical) dust had settled, Betelgeuse still did not turn into a supernova. So what did it actually do?

What is the dust all about?

Another group decided to check using a submillimeter telescope. Submillimeter astronomy observes a specific part of the electromagnetic spectrum: between far-infrared and microwave wavelengths.

These parts of the spectrum help researchers detect the presence of water vapor, as well as molecular oxygen and other molecules. Observations with submillimeter telescopes are ideal for detecting the ingredients which form stars and planets.

Evolution of stars. Betelgeuse fits the third line evolution. Credits: NASA/CXC/M.Weiss.

Whenever a submillimeter telescope points to nebular dust, the image is very bright due to the dust itself. The James Clerk Maxwell Telescope didn’t have a significant signal from the ‘dust’ ejected by Betelgeuse, which essentially invalidated the dust hypothesis. So it wasn’t a supernova event and there wasn’t any dust — so what could have caused Betelgeuse’s loss of luminosity?

Another giant goes dark

A more recent study looked at another giant star, finding that this type of mass ejection event may be common for massive stars than we thought, and the missing piece is a gas bubble around the star. These gas bubbles which are ejected may be good candidates to understand more about the building blocks of the formation of future stars.

VY Canis Majoris (VY CMa) is a hypergiant located in the Canis Major constellation, almost twice as large as Betelgeuse. Data collected with the Hubble telescope showed that a similar variability of brightness from Betelgeuse — in other words, what happened with VY CMa likely also happened to Betelgeuse.

This research compared the recent dimming of the VY CMa with historical data from the 1880-1890 and 1920-1940 periods. The Canis Major’s star has a longer period of alternating from maximum to minimum brightness. This could be related to the size of the object: a larger star requires a longer period of dust ejection, consequently, more dust escapes it.

It was a disappointment for many astronomers who were hoping to see something spectacular — but instead, more questions than answers seem to have emerged about the behavior of these supernovae. From now on, we wait for further research and observation to better understand red giants mass ejections.

This could be the first extragalactic planet we’ve ever found

We’ve found a lot of planets in recent years. Big and small, far and close, but they all have one thing in common: they’re in our galaxy. Now, a team of researchers from the US and China believe they’ve found the first planet outside of our galaxy, and it’s glorious.

Left: false RGB Chandra/ACIS-S image of the Whirlpool Galaxy, M 51 (total exposure of ≈850 ks). The planet M 51-ULS1 is the orange source at the center of the 60” × 60” dashed white box. Right: HST image of the area defined by the white box in the top image. Image Credits: arXiv:2009.08987 [astro-ph.HE]

Galaxies are big. Our galaxy is thought to host more than 100 billion stars, and measure about 100,000 light-years across. In other words, it would take a beam of light 100,000 years to cross the galaxy, and the fastest shuttle we’ve ever built only hit a peak speed of about 3% the speed of light.

But even this is just peanuts to space. Our neighboring Andromeda galaxy, for example, is over two times bigger than the Milky Way, and the biggest galaxy we know of (IC 1101) is 50 times the Milky Way’s size and about 2,000 times more massive.

The new planet candidate lies a whopping 23 million light years away, in the M51 Whirlpool Galaxy, relatively close to Ursa Major. Normally, it wouldn’t really be possible to identify a planet this far away, but researchers took advantage of a rare set of circumstances.

The Whirlpool Galaxy (M51, NGC 5194), a classic spiral galaxy, and its companion NGC 5195. Image credits: NASA / ESA.

The object lies in a binary system that has a either black hole or a massive neutron star at the center (we don’t know for sure, but it’s very massive). This object is sucking on a nearby star, and in the process, emitting a huge X-ray signal which caught the attention of astronomers. X-ray signals of this nature are rare on the night sky, so it made for an interesting observation. The X-ray signal also happens to be very small — so small that even a relatively small object passing in front of it would temporarily block it, and this is exactly what researchers have observed.

“It is the first candidate for a planet in an external galaxy,” researchers note in the study. If it is confirmed, the planet would be called M 51-ULS1.

Simply put, there seems to be a planet passing in between this X-ray source and the Earth, creating an eclipse-type phenomenon. Researchers aren’t exactly sure that it is a planet since it’s too far to observe it directly, but they’ve ruled out all likely possibilities.

It will be a while before we can confirm this finding, but for now, it’s safe to say that out of the thousands of planet candidates we’ve found, we also have one outside our galaxy — and that’s pretty awesome in itself.

Journal Reference: M51-ULS-1b: The First Candidate for a Planet in an External Galaxy, arXiv:2009.08987 [astro-ph.HE] arxiv.org/abs/2009.08987