Posted on by Evan Gough

Don’t Want Aliens Dropping By? Engage Laser Cloaking Device

Lasers like this one, at the VLT in Paranal, help counteract the blurring effect of the atmosphere. Powerful arrays of much larger lasers could hide our presence from aliens. (ESO/Y. Beletsky)
Lasers like this one, at the VLT in Paranal, help counteract the blurring effect of the atmosphere. Powerful arrays of much larger lasers could hide our presence from aliens. (ESO/Y. Beletsky)

Of course we all know that aliens want to take over Earth. It’s in all the movies. And after they take over, they could do whatever they want to us puny, weak Earthlings. Enslavement? Yup. Forced breeding programs? Sure. Lay eggs in our bellies and consume our guts for their first meal? Why not.

But here at Universe Today, we’re science-minded types. We love the science fiction, but don’t take it too seriously. But someone we do take seriously when he has something to tell us is Stephen Hawking. And when he warned us that aliens might want to conquer and colonize us, it lent gravity to the whole discussion around contact with aliens. Should we reach out to alien civilizations? Will we be safe if they find us? Or should we try to conceal our presence?

If we choose concealment, then a new paper from two astronomers at New York’s Columbia University have good news for humanity. The authors of the paper, Professor David Kipping and graduate student Alex Teachey, say that lasers could be used to hide Earth from alien prying eyes.

At the heart of this whole idea are transits. When a planet passes in between its star and a distant observer, the star’s light is dimmed, and that’s called a transit. This is how the Kepler spacecraft detects exo-planets, and it’s been remarkably successful. If alien species are using the same method, which makes sense, then Earth would be easily detectable in the Sun’s habitable zone.

According to Kipping and Teachey, lasers could be used to mask this effect. A 30 MW laser would be enough to counter the dimming effect of Earth’s transit in front of the Sun. And it would only need to be turned on for 10 hours, once every year, since that’s how long Earth’s transit takes.

But that would only take care of the dimming effect in visible light. To counter-act the transit dimming across the whole electromagnetic spectrum would require much more energy: a 250 MW cloak of lasers tuned all across the spectrum. But there might be a middle way.

According to an interview with the paper’s authors in Science Daily, it might take only 160 MW of lasers to mask biological signatures in the atmosphere. Any prying alien eyes would not notice that life had ever come into being on Earth.

Should we decide that we do indeed want to be colonized, or forced to take part in breeding programs, or be enslaved, then the same system of lasers could be used to amplify the transit effect. This would make it easier, rather than harder, for aliens to detect us. In fact, according to the authors, these lasers could even be used to communicate with aliens, by transmitting information.

Of course, there’s one other element to all this. For this to work, we have to know where to aim the lasers, which means we have to know where the alien civilization is. And if we’re worried about them coming to get us, they will have more advanced technology than us. And if they have more advanced technology than us, they will for sure already have laser cloaking like the type talked about here.

So who’ll be the first to blink, and turn off their laser cloaking and allow detection?

You first, aliens.

Posted on by Evan Gough

Andromeda’s First Spinning Neutron Star Found

Andromeda's spinning neutron star. Though astronomers think there are over 100 million of these objects in the Milky Way, this is the first one found in Andromeda. Image: ESA/XMM Newton.
Andromeda's spinning neutron star. Though astronomers think there are over 100 million of these objects in the Milky Way, this is the first one found in Andromeda. Image: ESA/XMM Newton.

On a clear night, away from the bright lights of a city, you can see the smudge of the Andromeda galaxy with the naked eye. With a backyard telescope, you can take a good look at the Milky Way’s sister galaxy. With powerful observatories, it’s possible to see deep inside Andromeda, which is what astronomers have been doing for decades.

Now, astronomers combing through data from the ESA’s XMM Newton space telescope have found something rare, at least for Andromeda; a spinning neutron star. Though these objects are common in the Milky Way, (astronomers think there are over 100 million of them) this is the first one discovered in Andromeda.

A neutron star is the remnant of a massive star that went supernova. They are the smallest and most dense stellar objects known. Neutron stars are made entirely of neutrons, and have no electrical charge. They spin rapidly, and can emit electromagnetic energy.

