New data from the Voyager 1 probe, more than 11 billion miles away from the sun, indicate that it has entered interstellar space after 35 years of travel. Image via NASA/JPL

Update: Since the press release announcing Voyager 1′s exiting the solar system, NASA has clarified that the final indicator of this event—a change in the direction of the magnetic field surrounding the craft—has still not been observed. As was first observed in December 2012, Voyager 1 is in a new outermost region of the solar system called “the magnetic highway,” not true interstellar space. This post has been edited to reflect the clarification.

Since the dawn of the Space Age, our manned missions and unmanned probes have reached the Moon, asteroids and other planets. But only now do we have confirmation that a human-made object has reached a new milestone: The Voyager 1 space probe is at the furthermost edge of the solar system.

According to a paper recently accepted for publication by the journal Geophysical Research Letters, data transmitted by probe—which is now more than 11 billion miles away from the Sun—reveal that it has exited the heliosphere. The heliosphere (also called the heliosheath) is the region of space influenced by the solar wind and is commonly accepted as the outer border of the solar system. Thirty-five years, 6 months and 15 days after its launch, the spacecraft will soon enter the second phase of its mission—studying the interstellar medium that exists between our galaxy’s star systems.

Bill Webber of New Mexico State and F.B. McDonald of the University of Maryland (who has passed away since the paper was written) came to the conclusion after analyzing radiation data transmitted by Voyager 1 last August 25. The probe’s sensors detected that the levels of radiation from cosmic rays that had come from the Sun dropped to less than 1 percent of what they’d been previously, while radiation from galactic cosmic rays (which originate from beyond the solar system) doubled in intensity.

Although there is no exact boundary that defines the edge of the solar system, the point at which the Sun’s cosmic rays and galactic cosmic rays meet indicates the edge of the region dominated by our Sun’s solar wind, and thus the outside border of our star’s system. Webber says that the sudden change in radiation indicates Voyager 1 passed this point.

“Within just a few days, the heliospheric intensity of trapped radiation decreased, and the cosmic ray intensity went up as you would expect if it exited the heliosphere,” he said in a press release issued by the American Geophysical Union today. He also noted that it’s possible the probe hasn’t reached true interstellar space, but rather a separate, not-yet-understood region that lies in between our solar system and the interstellar medium.

This image from 2009 shows Voyager 1 at the edge of the heliosheath. But new data indicate Voyager 1 has passed the heliopause and entered the interstellar medium. Image via NASA/JPL

Since its launch in 1977, the spacecraft has conducted a grand tour of the solar system, passing by and photographing Jupiter and Saturn and providing us with some of the first-ever close-ups of the gas giants. Voyager 2, a twin probe, visited Jupiter, Saturn, Uranus and Neptune, and is still firmly within the solar system for now, 9.4 billion miles away from the Sun.

In 2005, Voyager 1 entered the heliosheath (the region in which the solar wind begins to slow down due to encountering the interstellar medium), and last October, researchers reported that it may have left the heliosphere altogether. Soon afterward, though, scientists cautioned that it may not have exited the heliosphere’s outer boundary, because a shift in the direction of the magnetic field had not yet been detected.

Despite the announcement alongside the new paper, this may still be the case—Voyager 1 may have finally exited the heliosphere, but not yet entered interstellar space per se. According to NASA, “A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed.” Thus, the probe is in an unexpected region in between the heliosphere and interstellar space, previously referred to as a magnetic highway.

Either way, though, it’s still in the starting stages of its journey, set to spend millennia—yes, millenia—traveling through the interstellar medium, though it will probably not be able to record or send back data after around 2025.

After an estimated 40,000 years, it will come relatively close (within a light year) to another star—and at that point, could serve as something of a time capsule. The Voyager 1 carries a Golden Record, designed to present a virtual snapshot of humankind to other life forms, contains everything from images of DNA and the Taj Mahal to recordings of whale sounds and Chuck Berry’s “Johnny B. Goode.”

