Long After Humanity is Gone and the Sun Dies, the Water Bears Will be There

Long After Humanity is Gone and the Sun Dies, the Water Bears Will be There:

Like all living creatures, stars have a natural lifespan. After going through their main sequence phase, they eventually exhaust their nuclear fuel and begin the slow process towards death. In our Sun’s case, this will consist of it growing in size and entering the Red Giant phase of its evolution. When that happens, roughly 5.4 billion years from now, the Sun will encompass the orbit’s of Mercury, Venus, and maybe even Earth.

However, even before this happens, astronomers theorize that the Sun will dramatically heat up, which will render Earth uninhabitable to most species. But according to a new study by a team of researchers from Oxford and the University of Harvard, the species known as tardigrades (aka. the “water bear”) will likely survive even after humanity and all other species have perished.

This study, which was recently published in the journal Scientific Reports under the title “The Resilience of Life to Astrophysical Events“, was conducted by Dr. David Sloan, Dr. Rafael Alves Batista – from the Department of Astrophysics at Oxford University – and Dr. Abraham Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA). As they indicate, previous studies into the effect Solar evolution will have on life have been rather lopsided.

Artist’s impression of the Earth scorched by our Sun as it enters its Red Giant Branch phase. Credit: Wikimedia Commons/Fsgregs

Essentially, much attention has been dedicated to whether or not humanity will survive our Sun leaving its main sequence phase. Comparatively, very little research has been conducted on whether or not life itself (and which lifeforms) will be able to survive this change. As such, they considered the most statistically-likely events that would be capable of completely sterilizing an Earth-like planet, and sought to determine what lifeforms could endure them.

As Dr. Loeb told Universe Today via email, their team wanted to consider if there was an extinction-level event that could eliminate all life on Earth (not just humans):

“We wanted to find out how long life may survive on a planet once formed. Most previous studies focused on the survival of humans which are very sensitive to changes in the atmosphere or climate of the Earth and can be eliminated by the impact of an asteroid (nuclear winter) or bad politics.”

What they found was that the species Milnesium tardigradum would survive all potential astrophysical catastrophes. What’s more, they estimated that these creatures will be around for another 10 billion years at least – far longer than what is anticipated for the human race! As Loeb indicates, this was not an outcome that they were expecting.

“To our surprise, tardigrades are likely to survive all astrophysical catastrophes,” he said. “Most likely, the DNA of tardigrades is able to repair itself quickly due to damage encountered by the environment. The process is not fully understood, and there is a group at Harvard University who studies the SNA of tardigrades with the hope of understanding it better.”

Scanning Electron Microscope (SEM) image of Milnesium tardigradum in active state. Credit: Schokraie E/Warnken U/Hotz-Wagenblatt A/Grohme MA/Hengherr S, et al.

To be fair, it has been known for some time that Tardigrades are the most resilient life form on Earth. Not only can they survive for up to 30 years without food or water (half their natural lifespan), they can also survive temperatures of up to 150 °C (302 °F) and as low as -200 °C (-328 °F). They have also shown themselves to be capable of enduring extremes in pressure, ranging from the 6000 atmospheres to the vacuum of open space.

Under these conditions, the research team concluded that they are likely to survive the Sun becoming a red giant and irradiating Earth, and will likely be alive even after the Sun has winked out of existence.  On top of that, tardigrades can even be brought back to life, under the right circumstances. Much like all life on Earth, tradigrades need water to survive, even though they can survive in a dry state for extended periods of time – up to ten years, in fact.

But even after being deprived of water to the point of death, scientists have found that these organisms can be reanimated once water is reintroduced. This was demonstrated in 2007 when a batch of tardigrades was dehydrated before being launched to Low Earth Orbit (LEO). After being exposed to the hard vacuum of space and UV radiation for 10 days, they were returned to Earth and rehydrated – at which point, the majority were revived and able to produce viable embryos.

The team also concluded that other cataclysmic events – such as an asteroid strike, exploding stars (i.e. a supernovae) or gamma ray bursts – pose no existential threat to tardigrades. As Loeb explained:

“We have found that asteroid impacts are capable of boiling off all the oceans on Earth, but only if the asteroid is more massive than 10¹⁸ kg [10,000 trillion metric tons]. Such events are extremely rare and will not happen before the Sun will die; the probability of them happening earlier is less than one part in a million.”

Artist’s concept of a collision between proto-Earth and Theia, believed to happened 4.5 billion years ago. Credit: NASA

In fact, the last time an object large enough to boil the oceans (2 x 10¹⁸ kg) collided with Earth occurred roughly 4.51 billion years ago. On this occasion, Earth was struck by a Mars-sized object named Theia, which is believed to be what caused the formation of the Moon. Today, there are only a dozen known asteroids or dwarf planets in the Solar System that have this kind of mass, and none of them will intersect the Earth’s orbit in the future.