If the neutron star is oriented toward Earth in just the right way, we can detect their emitted energy as pulses. Think of them as lighthouses, with their beam sweeping across Earth. The pulses of energy were first detected in 1967, and given the name pulsar.” We actually discovered pulsars before we knew that neutron stars existed.

Many neutron stars, including this one, exist in binary systems, which makes them easier to detect. They cannibalize their companion star, drawing gas from the companion into their magnetic fields. As they do so, they emit high energy pulses of X-ray energy.

The star in question, which astronomers, with their characteristic flair for language, have named 3XMM J004301.4+413017, spins rapidly: once every 1.2 seconds. It’s neighbouring star orbits it once every 1.3 days. While these facts are known, a more detailed understanding of the star will have to wait for more analysis. But 3XMM J004301.4+413017 does appear to be an exotic object.

“It could be what we call a ‘peculiar low-mass X-ray binary pulsar’ – in which the companion star is less massive than our Sun – or alternatively an intermediate-mass binary system, with a companion of about two solar masses,” says Paolo Esposito of INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan, Italy. “We need to acquire more observations of the pulsar and its companion to help determine which scenario is more likely.”

“We’re in a better position now to uncover more objects like this in Andromeda, both with XMM-Newton and with future missions such as ESA’s next-generation high-energy observatory, Athena,” added Norbert Schartel, ESA’s XMM-Newton project scientist.

This discovery is a result of EXTraS, a European Project that combs through XMM Newton data. “EXTraS discovery of an 1.2-s X-ray pulsar in M31” by P. Esposito et al, is published in the Monthly Notices of the Royal Astronomical Society, Volume 457, pp L5-L9, Issue 1 March 21, 2016.

Posted on by Evan Gough

Inflatable Space Habitat To Be Tested On The ISS

The Bigelow Expandable Activity Module (BEAM) will be launched onboard a SpaceX Dragon on Friday April 8th for a 2-year mission. Astronauts will test the module during that time. Image Bigelow Aerospace.
The Bigelow Expandable Activity Module (BEAM) will be launched onboard a SpaceX Dragon on Friday April 8th for a 2-year mission. Astronauts will test the module during that time. Image Bigelow Aerospace.

Space habitats have long been an object of fascination for thinkers, dreamers, and engineers. Science fiction is littered with space habitats, whether in books or movies. And their designs have ranged from titanic, uber-engineered types to fanciful, organic types.

Bigelow Aerospace is one company that is focused on creating affordable, practical space habitats. Inflatability is the name of the game for Bigelow, and now, one of their habitat modules is going to be tested on the ISS for a 2-year period. The BEAM, or Bigelow Expandable Activity Module, will be launched aboard a SpaceX Dragon on Friday April 8th, for a 2-day journey to the ISS.

The BEAM travels as an 8 foot bundle, but once it’s attached to the ISS, and inflated by astronauts, it will be large enough to hold a car. However, astronauts won’t be living inside it; rather, the BEAM will be tested for 2 years to see how it holds up. The objectives for this 2 year mission include:

  • Demonstrating launch and deployment, as well as folding and packing techniques.
  • Determining radiation protection capability.
  • Demonstrating design performance such as thermal, structural, mechanical durability, long-term leak performance, etc.
  • Increasing Technology Readiness Level (TRL) of expandable habitat technology
The BEAM with human figure for scale. Image: Bigelow Aerospace.
The BEAM with human figure for scale. Image: Bigelow Aerospace.

“The International Space Station is a uniquely suited test bed to demonstrate innovative exploration technologies like the BEAM,” said William Gerstenmaier, associate administrator for human exploration and operations at NASA Headquarters in Washington. “As we venture deeper into space on the path to Mars, habitats that allow for long-duration stays in space will be a critical capability. Using the station’s resources, we’ll learn how humans can work effectively with this technology in space, as we continue to advance our understanding in all aspects for long-duration spaceflight aboard the orbiting laboratory.”

The obvious risk to an inflatable space habitat is puncturing; not only from meteoroids, but from the growing population of space junk that inhabits Earth’s orbit.  But BEAM is designed with this hazard in mind. It’s a thick-walled design, made from multiple layers of fabric similar to Kevlar. As far as space junk goes, BEAM should be impenetrable.