As Timothy Ferris wrote in Smithsonian last May when he reflected on the 35th anniversary of the Voyager mission, “The Voyagers will wander forever among the stars, mute as ghost ships but with stories to tell…Whether they will ever be found, or by whom, is utterly unknown.”

Mars, photo via Pixabay

Roughly 3.5 billion years ago, Mars began to shift from a wetter, warmer climate to the dry and cold planet we see today. This period of geologic change, known as the Hesperian age, was a turbulent time. The red planet saw widespread volcanic eruptions and catastrophic flooding as melted ice rushed into wide craters, forming lakes. These natural disasters carved a network of basins into its surface called outflow channels, eroding the terrain and reshaping the landscape of the planet. The exact end of this geologic period in Mars’ history is unknown, but scientists give a rough estimate of 3 billion years ago.

Later, many of these outflow channels became covered with lava, burying evidence of Mars’ geologic history. But now, a new map of the planet’s subsurface shows for the first time what one of these buried channels looks like in three dimensions. The findings, published today in the journal Science, reconstruct the Marte Vallis, the largest of the youngest channels on Mars. Marte Vallis is located in the Elysium Planitia region, an expanse of plains along the equator and the youngest volcanic region on the planet.

To create the 3D map,  the researchers used data from Shallow Radar, a device that probes for liquid or frozen water underneath Mars’ crust. Known as SHARAD, the technology is on board NASA’s Mars Reconnaissance Orbiter spacecraft, which is currently circling the planet to study its climate. SHARAD’s orbital sounding radar works in much the same way as medical imaging scans. It sends signals to the surface, some of which automatically bounce back to the spacecraft. The signals that don’t readily bounce back can penetrate Mars’ crust and register buried structures before returning to the device. The data appears in two-dimensional cross sections, which are then pieced together to build the 3D representation. In this manner, a deeply grooved set of channels was revealed.

3D visualization of the buried Marte Vallis channels underneath the surface of Mars. Image via Smithsonian Institution/NASA/JPL-Caltech/Sapienza University of Rome/MOLA Team/USGS

The system of channels, which is somewhere between 10 million to half a billion years old, spans 60 miles in width and stretches for more than 600 miles in length. From what can be seen of Marte Vallis from the surface, the channels are similar in structure to more ancient channel systems traced to the Hesperian, but the lava that had obscured many of their features made it difficult for researchers to make accurate estimates about its depth.

The new data reveals that the scale of erosion for Marte Vallis had indeed been underestimated: the 25-mile-wide main channel is at least twice as deep than earlier approximations indicated. The map shows multiple perched channels which feed into the deeper and wider main channel. These channels once lay along a series of four islands, which floods eroded into teardrop-shaped hills.

The researchers found that the geometry of the features are similar to those of the planet’s oldest channels, which are less obscured by lava, making them easier to study. This also suggests that the Marte Vallis could have been carved entirely by water, says lead study author Gareth Morgan, a geologist at the National Air and Space Museum’s Center for Earth and Planetary Studies. In fact, most Mars scientists accept that outflow channels on Mars were carved by water. Lava also carves out tunnels through thermal erosion heating up the terrain, but Morgan says that this process is implausible for the scale of erosion at the Marte Valle channels. The speed of rushing water is also more efficient at erosion that the flow of lava, which can get stuck on rock, Morgan says. In addition, lava creates tunnels that aren’t as wide—typically only several miles across—so collapsed tunnels couldn’t account for the broad size of the channels.

Using the map, researchers were also able to pinpoint the source of the floodwater: a now buried portion of the Cerberus Fossae fracture, a series of fissures in the planet’s surface. The researchers posit that water from a reservoir deep below Mars’ surface was released by nearby tectonic or volcanic activity, and it worked quickly to form the channels. These channels would have been a short-lived affair,” Morgan says. “The fracture would have connected this groundwater to the surface. After a short duration of weeks or months, the source would have been exhausted.”