As for supernova, they indicated that an exploding star would need to be 0.14 light-years from Earth in order for it to boil the oceans from its surface. Since the closest star to our Sun (Proxima Centauri) is 4.25  light years away, this scenario is not a foreseeable risk. As for gamma-ray bursts, which are even rarer than supernova, the team determined that they too are too far away from Earth to pose a threat.

The implications of this study are quite fascinating. For one, it reminds us just how fragile human life is compared to basic, microscopic life forms. It also demonstrates that similarly hardy organisms could exist in a variety of locations that we may have once considered too hostile for life. As Dr Rafael Alves Batista, one of the co-authors on the study, said in a University of Oxford press release:

“Without our technology protecting us, humans are a very sensitive species. Subtle changes in our environment impact us dramatically. There are many more resilient species’ on earth. Life on this planet can continue long after humans are gone. Tardigrades are as close to indestructible as it gets on Earth, but it is possible that there are other resilient species examples elsewhere in the Universe. In this context there is a real case for looking for life on Mars and in other areas of the Solar System in general. If Tardigrades are earth’s most resilient species, who knows what else is out there?’”

The tiny Tardigrade: Nature’s toughest creature? Credit: Katexic Publications, unaltered, CC2.0)

And as Dr. Loeb explained, studies like this have potential benefits that go far beyond assessing our own survivability. Not only do they help us understand life’s ability to endure catastrophic events – which is essential to understanding how and where life could emerge in the Universe – but they also offer possibilities on how we might better our own chances of survival.

“We get a better understanding of the conditions under which life will persist,” he said. “In about a billion years, when the Sun will heat up life will cease, but until then it will continue in some form. Understanding the self-repair mechanism of the DNA on tardigrades could potentially help in combating disease for humans as well.”

And all his time, we thought cockroaches were the toughest critters on the planet, what with their ability to withstand a nuclear holocaust. But these eight-legged creatures, which are arguably cuter than cockroaches too, clearly have the market on toughness cornered. We’re just lucky they only get up to 0.5 mm (0.02 in) in size, otherwise we might have something to worry about!

Further Reading: University of Oxford, Scientific Reports

The post Long After Humanity is Gone and the Sun Dies, the Water Bears Will be There appeared first on Universe Today.

This is the One of the Largest Structures We Know of in the Universe

This is the One of the Largest Structures We Know of in the Universe:

The Milky Way Galaxy, which measures 100,000 to 180,000 light years (31 – 55 kiloparsecs) in diameter and contains 100 to 400 billion stars, is so immense that it boggles the mind. And yet, when it comes to the large-scale structure of the Universe, our galaxy is merely a drop in the bucket. Looking farther, astronomers have noted that galaxies form clusters, which in turn form superclusters – the largest known structures in the Universe.

The supercluster in which our galaxy resides is known as the Laniakea Supercluster, which spans 500 million light-years. But thanks to a new study by a team of Indian astronomers, a new supercluster has just been identified that puts all previously known ones to shame. Known as Saraswati, this supercluster is over 650 million light years (200 megaparsecs) in diameter, making it one the largest large-scale structures in the known Universe.

The study, which recently appeared in The Astrophysical Journal under the title “Saraswati: An Extremely Massive ~ 200 Megaparsec Scale Supercluster“, was conducted by astronomers from the Inter University Center for Astronomy & Astrophysics (IUCAA) and the Indian Institute of Science Education and Research (IISER), with assistance provided by a number of Indian universities.

The distribution of galaxies, from Sloan Digital Sky Survey (SDSS), in Saraswati supercluster. Credit: IUCAA

For the sake of their study, the team relied on data obtained by the Sloan Digital Sky Survey (SDSS) to examine the large-scale structure of the Universe. In the past, astronomers have found that the cosmos is hierarchically assembled, with galaxies being arranged in clusters, superclusters, sheets, walls and filaments. These are separated by immense cosmic voids, which together create the vast “Cosmic Web” structure of the Universe.

Superclusters, which are the largest coherent structures in the Cosmic Web, are basically chains of galaxies and galaxy clusters that can extend for hundreds of millions of light years and contain trillions of stars. In the end, the team found a supercluster located about 4 billion (1226 megaparsecs) light-years from Earth – in the constellation Pisces – that is 600 million light-years wide and may contain the mass equivalent of over 20 million billion suns.

They gave this supercluster the name “Saraswati”, the name of an ancient river that played an important role in the emergence of Indian civilization. Saraswait is also the name of a goddess that is worshipped in India today as the keeper of celestial rivers and the goddess of knowledge, music, art, wisdom and nature. This find was particularly surprising, seeing as how Saraswati was older than expected.

Essentially, the supercluster appeared in the SDSS data as it would have when the Universe was roughly 10 billion years old. So not only is Saraswati one of the largest superclusters discovered to date, but its existence raises some serious questions about our current cosmological models. Basically, the predominant model for cosmic evolution does not predict that such a superstructure could exist when the Universe was 10 billion years old.

Diagram of the Lambda-CDM model, which shows cosmic evolution from the Big Bang/Inflation Era and the subsequent expansion of the universe.  Credit: Alex Mittelmann.