The BEAM is just a test module. It will hold only monitoring equipment, and will be entered by astronauts retrieving data and performing inspections. Bigelow Aerospace’s design for a usable habitat is the B330, a module large enough for 6 occupants, with a projected lifespan of 20 years. Test results from BEAM’s 2 years in space will help refine the design of the B330.

After its 2 years are up, BEAM will be released from the ISS and will be destroyed when it enters Earth’s atmosphere.

Posted on by Evan Gough

Japan’s Black Hole Telescope Is In Trouble

An artist's drawing of Japan's Hitomi observatory. Image Credit: JAXA/Akihiro Ikeshita
An artist's drawing of Japan's Hitomi observatory. Image Credit: JAXA/Akihiro Ikeshita

The Japanese Aerospace Exploration Agency (JAXA) has lost contact with its X-ray Astronomy Satellite Hitomi (ASTRO-H.) Hitomi was launched on February 17th, for a 3-year mission to study black holes. But now that mission appears to be in jeopardy.

Hitomi is a collaboration between JAXA and NASA. Its mission was to investigate how galaxy clusters were formed and influenced by dark matter and dark energy, and to understand how super-massive black holes form and evolve at the center of galaxies. Hitomi was also to “unearth the physical laws governing extreme conditions in neutron stars and black holes,” according to JAXA.

Japan has managed two very short communications with Hitomi, but they were very brief, and JAXA has not been able to determine the nature of the problem. Now, JSpOC, the US Joint Space Operations Center, say they have detected debris in the vicinity of Hitomi, and in a press release this morning (March 29th), JAXA says “it is estimated that Hitomi separated to five pieces at about 10:42 a.m.”

Hitomi was going to be an important contribution to the fleet of space telescopes used by astrophysicists and cosmologists. It has a cutting edge instrument called the X-ray micro-calorimeter, which would have observed X-rays from space with the greatest sensitivity of any instrument so far. If all that is lost, it will be quite a blow.

There’s no definitive word yet on what exactly has happened to Hitomi. Japan is using ground stations in different parts of the world to try to communicate with their observatory. It’s important to note that there is no agreement that the craft has broken apart. The press releases are translations from Japanese to English, so the exact meaning of “separated to five pieces” is unclear.

It’s possible that there was a small explosion of some sort, and that some debris from that explosion is in the vicinity of Hitomi. It’s also possible that JAXA will re-establish communications with the craft as time goes on.

Other observatories have suffered serious problems, and have eventually been brought back under control and completed their missions. The ESA/NASA Solar and Heliospheric Observatory (SOHO) suffered serious problems at the beginning of its mission in 1995, entering emergency mode 3 times before all contact was lost. Eventually, SOHO was brought under control, and what was supposed to be a 2-year mission has lasted 20.

Universe Today will be following this story to see if Hitomi can be made operational. For readers wanting to know more about Hitomi’s mission, read JAXA’s excellent Hitomi press kit.

Posted on by Evan Gough

The Moon’s Other Axis

A six degree True Polar Wander occurred on the Moon due to ancient volcanic activity. Image: University of Arizona/James Tuttle Keane
A six degree True Polar Wander occurred on the Moon due to ancient volcanic activity. Image: University of Arizona/James Tuttle Keane

It’s tempting to think that the Moon never changes. You can spend your whole life looking at it, and see no evidence of change whatsoever. In fact, the ancients thought the whole Universe was unchanging.

You may have heard of a man named Aristotle. He thought the Universe was eternal and unchanging. Obviously, with our knowledge of the Big Bang, stellar evolution, and planetary formation, we know better. Still, the placid and unchanging face of the Moon can tempt us into thinking astronomers are making up all this evolving universe stuff.

But now, according to a new paper in Nature, the Moon’s axis of rotation is different now than it was billions of years ago. Not only that, but volcanoes may been responsible for it. Volcanoes! On our placid little Moon.

The clue to this lunar True Polar Wander (TPW) is in the water ice locked in the shadows of craters on the Moon. When hydrogen was discovered on the surface of the Moon in the 1990s by the Lunar Prospector probe, scientists suspected that they would eventually find water ice. Subsequent missions proved the presence of water ice, especially in craters near the polar regions. But the distribution of that water-ice wasn’t uniform.