But why was water in that reservoir during a time when the rest of Mars is believed to have been dry? Water, the authors believe, could have collected in aquifers below the surface during the Hesperian. This water hypothetically could have remained stable in liquid form long after the Hesperian ended. Morgan feels that the 3D map could provide more evidence to support this hypothesis, showing that Mars was wet place in the more recent—as opposed to far ancient—past.

More than 20 similar outflow channels are spread out on the surface of the planet, extending hundreds of miles in length. The most prominent are located in the Chryse Planitia, a circular volcanic plain in the northern hemisphere of Mars. The largest, the Kasei Valles, runs for 1,500 miles along the plain.

Cataclysmic floods like the ones that shaped Mars’ channels aren’t unique to the red planet. Approximately 14,000 years ago, the largest known flood on Earth sprang from Lake Missoula, a prehistoric body of water that existed at the end of the last Ice Age in present-day Montana. The waters eroded part of the landscape of Washington state, forming the Channeled Scablands, a terrain that resembles Martian outflow channels. Marte Vallis’ main channel is estimated to be between 226 and 371 feet deep, a depth that’s comparable to the Channeled Scablands.

So if Mars’ expansive outflow channels were formed by gushing water, the question remains: Where did it all ago?

Some of it vaporized, drifted to the planet’s poles, and precipitated as ice on polar caps, Morgan says. Similar to the ones we have on Earth, the polar ends on the Red Planet are covered in miles-thick layers of ice. The water also could have pooled into shallow areas below the surface, where it also froze—in 2008, NASA’s Phoenix mission confirmed that ice exists in the porous soil that makes up much of the planet’s surface.

Another possibility, Morgan says, is that the ancient water again escaped deep underground, forming a large reservoir that awaits its chance to flood again.

Galaxy M106′s spiral arms. Image via NASA, ESA, the Hubble Heritage Team (STScI/AURA), and R. Gendler (for the Hubble Heritage Team) and J. GaBany

Space added several stunning new images to its photo album this week, including the one above of spiral galaxy M106, located 23.5 million light-years away in the constellation Canes Venatici, Notice something?

The image, released yesterday, actually contains two spirals overlain on each other. One is the cloudy, blue-white spiral with a yellow core. The core itself is a composite of images take by the Hubble Space Telescope‘s Advanced Camera for Surveys, Wide Field Camera 3, and Wide Field Planetary Camera 2 detectors. Spiraling outward, the cloudy arms also come from Hubble, but were colorized with ground-based images captured from relatively small telescopes (12.5-inch and 20-inch) as they imaged from dark, remote sites in New Mexico. The telescopes, owned by photo-astronomers Robert Gendler and R. Jay GaBany, helped these astronomy enthusiasts fill in gaps left by Hubble’s cameras. The images were meticulously assembled into a mosaic by Gendler, a physician by training, to form the base spiral of the photo illustration above.

But what about the second spiral? Emanating at odd angles is a glowing red swirl, known as the “anomalous arms” of M106, These arms, captured by Hubble imagery and GaBany’s telescope, are enormous streamers of irradiated hydrogen gas molecules which glow red when seen through special filters. This begs the question–what’s cooking the hydrogen?

The answer is…a black hole! As astronomer Phil Plait blogs in Slate, “Every big galaxy has a supermassive black hole in its core. The Milky Way has one, and it has about 4 million times the mass of the Sun. The black hole at M106’s heart is about 30 million times the mass of our Sun. Besides being heftier it’s also actively feeding, gobbling down material swirling around it (our own galaxy’s black hole is quiescent; that is, not eating anything at the moment).”

While this photo shows stars at the brink of death within M106, another photo released yesterday shows the environment of stars at their birth:

The Orion nebula, newly imaged by NASA’s Wide-field Infrared Survey Explorer (WISE). Image via NASA/JPL-Caltech/UCLA

Tinged an eerie green–like smoke from a witch’s brew–the new image from NASA’s Wide-field Infrared Survey Explorer (WISE) was taken after zooming in on bright dot in the “sword” of the constellation Orion. Visible to the naked eye as a single fuzzy star (also known as M42), the dot is actually a cluster of stars, surrounded by the Orion nebula. Here, stars are born.