Known as the “Cold Dark Matter” model, this theory predicts that small structures (i.e. galaxies) formed first in the Universe and then congregated into larger structures. While variations within this model exist, none predict that something as large as Saraswati could have existed 4 billion years ago. Because of this, the discovery may require astronomers to rethink their theories of how the Universe became what it is today.

To put it simply, the Saraswati supercluster formed at a time when Dark Energy began to dominate structure formation, replacing gravitation as the main force shaping cosmic evolution. As Joydeep Bagchi, a researcher from IUCAA and the lead author of the paper, and co-author Shishir Sankhyayan (of IISER) explained in a IUCAA press release:

‘’We were very surprised to spot this giant wall-like supercluster of galaxies… This supercluster is clearly embedded in a large network of cosmic filaments traced by clusters and large voids. Previously only a few comparatively large superclusters have been reported, for example the ‘Shapley Concentration’ or the ‘Sloan Great Wall’ in the nearby universe, while the ‘Saraswati’ supercluster is far more distant one. Our work will help to shed light on the perplexing question; how such extreme large scale, prominent matter-density enhancements had formed billions of years in the past when the mysterious Dark Energy had just started to dominate structure formation.’’

As such, the discovery of this most-massive of superclusters may shed light on how and when Dark Energy played an important role in supercluster formation. It also opens the door to other cosmological theories that are in competition with the CDM model, which may offer more consistent explanations as to why Saraswati could exist 10 billion years after the Big Bang.

One thing is clear thought: this discovery represents an exciting opportunity for new research into cosmic formation and evolution. And with the aid of new instruments and observational facilities, astronomers will be able to look at Saraswait and other superclusters more closely in the coming years and study just how they effect their cosmic environment.

Further Reading: IUCAA, The Astrophysical Journal

The post This is the One of the Largest Structures We Know of in the Universe appeared first on Universe Today.

Moon Shadow versus Sun Reflection

Moon Shadow versus Sun Reflection:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 July 17



Moon Shadow versus Sun Reflection

Image Credit: Himawari-8, NASA's SVS (GSFC)


Explanation: What are those lights and shadows crossing the Earth? As the featured five-second time-lapse video progresses, a full day on planet Earth is depicted as seen from Japan's Himawari-8 satellite in geostationary orbit high above the Pacific Ocean. The Sun rises to the right and sets to the left, illuminating the half of Earth that is most directly below. A reflected image of the Sun -- a Sun glint -- is visible as a bright spot that moves from right to left. More unusual, though, is the dark spot that moves from the lower left to upper right That is the shadow of the Moon, and it can only appear when the Moon goes directly between the Earth and the Sun. Last year, on the day these images were taken, the most deeply shadowed region experienced a total eclipse of the Sun. Next month a similarly dark shadow will sweep right across the USA.

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Lightning Eclipse from the Planet of the Goats

Lightning Eclipse from the Planet of the Goats:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 July 16

Explanation: Thunderstorms almost spoiled this view of the spectacular 2011 June 15 total lunar eclipse. Instead, storm clouds parted for 10 minutes during the total eclipse phase and lightning bolts contributed to the dramatic sky. Captured with a 30-second exposure the scene also inspired one of the more memorable titles (thanks to the astrophotographer) in APOD's now 22-year history. Of course, the lightning reference clearly makes sense, and the shadow play of the dark lunar eclipse was widely viewed across planet Earth in Europe, Africa, Asia, and Australia. The picture itself, however, was shot from the Greek island of Ikaria at Pezi. That area is known as "the planet of the goats" because of the rough terrain and strange looking rocks.

Chinese Scientists Just Set the Record for the Farthest Quantum Teleportation

Chinese Scientists Just Set the Record for the Farthest Quantum Teleportation:

Credit: sakkmesterke/Shutterstock

Chinese scientists have just shattered a record in teleportation. No, they haven't beamed anyone up to a spaceship. Rather, they sent a packet of information from Tibet to a satellite in orbit, up to 870 miles (1,400 kilometers) above the Earth's surface.

More specifically, the scientists beamed the quantum state of a photon (information about how it is polarized) into orbit.

Not only did the team set a record for quantum teleportation distance, they also showed that one can build a practical system for long-distance quantum communications. Such a communication system would be impossible to eavesdrop on without alerting the users, which would make online communications much more secure.

Experiments like this have been done before, but Howard Wiseman, director of the Center for Quantum Dynamics at Griffith University in Brisbane, Australia, told Live Science in an email that this one expands the possibilities for the technology. [10 Futuristic Technologies 'Star Trek' Fans Would Love to See]

"This is much more difficult, because it is to a rapidly moving target, and you have your quantum detectors way out in space where they have to work without anyone fiddling with them," he said. "It is a big step towards global-scale quantum communication."