You would expect to see ice uniformly distributed in the shadows of craters in the polar regions, but that’s not what scientists have found. Instead, some craters had no evidence of ice at all, which led the team behind this paper to conclude that these ice-free craters must have been exposed to the Sun at some point. What else would explain it?

The way that the ice in these craters is distributed forms two trails that lead away from each pole. They’re mirror images of each other, but they don’t conform with the Moon’s current axis of rotation, which is what led the team to conclude that the Moon underwent a 6 degree TPW billions of years ago.

The paper also highlights the age of the water on the Moon. Since the TPW, and the melting of some of the ice as a result of it, occurred some billions of years ago, then the water ice that is still frozen in the shadows of some of the Moon’s craters must be ancient. According to the paper, its existence records the “early delivery of water to the inner Solar System.” Hopefully, a future mission will return a sample of this ancient water for detailed study.

But even more interesting than the age of the ice in the craters and the TPW, to me anyways, is what is purported to have caused it. The team behind the paper reports that volcanic activity on the Moon in the Procellarum region, which was most active in the early history of the Moon, moved a substantial amount of material and “altered the density structure of the Moon.” This alteration would have changed the moments of inertia on the Moon, resulting in a TPW.

It’s strange to think of the Moon with volcanic activity viewable from Earth. I wonder what effect visible lunar volcanoes would have had on thinkers like Aristotle, if lunar volcanic activity had occurred during recorded history, rather than ending one billion years ago or so.

We know that events like eclipses and comets caused great confusion and sometimes upheaval in ancient civilizations. Would lunar volcanoes have had the same effect?

Posted on by Evan Gough

Most ‘Outrageous’ Luminous Galaxies Ever Observed

An artist's conception of an extremely luminous infrared galaxy similar to the ones reported in this paper. Image credit: NASA/JPL-Caltech.
An artist's conception of an extremely luminous infrared galaxy similar to the ones reported in this paper. Image credit: NASA/JPL-Caltech.

Astronomers might be running out of words when it comes to describing the brightness of objects in the Universe.

Luminous, Super-Luminous, Ultra-Luminous, Hyper-Luminous. Those words have been used to describe the brightest objects we’ve found in the cosmos. But now astronomers at the University of Massachusetts Amherst have found galaxies so bright that new adjectives are needed. Kevin Harrington, student and lead author of the study describing these galaxies, says, “We’ve taken to calling them ‘outrageously luminous’ among ourselves, because there is no scientific term to apply.”

The terms “ultra-luminous” and “hyper-luminous” have specific meanings in astronomy. An infrared galaxy is called “ultra-luminous” when it has a rating of about 1 trillion solar luminosities. At 10 trillion solar luminosities, the term “hyper-luminous” is used. For objects greater than that, at around 100 trillion solar luminosities, “we don’t even have a name,” says Harrington.

The size and brightness of these 8 galaxies is astonishing, and their existence comes as a surprise. Professor Min Yun, who leads the team, says, “The galaxies we found were not predicted by theory to exist; they’re too big and too bright, so no one really looked for them before.” These newly discovered galaxies are thought to be about 10 billion years old, meaning they were formed about 4 billion years after the Big Bang. Their discovery will help astronomers understand the early Universe better.

“Knowing that they really do exist and how much they have grown in the first 4 billion years since the Big Bang helps us estimate how much material was there for them to work with. Their existence teaches us about the process of collecting matter and of galaxy formation. They suggest that this process is more complex than many people thought,” said Yun.

Gravitational lensing plays a role in all this though. The galaxies are not as large as they appear from Earth. As their light passes by massive objects on its way to Earth, their light is magnified. This makes them look 10 times brighter than they really are. But event taking gravitational lensing into account, these are still impressive objects.

But it’s not just the brightness of these objects that are significant. Gravitational lensing of a galaxy by another galaxy is rare. Finding 8 of them is unheard of, and could be “another potentially important discovery,” says Yun. The paper highlights these galaxies as being among the most interesting objects for further study “because the magnifying property of lensing allows us to probe physical details of the intense star formation activities at sub-kpc scale…”

The team’s analysis also shows that the extreme brightness of these galaxies is caused solely by star formation.“The Milky Way produces a few solar masses of stars per year, and these objects look like they forming one star every hour,” Yun says. Harrington adds, “We still don’t know how many tens to hundreds of solar masses of gas can be converted into stars so efficiently in these objects, and studying these objects might help us to find out.”