The image captures the infrared nimbus formed as newborn stars are compressed from vast clouds of gas and heat the wisps that remain. White regions are the hottest part of these stars’ first dust bath, while greens and reds show lukewarm dust. Carving holes through the dust are massive stars–newly formed–such as the one seen at the picture’s center.

The Orion nebula is a site of star formation close to the Earth, giving scientists the opportunity to study its characteristics and hypothesize on how our Sun was born five billion years ago, perhaps from a similar cloud of dust. The white orbs seen here are less than 10 million years old.

The images of the death and birth of stars–both hauntingly beautiful–showcase the evolving nature of space. Mirrored by our own cycles of life and death, the pictures help to link our daily grind with the vastness beyond Earth.

Super-Earth exoplanets may actually be severely uninhabitable, new research suggests. Artist’s rendition from NASA

The discovery of planets beyond our solar system, along with recent efforts to catalog them, has fueled the search for rocky planets similar to Earth that may have conditions suitable for life. For the past 20 years, many scientists have focused on locating “super-Earths“–planets heavier than Earth but with masses quite a bit below that of Neptune or Uranus–in the so-called “habitable zone” of their stars. Within this zone, it is theoretically possible for a planet with the right atmospheric pressures to maintain liquid water on its surface.

In early January, astronomers working on NASA’s Kepler Mission announced the discovery of KOI 172.02 (KOI for Kepler Object of Interest), an exoplanet candidate that is about 1.5 times the radius of Earth, orbiting in the habitable zone of a G-type star slightly cooler than our Sun. If confirmed, the planet, which orbits its sun every 242 days, is “our first habitable-zone super Earth around a sun-type star,” astronomer Natalie Batalha, a Kepler co-investigator at NASA’s Ames Research Center, told Space.com. Batalha and colleagues hail KOI 172.02 as the exoplanet most like Earth, and thus is a prime candidate for hosting life, they expect.

But don’t get too excited–new research suggests that most of these super-Earths may never support life because they are permanently encased in hydrogen-rich atmospheres. The findings, released yesterday in the Monthly Notices of the Royal Astronomical Society, show that these super-Earths may actually be mini-Neptunes. Further, these exoplanets will likely never evolve to look like Mercury, Venus, Earth, or Mars–the rocky planets of our inner solar system.

Led by Helmut Lammer of the Austrian Academy of Sciences’s Space Research Institute (IWF), researchers examined how radiation from the stars Kepler-11, Gliese 1214 and 55 Cancri would effect on the upper atmospheres of the super-Earths orbiting too close to their host stars to be in the habitable zone. These super-Earths have sizes and masses that indicate they have rocky interiors surrounded by hydrogen-rich atmospheres–atmospheres that were likely captured early in the planet’s history from the clouds of dust and gas that formed the systems’ nebulae.

Using a model that simulates the dynamic properties of planetary atmospheres, the researchers showed how the extreme ultraviolet light from the host stars heat up the exoplanets’ atmospheres, and as a result, the atmospheres expand several times the radius of each planet, allowing gases to escape. But not fast enough.

“Our results indicate that, although material in the atmosphere of these planets escapes at a high rate, unlike lower mass Earth-like planets many of these super-Earths may not get rid of their nebula-captured hydrogen-rich atmospheres,” Lammer said in a statement.

A rough concept of the newly modeled super-Earths compared to the actual Earth. Super-Earths are more massive than Earth, but are generally less than 10 times Earth’s mass. By contrast, Neptune is about 15 times Earth’s mass. Image from H. Lammar

If their model is correct, its implications spell doom for life on exoplanets further out, in the ‘habitable zone.’ Although temperatures and pressures would allow liquid water to exist, gravity and an inability for their suns to blow off their atmospheres would forever preserve their thick hydrogen-rich atmospheres. Thus, they probably could not sustain life.