Spooky pairs

The experiment takes advantage of one of several phenomena that describes quantum mechanics: entanglement, or "spooky action at a distance," as Albert Einstein called it. When two particles are entangled, they remain connected so that an action performed on one affects the other as well, no matter how far apart the two are. In the same vein, when one measures the state of one particle in the entangled duo, you'd automatically know the state of the second. Physicists call the states "correlated," because if one particle — a photon, for example — is in an "up" state, its entangled partner will be in a "down" state — a kind of mirror image. (Strictly speaking, there are four possible combinations for the two particles to be in).

The weird part is that once the state of the first particle is measured, the second one somehow "knows" what state it should be in. The information seems to travel instantaneously, without a speed-of-light limit. [8 Ways You Can See Einstein's Theory of Relativity in Real Life]

Teleporting information

In June, the same researchers reported another feat in quantum teleportation: They sent entangled photons from the Micius satellite to two ground stations over distances between 994 miles and 1,490 miles (1,600 and 2,400 km), depending on the location of the satellite in its orbit. While this experiment showed that entanglement can happen over long distances, the new experiment uses that entanglement to transmit a photon's quantum state to a distant location.

In their latest experiment, the Chinese team, led by Ji-Gang Ren at the University of Science and Technology in Shanghai, fired a laser from a ground station in Tibet to a satellite in orbit. That laser beam carried a photon entangled with another photon on the ground. They then entangled the photon on the ground with a third photon, and measured their quantum states. But the scientists didn't actually reveal the states themselves. They just asked whether their states (in this case, their vertical or horizontal polarizations) were the same or different. There are four possible combinations: vertical-vertical, vertical-horizontal, horizontal-vertical and horizontal-horizontal. Since the states of the particles on the ground were correlated with the one on the satellite, an observer looking at the satellite's photon, meanwhile, would know that that photon has to be in one of four possible states that correlate with the two photons on the ground.

If there were a person riding in the satellite, once they were told that the states of the ground-based photons were the same or different, they would know enough to be able reconstruct the state of the ground-based photons and to duplicate it in their single photon on board. The photons on the ground would have had their quantum state teleported to orbit.

While it sounds like information is traveling faster than light, there's no way to use this property as an instantaneous messaging system. That's because even though the states of entangled particles are correlated, you can't know what they are before you measure them, nor can you control the state.

But what entangled particles can do is act as perfect authenticators for messages. The reason is that the act of observing a particle changes its behavior. If an eavesdropper were trying to intercept the transmission between the satellite and the ground in this recent experiment, the quantum states of the photons (as measured by the scientists) would not be correctly correlated.

The Chinese team managed to make entanglement work over distances of 310 miles (500 km) to 870 miles (1,400 km), the maximum distance to the satellite. This is farther than anyone has ever managed to send entangled states. Entangled photons can't interact with anything else on the way to their destination, because once they do, their states have been "observed" – revealed by the interaction. Hence, the teleportation doesn't work if the photons are observed before they get to their destination. When scientists conduct experiments like this one, they don't just send single photons, one at a time; to get the measurements they want, they need to send lots of them. Even in the vacuum of space, out of millions of photons sent, the satellite was only able to reliably receive 911 of them, according to the study. [Infographic: How Quantum Entanglement Works]

If these same photons were sent over fiber-optic cables, rather than through space, the connection between the photons would be destroyed by interference from factors such as heat and vibration, or even random interactions with the cable. As such, it could take 380 billion years to get a measurement from an entangled photon. A satellite, on the other hand, is outside of the atmosphere, and there's much less chance of the entangled photon getting spoiled.

"With fiber you lose many of the photons," said Bill Munro, a senior research scientist at NTT's basic research laboratory, in an interview with Live Science. Beaming photons to orbit means that you could build an actual communications system. "You could beam from China to Washington or New York." The problem of reducing the interference with the signals and getting more photons through, Munro said, is a technical and engineering problem that can be solved.

Both Munro and Wiseman noted that often people think of teleportation as moving an actual object (or a photon) form one place to another. "People have this 'Star Trek' approach," Munro said. "They think of atoms being teleported. What we're moving is information from one [quantum] bit to another [quantum] bit. There's no matter — only information. That's hard to get your head around."

The study appeared in the ArXiv on July 4.

Originally published on Live Science.

New 'Star Wars: The Last Jedi' Footage Unveiled at D23 Expo

New 'Star Wars: The Last Jedi' Footage Unveiled at D23 Expo:

Saturday at Disney's Live Action panel  at D23, Lucasfilm debuted a behind the scenes footage reel from December's "Star Wars: The Last Jedi" with new images from the film.

Check it out!

"Star Wars: The Last Jedi " opens in theaters on Dec. 15.

Originally published on our sister site Newsarama.

Visualization of the August 21, 2017 Total Solar Eclipse

Visualization of the August 21, 2017 Total Solar Eclipse: On August 21, 2017, the Earth will cross the shadow of the moon, creating a total solar eclipse. Eclipses happen about every six months, but this one is special. For the first time in almost 40 years, the path of the moon's shadow passes through the continental United States.