It took a tag team of telescopes to discover and confirm these outrageously luminous galaxies. The team of astronomers, led by Professor Min Yun, used the 50 meter diameter Large Millimeter Telescope for this work. It sits atop an extinct volcano in Mexico, the 15,000 foot Sierra Negra. They also relied on the Herschel Observatory, and the Planck Surveyor.

Posted on by Evan Gough

Solar Storms Ignite Aurora On Jupiter

Composite images from the Chandra X-Ray Observatory and the Hubble Space Telescope show the hyper-energetic x-ray auroras at Jupiter. The image on the left is of the auroras when the coronal mass ejection reached Jupiter, the image on the right is when the auroras subsided. The auroras were triggered by a coronal mass ejection from the Sun that reached the planet in 2011. Image: X-ray: NASA/CXC/UCL/W.Dunn et al, Optical: NASA/STScI
Composite images from the Chandra X-Ray Observatory and the Hubble Space Telescope show the hyper-energetic x-ray auroras at Jupiter. The image on the left is of the auroras when the coronal mass ejection reached Jupiter, the image on the right is when the auroras subsided. The auroras were triggered by a coronal mass ejection from the Sun that reached the planet in 2011. Image: X-ray: NASA/CXC/UCL/W.Dunn et al, Optical: NASA/STScI

The Earthly Northern Lights are beautiful and astounding, but when it comes to planetary light shows, what happened at Jupiter in 2011 might take the cake. In 2011, a coronal mass ejection (CME) struck Jupiter, producing x-ray auroras 8 times brighter than normal, and hundreds of times more energetic than Earth’s auroras. A paper in the March 22nd, 2016 issue of the Journal of Geophysical Research gave the details.

The Sun emits a ceaseless stream of energetic particles called the solar wind. Sometimes, the Sun ramps up its output, and what is called a coronal mass ejection occurs. A coronal mass ejection is a massive burst of matter and electromagnetic radiation. Though they’re slow compared to other phenomena arising from the Sun, such as solar flares, CMEs are extremely powerful.

When the CME in 2011 reached Jupiter, NASA’s Chandra X-Ray Observatory was watching, the first time that Jupiter’s X-ray auroras were monitored at the same time that a CME arrived. Along with some very interesting images of the event, the team behind the study learned other things. The CME that struck Jupiter actually compressed that planet’s magnetosphere. It forced the boundary between the solar wind and Jupiter’s magnetic field in towards the planet by more than 1.6 million kilometers (1 million miles.)

The scientists behind this study used the data from this event to not only pinpoint the source of the x-rays, but also to identify areas for follow-up investigation. They’ll be using not only Chandra, but also the European Space Agency’s XMM Newton observatory to collect data on Jupiter’s magnetic field, magnetosphere, and aurora.

NASA’s Juno spacecraft will reach Jupiter this summer. One of its primary missions is to map Jupiter’s magnetic fields, and to study the magnetosphere and auroras. Juno’s results will be fascinating to anyone interested in Jupiter’s auroras.

Here at Universe Today we’ve written about Jupiter’s aurora’s here, coronal mass ejections here, and the Juno mission here.

Posted on by Evan Gough

High Albedo Points To Huge Collision Forming Plutonian System

Data from New Horizons supports the theory that Pluto's 4 small moons were formed as a result of a collision. Image by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Data from New Horizons supports the theory that Pluto's 4 small moons were formed as a result of a collision. Image by NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

The high albedo (reflectivity) of some of Pluto’s moons supports the theory that those moons were formed as a result of a collision, rather than being Kuiper Belt Objects (KBOs) that wandered too close and were captured by Pluto’s gravity. Data supporting the collision theory came from NASA’s New Horizons spacecraft as it flew by Pluto in July 2015.