Scientists may have to wait until 2017–after the European Space Agency launches the Characterising Exoplanets Satellite (CHEOPS)–before they can learn whether these findings stand the test of time. CHEOPS. Until then, the search for exoplanets with conditions ripe for life has gotten a lot harder.

A graphic data readout of the a collision of two protons, briefly producing a Higgs Boson, from the Large Hadron Collider. Image via CERN

The year 2012 was a major one for science. We saw scientists develop a new type of drug to combat HIV, figure out how to store digital data in DNA—fitting an astonishing 700 terabytes of information into a single gram of it—and even invent a coating for the inside of condiment bottles that could eliminate our stuck-ketchup-headaches once and for all (though, admittedly, this one is a little less groundbreaking than the others). Yet a few milestones in particular—discoveries, technological feats, realizations, and inventions—stand out:

1. The Higgs Boson: The landmark discovery by the European Organisation for Nuclear Research (CERN) of the once-mythical particle might be the most significant scientific discovery of our lifetimes, but it’s also one of the most surprising. Stephen Hawking, the Einstein of our time, famously bet Michigan physicist Gordon Kane $100 that it would never be found.

In an interview with The Atlantic, physicist Lawrence Krauss explained why so many experts had agreed with Hawking, arguing that the existence of the Higgs—a particle (and associated field) that makes certain types of elementary particles behave as though they had mass—was just too convenient, as it was originally posited simply to explain away an apparent difficulty in an otherwise appealing theory in theoretical physics.

The theory seeks to unite all physical forces under the same set of rules. But how can electromagnetic forces–governed by massless photons–fit under the same theoretical umbrella as the weak force, which is governed by bosons with discernible mass that control radioactive decay? Efforts to answer this conundrum gave birth to  the Higgs boson. Krauss noted,”It seemed too easy…It seemed to me that introducing an invisible field to explain stuff is more like religion than science…Great, I invented invisible hobgoblins to make things right.”

Incredibly, in this case, it turned out the hobgoblins were real.

An artist’s rendering of the theorized Earth-like planet, potentially capable of containing liquid water. Image via University of Hertfordshire/J. Pinfield

2. Earth-Like Planets: 2012 featured a ton of exoplanet discoveries, but the sighting of HD 40307g was without a doubt the most unexpected and exciting.  The planet, bigger than earth but not so large as to be a gas giant, seems to orbit in its sun’s “goldilocks zone” (not too hot and not too cold), making it potentially capable of hosting liquid water, considered a prerequisite for life as we know it.

Even better, it’s just 42 light-years away: distant by human standards, but fairly close by compared many of the astronomical objects, making future projects to observe the planet much more feasible.

A composite image of self-portraits taken by Curiosity on Mars. Image via NASA/JPL-Caltech/MSSS

3. Curiosity Reaches Mars: Okay, the mission itself wasn’t too surprising—it’s been in the works since 2004—but what was so astonishing was the sudden surge of public interest in the rover and in space exploration as a whole. For decades following the manned Apollo missions of the 1960s and 70s, general enthusiasm for space science had slowly ebbed. After Curiosity’s successful landing, though, it surged. Among other things, video of NASA engineers celebrating the feat went viral and the official Curiosity twitter account garnered some 1.2 million followers.

People are so interested in Curiosity‘s exploits, in fact, that even an engineer’s throwaway line about “a discovery for the history books” pumped up expectations so much that we were bound to be disappointed by the actual finding: that early Martian soil samples seem to be representative of what we know of the planet as a whole, and that its chemistry is complex enough to have potentially once supported life. Bigger news might come over the next few years, but as project scientist John Grotzinger said, “Curiosity’s middle name is patience.”

For many Americans, Superstorm Sandy drove home the idea that climate change is real. Image via NASA

4. Climate Change Is Even Worse Than We Thought: After decades of warnings from scientists that our greenhouse gas emissions will soon wreak havoc with the climate, we’re now starting to see the consequences—and they sure aren’t pretty. As a whole, experts are saying that the even the most frightening climate scenarios have proved to be too conservative in their analysis of how rising carbon dioxide concentrations will alter precipitation patterns, drive ocean acidification, lead to more powerful storms and, in general, make most parts of the planet grow warmer.