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Hubble Uses Gravitational Lens to Capture Disk Galaxy

Hubble Uses Gravitational Lens to Capture Disk Galaxy: By combining the power of a "natural lens" in space with the capability of NASA's Hubble Space Telescope, astronomers made a surprising discovery—the first example of a compact yet massive, fast-spinning, disk-shaped galaxy that stopped making stars only a few billion years after the big bang.

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Saturnian Dawn

Saturnian Dawn: NASA's Cassini spacecraft peers toward a sliver of Saturn's sunlit atmosphere while the icy rings stretch across the foreground as a dark band.

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Starry Night and Aurora

Starry Night and Aurora: Expedition 52 Flight Engineer Jack Fischer of NASA photographed the glowing nighttime lights of an aurora from his vantage point in the International Space Station's cupola module on June 19, 2017. Part of the station's solar array is also visible.

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The ‘Face’ of Jupiter

The ‘Face’ of Jupiter: JunoCam images aren’t just for art and science – sometimes they are processed to bring a chuckle.

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Dragon Returns Space Station Science to Earth

Dragon Returns Space Station Science to Earth: NASA astronaut Jack Fischer photographed the SpaceX Dragon capsule as it reentered Earth's atmosphere before splashing down in the Pacific Ocean west of Baja California at 8:12 a.m. EDT, July 3, 2017. Fischer commented, "Beautiful expanse of stars-but the “long” orange one is SpaceX-11 reentering!"

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Winds Trigger Pond Growth

Winds Trigger Pond Growth: Wind is a force to be reckoned with. It can stir up monsoons, carry dust thousands of miles, and sculpt rock into sinuous arches. But sometimes, the effects of wind go unnoticed for years, like when it carves away slowly at the edges of a pond.

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Dawn’s Early Light

Dawn’s Early Light: The light of a new day on Saturn illuminates the planet’s wavy cloud patterns and the smooth arcs of the vast rings.

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Jupiter’s Great Red Spot (Enhanced Color)

Jupiter’s Great Red Spot (Enhanced Color): This enhanced-color image of Jupiter’s Great Red Spot was created by citizen scientist Gerald Eichstädt using data from the JunoCam imager on NASA’s Juno spacecraft.

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Hubble Traps a Lynx Barred Spiral

Hubble Traps a Lynx Barred Spiral: NGC 2500 is a particular kind of spiral galaxy known as a barred spiral, its wispy arms swirling out from a bright, elongated core.

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Close up of the Great Red Spot

Close up of the Great Red Spot:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2017 July 15

Close-up of The Great Red Spot

Image Credit: NASA, Juno, SwRI, MSSS, Gerald Eichstadt, Sean Doran


Explanation: On July 11, the Juno spacecraft once again swung near to Jupiter's turbulent cloud tops in its looping 53 day orbit around the Solar System's ruling gas giant. About 11 minutes after perijove 7, its closest approach on this orbit, it passed directly above Jupiter's Great Red Spot. During the much anticipated fly over, it captured this close-up image data from a distance of less than 10,000 kilometers. The raw JunoCam data was subsequently processed by citizen scientists. Very long-lived but found to be shrinking, the Solar System's largest storm system was measure to be 16,350 kilometers wide on April 15. That's about 1.3 times the diameter of planet Earth.

Tomorrow's picture: planet of the goats

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Even Though Red Dwarfs Have Long Lasting Habitable Zones, They’d be Brutal to Life

Even Though Red Dwarfs Have Long Lasting Habitable Zones, They’d be Brutal to Life:

Ever since scientists confirmed the existence of seven terrestrial planets orbiting TRAPPIST-1, this system has been a focal point of interest for astronomers. Given its proximity to Earth (just 39.5 light-years light-years away), and the fact that three of its planets orbit within the star’s “Goldilocks Zone“, this system has been an ideal location for learning more about the potential habitability of red dwarf stars systems.

This is especially important since the majority of stars in our galaxy are red dwarfs (aka. M-type dwarf stars). Unfortunately, not all of the research has been reassuring. For example, two recent studies performed by two separate teams from Harvard-Smithsonian Center for Astrophysics (CfA) indicate that the odds finding life in this system are less likely than generally thought.

The first study, titled “Physical Constraints on the Likelihood of Life on Exoplanets“, sought to address how radiation and stellar wind would affect any planets located within TRAPPIST-1s habitable zone. Towards this end, the study’s authors – Professors Manasvi Lingam and Avi Loeb – constructed a model that considered how certain factors would affect conditions on the surface of these planets.

This artist’s concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances. Credits: NASA/JPL-Caltech

This model took into account how the planets distance from their star would affect surface temperatures and atmospheric loss, and how this might affect the changes life would have to emerge over time. As Dr. Loeb told Universe Today via email:

“We considered the erosion of the atmosphere of the planets due to the stellar wind and the role of temperature on ecological and evolutionary processes. The habitable zone around the faint dwarf star TRAPPIST-1 is several tens of times closer in than for the Sun, hence the pressure of the stellar wind is several orders of magnitude higher than on Earth. Since life as we know it requires liquid water and liquid water requires an atmosphere, it is less likely that life exists around TRAPPIST-1 than in the solar system.”