The Pluto system is a complex one. Pluto has 5 moons: Charon, Styx, Nix, Kerberos, and Hydra. Charon is the only moon that is tidally locked with Pluto, and the two are sometimes called a double dwarf planet. The system’s barycenter lies between Pluto and Charon, though much closer to Pluto. The objects in the system move in near-circular orbits, rather than ellipses.

Pluto and Charon were thought to have formed the same way the other planets formed in the Solar System; by coalescing out of a ring of debris left over after the Sun formed. Then, it was thought, the other Plutonian moons were captured from the Kuiper Belt. Pluto resides in the Kuiper Belt, so this made sense. Some of the other moons in our Solar System, like Neptune’s Triton and Saturn’s Phoebe, are also thought to be captured Kuiper Belt Objects (KBOs).

A competing theory for the formation of the Pluto system is the collision theory. This theory states that Pluto and Charon did indeed coalesce out of the ring of debris around the Sun, and that Charon was itself a dwarf planet. But a collision occurred after that, about 4 or 4.5 billion years ago, between Pluto and an object about the same size as Pluto.

This collision left Pluto and Charon in their binary state, but created a circumbinary disk of debris out of which the other 4 moons formed. There are competing versions of these theories, one of which suggests that all of Pluto’s 5 moons were formed by this collision, and none coalesced out of the circumstellar disk of debris that the other planets were formed from.

New Horizons has delivered measurements and data showing that the albedo of Pluto’s 4 smallest moons is much too high for captured KBOs. Their surface reflectivity is highly suggestive of a water-ice composition. Measured KBOs have a geometric albedo of less than .20, while Styx, Nix, Hydra, and Kerberos have values of .40, .57, .56, and .45 respectively. This points to the idea that the object that collided with Pluto 4 to 4.5 billion years ago had at least some icy surface layers.

Pluto’s 4 small moons, Styx, Nix, Kerberos, and Hydra, are all non-spheroidal. This also points to their origins as conglomerated objects which formed from a collision-induced debris disk, rather than as captured Kuiper Belt objects.

These results were published in the journal Science, on March 18th, 2016. They were gathered using the Long-Range Reconnaissance Imager (LORRI), and the Multispectral Visible Imaging Camera (MVIC) instruments on board New Horizons.

Half of the data from New Horizons’ visit to Pluto is yet to arrive, including data from the Linear Etalon Imaging Spectral Array (LEISA). Scientists are hopeful that this data, and all the existing data which together will take years to analyze, will answer some of the questions surrounding the formation of the Pluto system.

Posted on by Evan Gough

Ancient Pluto May Have Had Lakes And Rivers Of Nitrogen

The New Horizons team used "principal component analysis" to get this false-color image that highlights the different regions of Pluto. Image: NASA/New Horizons/JHAPL
The New Horizons team used "principal component analysis" to get this false-color image that highlights the different regions of Pluto. Image: NASA/New Horizons/JHAPL

The New Horizons probe revealed the surface features of Pluto in rich detail when it reached the dwarf planet in July 2015. Some of the features look like snapshots of rivers and lakes that are locked firmly in place by Pluto’s frigid temperatures. But now scientists studying the data coming back from New Horizons think that those frozen lakes and rivers could once have been liquid nitrogen.

Pluto has turned out be a surprisingly active place. New Horizons has shown us what might be clouds in Pluto’s atmosphere, mountains that might be ice volcanoes, and cliffs made of methane ice that melt away into the plains. If there were oceans and rivers of liquid nitrogen on the surface of Pluto, that would fit in with our evolving understanding of Pluto as a much more active planet than we thought.

Richard Binzel, a New Horizons team member from MIT, thinks that lakes of liquid nitrogen could have existed some 800 or 900 million years ago. It all stems from Pluto’s axial tilt, which at 120 degrees is much more pronounced than Earth’s relatively mild 23 degree tilt. And computer modelling suggests that this tilt could have even been more extreme many millions of years ago.

The result of this extreme tilt is that much more of Pluto’s surface would have been exposed to sunlight. That may have warmed Pluto enough to allow liquid nitrogen to flow over the planet’s surface. These kinds of changes to a planet’s axial tilt, (and precession and eccentricity) affect a planet’s climate in what are called Milankovitch cycles. The same cycles are thought to have a similar effect on Earth’s climate, though not as extreme as on Pluto.