One silver lining might be that the public is now starting to acknowledge climate change as a present-day problem, rather than a hypothetical trend that could take effect in the future. Sadly, this has come only after record-breaking heat waves, droughts and the tragic impacts of Hurricane Sandy. Although the most recent international climate talks in Doha accomplished little, there are hopes that this shift in opinion could lead to a long-awaited change in policy sometime soon.

A digital rendering at the atomic level of a new type of water desalinization method developed at MIT, which uses a one-atom-thick sheet of graphene (blue) to filter impurities (green and purple ) from water molecules (red and white). Image via David Cohen-Tanugi

5. A New Way to Desalinate Seawater: With world populations expected to keep growing and potable water projected to grow more scarce over the coming century, a practical and cheap means of desalinating sea water is one of materials science’s holy grails. In July, MIT researchers announced the development of a new method of desalinization using one-atom-thick sheets of graphene, a pure carbon substance. Their method could be far cheaper and less energy-intensive than existing systems—potentially providing a way to solve many of the world’s water problems once and for all.

An artist’s conception of the massive collision that would have produced the moon roughly 4.5 billion years ago. Image via NASA/JPL-Caltech

It’s hard to take a look at a full moon, so different than any other object in the night sky, and not wonder how it formed. Scientists have proposed several different mechanisms to explain the formation of the moon—that it came from material flung off of the Earth due to centrifugal force, that it was already formed when captured by the Earth’s gravity and that the Earth and moon both formed together during the birth of the Solar System.

Starting in the 1970s, though, experts began to suspect a rather more dramatic creation story: that the moon formed as the result of a massive collision between a Mars-sized protoplanet and a young Earth, some 4.5 billion years ago. In this theory, roughly 30 million years after the Solar System began to form, the smaller protoplanet (often called Theia) would have slammed into the Earth at nearly 10,000 miles per hour, generating an enormous explosion. Much of Theia’s denser elements, such as its iron, would have sunken into Earth’s core, whereas lighter mantle material from both Earth and Theia would have been vaporized and ejected into orbit, soon coalescing into what we now know as the moon, held in place by Earth’s gravity.

We’ve already found several indirect pieces of evidence for this idea: moon rocks collected by Apollo show oxygen isotope ratios similar to those on earth, and the moon’s movement and rotation indicate that it has an unusually small iron core, as compared with other objects in the Solar System. We’ve even observed belts of dust and gas around distant stars that likely formed in similar collisions between rocky bodies.

Now, scientists from Washington University in St. Louis and elsewhere, reporting today in Nature, have uncovered an entirely new type of proof for this theory of moon formation. The researchers closely examined 20 different lunar rock samples collected from distant locations on the moon during the Apollo missions and discovered the first direct physical evidence of the type of massive vaporization event that would have accompanied the hypothesized impact.

A cross-polarized transmitted-light image of a moon rock, in which scientists found an excess of heavier zinc isotopes. Image by J. Day

In scrutinizing the lunar rocks, the geochemists found a molecular signature of vaporization in the type of zinc isotopes embedded in the samples. Specifically, they detected a slight irregularity in the amount of heavier zinc isotopes, as compared to lighter ones.

The only realistic explanation for this type of distribution, they say, is a vaporization event. If Theia collided with the Earth billions of years ago, the zinc isotopes in the resulting vaporization cloud would have condensed into the rapidly-forming moon in a very particular way.

“When a rock is melted and then evaporated, the light isotopes enter the vapor phase faster than the heavy isotopes,” says Washington University geochemisty Frédéric Moynier, the lead author of the paper. “You end up with a vapor enriched in the light isotopes and a solid residue enriched in the heavier isotopes. If you lose the vapor, the residue will be enriched in the heavy isotopes compared to the starting material.”