Essentially, Dr. Lingam and Dr, Loeb found that planets in the TRAPPIST-1 system would be barraged by UV radiation with an intensity far greater than that experienced by Earth. This is a well-known hazard when it comes to red dwarf stars, which are variable and unstable when compared to our own Sun. They concluded that compared to Earth, the chances of complex life existing on planets within TRAPPIST-1’s habitable zone were less than 1%.

“We showed that Earth-sized exoplanets in the habitable zone around M-dwarfs display much lower prospects of being habitable relative to Earth, owing to the higher incident ultraviolet fluxes and closer distances to the host star,” said Loeb. “This applies to the recently discovered exoplanets in the vicinity of the Sun, Proxima b (the nearest star four light years away) and TRAPPIST-1 (ten times farther), which we find to be several orders of magnitude smaller than that of Earth.”

Three of the TRAPPIST-1 planets – TRAPPIST-1e, f and g – dwell in their star’s so-called “habitable zone. CreditL NASA/JPL

The second study – “The Threatening Environment of the TRAPPIST-1 Planets“, which was recently published in The Astrophysical Journal Letters – was produced by a team from the CfA and the Lowell Center for Space Science and Technology at the University of Massachusetts. Led by Dr. Cecilia Garraffo of the CfA, the team considered another potential threat to life in this system.

Essentially, the team found that TRAPPIST-1, like our Sun, sends streams of charged particles outwards into space – i.e. stellar wind. Within the Solar System, this wind exerts force on the planets and can have the effect of stripping away their atmospheres. Whereas Earth’s atmosphere is protected by its magnetic field, planets like Mars are not – hence why it lost the majority of its atmosphere to space over the course of hundreds of million of years.

As the research team found, when it comes to TRAPPIST-1, this stream exerts a force on its planets that is between 1,000 to 100,000 times greater than what Earth experiences from solar wind. Furthermore, they argue that TRAPPIST-1’s magnetic field is likely connected to the magnetic fields of the planets that orbit around it, which would allow particles from the star to directly flow onto the planet’s atmosphere.

Illustration showing the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Credits: NASA/JPL-Caltech

In other words, if TRAPPIST-1’s planets do have magnetic fields, they will not afford them any protection. So if the flow of charged particles is strong enough, it could strip these planets’ atmospheres away, thus rendering them uninhabitable. As Garraffo put it:

“The Earth’s magnetic field acts like a shield against the potentially damaging effects of the solar wind. If Earth were much closer to the Sun and subjected to the onslaught of particles like the TRAPPIST-1 star delivers, our planetary shield would fail pretty quickly.”

As you can imagine, this is not exactly good news for those who were hoping that the TRAPPIST-1 system would hold the first evidence of life beyond our Solar System. Between the fact that its planets orbit a star that emits varying degrees of intense radiation, and the proximity its seven planets have to the star itself, the odds of life emerging on any planet within it’s “habitable zone” are not significant.

The findings of the second study are particularly significant in light of other recent studies. In the past, Prof. Loeb and a team from the University of Chicago have both addressed the possibility that the TRAPPIST-1 system’s seven planets – which are relatively close together – are well-suited to lithopanspermia. In short, they determined that given their close proximity to each other, bacteria could be transferred from one planet to the next via asteroids.

An artist’s depiction of planets transiting a red dwarf star in the TRAPPIST-1 System. Credit: NASA/ESA/STScl

But if the proximity of these planets also means that they are unlikely to retain their atmospheres in the face of stellar wind, the likelihood of lithopanspermia may be a moot point. However, before anyone gets to thinking that this is bad news as far as the hunt for life goes, it is important to note that this study does not rule out the possibility of life emerging in all red dwarf star systems.

As Dr. Jeremy Drake – a senior astrophysicist from the CfA and one of Garraffo’s co-authors – indicated, the results of their study simply mean that we need to cast a wide net when searching for life in the Universe.  “We’re definitely not saying people should give up searching for life around red dwarf stars,” he said. “But our work and the work of our colleagues shows we should also target as many stars as possible that are more like the Sun.”

And as Dr. Leob himself has indicated in the past, red dwarf stars are still the most statistically-likely place to find habitable worlds:

“By surveying the habitability of the Universe throughout cosmic history from the birth of the first stars 30 million years after the Big Bang to the death of the last stars in 10 trillion years, one reaches the conclusion that unless habitability around low-mass stars is suppressed, life is most likely to exist near red dwarf stars like Proxima Centauri or TRAPPIST-1 trillions of years from now.”

If there is one takeaway from these studies, it is that the existence of life within a star system does not simply require planets orbiting within the circumstellar habitable zones. The nature of the stars themselves and the role played by solar wind and magnetic fields also have to be taken into account, since they can mean the difference between a life-bearing planet and a sterile ball of rock!

Further Reading: CfA, International Journal of Astrobiology, The Astrophysical Journal Letters.

The post Even Though Red Dwarfs Have Long Lasting Habitable Zones, They’d be Brutal to Life appeared first on Universe Today.