According to Binzel, Pluto could be somewhere in between its temperature extremes, meaning that if Pluto will ever be warm enough for liquid nitrogen again, it could be hundreds of millions of years from now. “Right now, Pluto is between two extreme climate states,” Binzel says.

Alan Stern is a planetary scientist at the Southwest Research Institute, and New Horizons’ Principal Investigator. He thinks that these long-cycle climate changes could have a very pronounced effect on Pluto, which has a nitrogen-rich atmosphere. In ancient times, Pluto’s atmosphere could have been more dense than Mars’. “This opens up the possibility that liquid nitrogen may have once or even many times flowed on Pluto’s surface,” he said.

More data from New Horizons is still on its way. About half is yet to arrive. That data, and further analysis, might discredit the fledgling idea that Pluto had and will have again lakes of liquid nitrogen. “We are just beginning to understand the long-term climate of Pluto,” said Binzel.

This week is the 47th Lunar and Planetary Science Conference (LPSC) in Houston. Members of the New Horizons team will be presenting almost 40 reports on Pluto and its system of moons at this conference. Stern’s lecture, titled “The Exploration of Pluto,” will be archived online at http://livestream.com/viewnow/LPSC2016.

Posted on by Evan Gough

Kepler Catches Early Flash Of An Exploding Star

“Life exists because of supernovae,” said Steve Howell, project scientist for NASA’s Kepler and K2 missions at NASA’s Ames Research Center. “All heavy elements in the universe come from supernova explosions. For example, all the silver, nickel, and copper in the earth and even in our bodies came from the explosive death throes of stars.”

So a glimpse of a supernova explosion is of intense interest to astronomers. It’s a chance to study the creation and dispersal of the life-enabling elements themselves. A greater understanding of supernovae will lead to a greater understanding of the origins of life.

Stars are balancing acts. They are a struggle between the pressure to expand, created by the fusion in the star, and the gravitational urge to collapse, caused by their own enormous mass. When the core of a star runs out of fuel, the star collapses in on itself. Then there is a massive explosion, which we call a supernova. And only very large stars can become supernovae.

The brilliant flashes that accompany supernovae are called shock breakouts. These events last only about 20 minutes, an infinitesimal amount of time for an object that can shine for billions of years. But when Kepler captured two of these events in 2011, it was more than just luck.

Peter Garnavich is an astrophysics professor at the University of Notre Dame. He led an international team that analyzed the light from 500 galaxies, captured every 30 minutes over a period of 3 years by Kepler. They searched about 50 trillion stars, trying to catch one as it died as a supernova. Only a fraction of stars are large enough to explode as supernovae, so the team had their work cut out for them.

“In order to see something that happens on timescales of minutes, like a shock breakout, you want to have a camera continuously monitoring the sky,” said Garnavich. “You don’t know when a supernova is going to go off, and Kepler’s vigilance allowed us to be a witness as the explosion began.”

An artist's concept of a shock breakout. Image: NASA Ames/STScl/G. Bacon
An artist’s concept of a shock breakout. Image: NASA Ames/STScl/G. Bacon

In 2011 Kepler caught two gigantic stars as they died their supernova death. Called KSN 2011a, and KSN 2011d, the two red super-giants were 300 times and 500 times the size of our Sun respectively. 2011a was 700 million light years from Earth, and 2011d was 1.2 billion light years away.

The intriguing part of the two supernovae is the difference between them; one had a visible shock breakout and one did not. This was puzzling, since in other respects, both supernovae behaved much like theory predicted they would. The team thinks that the smaller of the two, KSN 2011a, may have been surrounded by enough gas to mask the shock breakout.

The Kepler spacecraft is well-known for searching for and discovering extrasolar planets. But when some components on board Kepler failed in 2013, the mission was re-cast as the K2 Mission. “While Kepler cracked the door open on observing the development of these spectacular events, K2 will push it wide open, observing dozens more supernovae,” said Tom Barclay, senior research scientist and director of the Kepler and K2 guest observer office at Ames. “These results are a tantalizing preamble to what’s to come from K2!”

(For a brilliant and detailed look at the life-cycle of stars, I recommend “The Life and Death of Stars” by Kenneth R. Lang.)