In other words, the vapor that would have escaped out to space would be disproportionately rich in the light zinc isotopes, and the rock left behind would have an excess of heavy ones. That’s exactly what the team found in the lunar rocks they examined. To strengthen the study, they also looked at rocks from Mars and Earth, comparing the isotope distribution in each sample—and the excess of heavy isotopes in the lunar rocks was ten times greater than that of the others.

Of course, the study isn’t definitive proof that the moon formed from a collision, but unlike with the previous circumstantial evidence, it’s difficult to come up with an alternate theory that would explain the signature found in the rocks. We can’t go back 4.5 billion years to know for sure, but we’re closer than ever to knowing just how our planet ended up with its moon.

The newly discovered Comet ISON is at the crosshairs of this image, taken at the RAS Observatory near Mayhill, New Mexico. Image via E. Guido/G. Sostero/N. Howes

Last Friday, a pair of Russian astronomers, Artyom Novichonok and Vitaly Nevski, were poring over images taken by a telescope at the International Scientific Optical Network (ISON) in Kislovodsk when they spotted something unusual. In the constellation of Cancer was a point of light, barely visible, that didn’t correspond with any known star or other astronomical body.

Their discovery—a new comet, officially named C/2012 S1 (ISON)—was made public on Monday, and has since made waves in the astronomical community and across the internet.

As of now, Comet ISON, as it’s commonly being called, is roughly 625 million miles away from us and is 100,000 times fainter than the dimmest star that can be seen with the naked eye—it’s only visible using professional-grade telescopes. But as it proceeds through its orbit and reaches its perihelion, its closest point to the sun (a distance of 800,000 miles) on November 28th, 2013, it could be bright enough to be visible in full daylight in the Northern Hemisphere, perhaps even as bright as a full moon.

With current information, though, there’s no way of knowing for sure, and experts disagree on what exactly we’ll see. “Comet C/2012 S1 (ISON) probably will become the brightest comet anyone alive has ever seen,” wrote Astronomy Magazine’s Michael E. Bakich.” But Karl Battams, a comet researcher at the Naval Research Laboratory, told Cosmic Log, “The astronomy community in general tries not to overhype these things. Potentially it will be amazing. Potentially it will be a huge dud.”

Regardless, the coming year will likely see conspiracy theorists asserting that the comet is on a collision course with Earth (as was said about Elenin). Astronomers, though, are certain that we’re in no danger of actually colliding with Comet ISON.

Comets are bodies of rock and ice that proceed along elliptical orbits, traveling billions of miles away from the sun and then coming inward, turning sharply around it at high speeds, and then going back out. This cycle can take anywhere from hundreds to millions of years.

A comet’s distinctive tail is made up of burning dust and gases that emanate from the comet as it passes by the sun. Solar radiation causes the dust to incinerate, while solar wind—an invisible stream of charged particles that is ejected from the sun—causes gases in a comet’s thin atmosphere to ionize and produce a visible streak of light across the sky.

Comet ISON’s current position as compared to the orbits of the inner solar system. Image via NASA

Ultimately, what Comet ISON will look like when it comes close depends on its composition. It could appear as a brilliant fireball, like the Great Comet of 1680, or it could disintegrate entirely before entering the inner solar system, like 2011′s Elenin Comet.

Its composition is difficult to predict because astronomers aren’t yet certain whether it is a “new” comet, making its first visit to the inner solar system from the Oort Cloud (a shell of comets that orbit the sun at great distance, roughly a light-year away) or whether it has passed us by closely before. “New” comets often burn more brightly while distant from the sun, as volatile ices burn off, and then dim when they come closer; returning comets are more likely to burn at a consistent rate.

One clue, though, indicates that its perihelion next year might be a sight to remember. Researchers have pointed out similarities between the path of this comet and of the Great Comet of 1680, which was visible in daytime and had a particularly long tail. If this is due to the fact that these two comets originated from the same body and at some point split off from each other, then Comet ISON might behave a lot like its 1680 cousin.