Two Years Ago Today: It Was a Clear Day on Pluto When New Horizons Flew By

Two Years Ago Today: It Was a Clear Day on Pluto When New Horizons Flew By:

It was two years ago this morning that we awoke to see the now iconic image of Pluto that the New Horizons spacecraft had sent to Earth during the night. You, of course, know the picture I’m talking about – the one with a clear view of the giant heart-shaped region on the distant, little world (see above).

This image was taken just 16 hours before the spacecraft would make its closest approach to Pluto. Then, during that seemingly brief flyby (after traveling nine-and-a-half years and 3 billion miles to get there), the spacecraft gathered as much data as possible and we’ve been swooning over the images and pondering the findings from New Horizons ever since.

“This is what we came for – these images, spectra and other data types that are helping us understand the origin and the evolution of the Pluto system for the first time,” New Horizons principal investigator Alan Stern told me last year. “We’re seeing that Pluto is a scientific wonderland. The images have been just magical. It’s breathtaking.”

See a stunning new video created from flbyby footage in honor of the two-year anniversary of the flyby:



All the images have shown us that Pluto is a complex world with incredible diversity, in its geology and also in its atmosphere.

While the iconic “heart” image shows a clear and cloudless view of Pluto, a later image showed incredible detail of Pluto’s hazy atmosphere, with over two dozen concentric layers that stretches more than 200 km high in Pluto’s sky.

With all those layers and all that haze, could there be clouds on Pluto too?

The smooth expanse of the informally named Sputnik Planum (right) is flanked to the west (left) by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the skyline. The backlighting highlights more than a dozen layers of haze in Pluto’s tenuous but distended atmosphere. Credit: NASA/JHUAPL/SwRI.

This is a question Stern and his fellow scientists have been asking for a long time, actually, as they have been studying Pluto for decades from afar. Now with data from New Horizons, they’ve been able to look closer. While Stern and his colleagues have been discussing how they found possible clouds on Pluto for a few months, they have now detailed their findings in a paper published last month.

“Numerous planets in our solar system, including Venus, Earth, Mars, Titan, and all four of the giant planets possess atmospheres that contain clouds, i.e., discrete atmospheric condensation structures,” the team wrote in their paper. “This said, it has long been known that Pluto’s current atmosphere is not extensively cloudy at optical or infrared wavelengths.”

They explained that evidence for this came primarily from the “high amplitude and temporal stability of Pluto’s lightcurve,” however, because no high spatial resolution imagery of Pluto was possible before New Horizons, it remained to be seen if clouds occur over a small fraction of Pluto’s surface area.

But now with flyby images in hand, the team set out to do searches for clouds on Pluto, looking at all available imagery from the Long Range Reconnaissance Imager and the Multispectral Visible Imaging Camera, looking at both the disk of Pluto and near and on the limb. Since an automated cloud search was nearly impossible, it was all done by visual inspection of the images by the scientists.

They looked for features in the atmosphere that including brightness, fuzzy or fluffy-looking edges and isolated borders.

Seven Possible Cloud Candidates (PCCs) identified by the New Horizons team. Two of these images (3, 4) were taken by MVIC; the other five (1, 2, 5,
6, 7) were taken by LORRI. Arrows indicate each PCC. Credit: Stern et al, 2017.

In all, they found seven bright, discrete possible cloud candidates. The seven candidates share several different attributes including small size, low altitude, they all were visible either early or late in the day local time, and were only visible at oblique geometry – which is basically a sideways look from the spacecraft.

Also, several cloud candidates also coincided with brighter surface features below, so the team is still pondering the correlation.

“The seven candidates are all similar in that they are very low altitude,” Stern said last fall at the Division of Planetary Sciences meeting, “and they are all low-lying, isolated small features, so no broad cloud decks or fields. When we map them over the surface, they all lie near the terminator, so they occur near dawn or dusk. This is all suggestive they are clouds because low-lying regions and dawn or dusk provide cooler conditions where clouds may occur.”

While haze was detected as high as 220 km, the possible clouds were found at very low altitudes. Stern told Universe Today that these possible, rare condensation clouds could be made of ethane, acetylene, hydrogen cyanide or methane under the right conditions. Stern added these clouds are probably short-lived phenomena – again, likely occurring only at dawn or dusk. A day on Pluto is 6.4 days on Earth.

But all in all, they concluded that at the current time Pluto’s atmosphere is almost entirely free of clouds – in fact the dwarf planet’s sky was 99% cloud free the day that New Horizons whizzed by.

“But if there are clouds, it would mean the weather on Pluto is even more complex than we imagined,” Stern said last year.

The seven cloud candidates cannot be confirmed as clouds because none are in the region where there was stereo imaging or other available ways to cross-check it. They concluded that further modeling would be needed, but specifically a Pluto orbiter mission would be the only way to “search for clouds more thoroughly than time and space and was possible during the brief reconnaissance flyby by New Horizons.”

If you’re dreaming of a Pluto orbiter, you can read about some possibilities of how to do it in our article from May of this year.

The post Two Years Ago Today: It Was a Clear Day on Pluto When New Horizons Flew By appeared first on Universe Today.

Evidence Mounts for the Existence of Planet Nine

Evidence Mounts for the Existence of Planet Nine:

In January of 2016, astronomers Mike Brown and Konstantin Batygin published the first evidence that there might be another planet in our Solar System. Known as “Planet 9”, this hypothetical body was estimated to be about 10 times as massive as Earth and to orbit that our Sun at an average distance of 700 AU. Since that time, multiple studies have been produced that either support or cast doubt on the existence of Planet 9.

While some argue that the orbits of certain Trans-Neptunian Objects (TNOs) are proof of Planet 9, others argue that these studies suffer from an observational bias. The latest study, which comes from a pair of astronomers from the Complutense University of Madrid (UCM), offers a fresh perspective that could settle the debate. Using a new technique that focuses on extreme TNOs (ETNOs), they believe the case for Planet 9 can be made.

Extreme Trans-Neptunian Objects are those that orbit our Sun at average distances greater than 150 AU, and therefore never cross Neptune’s orbit. As the UMC team indicate in their study, which was recently published in the Monthly Notices of the Royal Astronomical Society, the distances between the ETNOs nodes and the Sun may point the way towards Planet 9.

Artist’s impression of what the theoretical Planet 9 could look like. Credit: NASA

These nodes are the two points at which the orbit of a celestial body crosses the plane of the Solar System. It is at these points that the chances of interacting with other bodies in the Solar System is the greatest, and hence where ETNOs are most likely to experience a drastic change in their orbits (or a collision). By measuring where these nodes are, the team believed they could tell if the ETNOs are being perturbed by another object in the area.

As Carlos de la Fuente Marcos, one of the authors on the study, explained in an interview with The Information and Scientific News Service (SINC):

“If there is nothing to perturb them, the nodes of these extreme trans-Neptunian objects should be uniformly distributed, as there is nothing for them to avoid, but if there are one or more perturbers, two situations may arise. One possibility is that the ETNOs are stable, and in this case they would tend to have their nodes away from the path of possible perturbers, he adds, but if they are unstable they would behave as the comets that interact with Jupiter do, that is tending to have one of the nodes close to the orbit of the hypothetical perturber”.

For the sake of their research, Doctors Carlos and Raul de la Fuente Marcos conducted calculations and data mining to analyze the nodes of 28 ETNOs and 24 extreme Centaurs (which also orbit the Sun at average distances of more than 150 AUs). What they noticed was that these two populations became clustered at certain distances from the Sun, and also noted a correlation between the positions of the nodes and the inclination of the objects.

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign

This latter find was especially unexpected, and led them to conclude that the orbits of these populations were being affected by the presence of another body – much in the same way that the orbits of comets within our Solar System have been found to be affected by the way they interact with Jupiter. As De la Fuente Marcos emphasized:

“Assuming that the ETNOs are dynamically similar to the comets that interact with Jupiter, we interpret these results as signs of the presence of a planet that is actively interacting with them in a range of distances from 300 to 400 AU. We believe that what we are seeing here cannot be attributed to the presence of observational bias”.

As already mentioned, previous studies that have challenged the existence of Planet 9 cited how the study of TNOs have suffered from an observational bias. Basically, they have claimed that these studies made systematic errors in how they calculated the orientations in the orbits of TNOs, in large part because they had all been directed towards the same region of the sky.

By looking at the nodal distances of ETNOs, which depend on the size and shape of their orbits, this most recent study offers the first evidence of Planet 9’s existence that is relatively free of this bias. At the moment, only 28 ETNOs are known, but the authors are confident that the discovery of more – and the analysis of their nodes – will confirm their observations and place further constraints on the orbit of Planet 9.

A planetary mass object the size of Mars would be sufficient to produce the observed perturbations in the distant Kuiper Belt. Credit: Heather Roper/LPL

In addition, the pair of astronomers offered some thoughts on recent work that has suggested the possible existence of a Planet 10. While their study does not take into account the existence of a Mars-sized body – which is said to be responsible for an observable “warp” in the Kuiper Belt – they acknowledge that there is compelling evidence that such a planet-sized body exists. As de la Fuente Marcos said:

“Given the current definition of planet, this other mysterious object may not be a true planet, even if it has a size similar to that of the Earth, as it could be surrounded by huge asteroids or dwarf planets. In any case, we are convinced that Volk and Malhotra’s work has found solid evidence of the presence of a massive body beyond the so-called Kuiper Cliff, the furthest point of the trans-Neptunian belt, at some 50 AU from the Sun, and we hope to be able to present soon a new work which also supports its existence”.

It seems that the outer Solar System is getting more crowded with every passing year. And these planets, if and when they are confirmed, are likely to trigger another debate about which Solar bodies are rightly designated as planets and which ones aren’t. If you thought the “planetary debate” was controversial and divisive before, I recommend staying away from astronomy forums in the coming years!

Further Reading: SINC. MNRAS

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