The distinct plumes of water and other organic compounds on Saturn's moon Enceladus. Image courtesy of NASA/JPL/Space Science Institute.

NASA’s Cassini spacecraft has revealed that Enceladus, a tiny moon orbiting beyond Saturn’s rings, may be capable of hosting some of the life forms found on Earth, NASA Science News reported today.

Planetary scientists using Cassini’s spectrometers found that more than 90 jets near the moon’s south pole are spurting water vapor, organic material, salt and icy particles through fissures. Essentially, it is snowing on Enceladus, and the snow’s composition is microbe-friendly, making this moon a prime candidate for gathering samples in the search for life.

“We can fly through the plume and sample it. Or we can land on the surface, look up and stick our tongues out. And voilà…we have what we came for,” Carolyn Porco, a planetary scientist and leader of the Imaging Science team for the Cassini spacecraft, said in the NASA report.

More critical reading and viewing to understand what we’ve learned about Saturn’s moons:

- An image of four distinct plums plumes at the south pole of Enceladus, from Cassini’s mission news earlier this week.

- Astrobiology.com’s explanation with an image of the “tiger stripes,” or fissures where water and ice sprays near the south pole of Enceladus.

- Scientific American‘s coverage last year of the discovery of water beneath Saturn’s icy moon Enceladus.

- Smithsonian’s story on Saturn’s two types of moons: those like Enceladus are similar to moons around other giant planets, such as Jupiter; the others are tiny, icy moonlets that reside on the outer edges of Saturn’s rings. They weren’t discovered until about 8 years ago when the Cassini spacecraft began imaging the Saturn system, and they were an unexpected find.

- A study published in Nature in 2010 found that Saturn’s moons formed from the accretion of material in the planet’s rings. When ring material moves beyond a certain distance from the planet—called the Roche limit—it becomes gravitationally unstable and clumps up to form the tiny moons.

- And Smithsonian’s story that year about the mystery of Saturn’s walnut-shaped moon, Iapetus.

What else have you read that’s great about Saturn’s moons? Let us know in the comments.

The first Death Star from Star Wars (via Wookieepedia)

Obi-Wan: That’s no moon. It’s a space station.

That space station was the Empire’s first Death Star in Star Wars: A New Hope. Obi-Wan and company had just bounced through a debris field, the remnants of the planet Alderaan. Such an act of destruction would seem impossible to us–it seemed so to many of the movie’s characters until it happened. But perhaps not, say three students at the University of Leicester in England who last year published a study on the subject in their university’s undergraduate physics and astronomy journal.

The study’s authors start off by making some simple assumptions: The planet being fired upon doesn’t have some sort of protection, like a shield generator. And it’s about the size of Earth but solid through and through (Earth isn’t solid, but the planet’s layers would have significantly complicated the math here). They then calculate the planet’s gravitational binding energy, which is the amount of energy required to pull apart an object. Using the mass and radius of the planet, they calculate that destruction of the object would require 2.25 x 10³² joules. (One joule is equal to the amount of energy required to lift an apple one meter. 10³² joules is a lot of apples.)

The energy output of the Death Star isn’t given directly in the movie, but the space station was said to have had a “hypermatter” reactor that had the energy output of several main-sequence stars. For an example of a main-sequence star, the authors look to the Sun, which puts out 3 x 10²⁶ joules per second, and they conclude that the Death Star could “easily afford to output [the energy required for an Earth-like planet's destruction] due to to its tremendous power source.”

It would be a different story, though, if the planet scheduled for destruction had been more like Jupiter than Earth. The gravitational binding energy of Jupiter is 1,000 times that of the Earth-like planet in the study. “To destroy a planet like Jupiter [the space station] would probably have to divert all remaining power from all essential systems and life support, which is not necessarily possible.”

Of course, that assumes that the Emperor wouldn’t be willing to sacrifice a space station full of people to wipe out his enemies. And considering that he was just fine with wiping out whole planets, I’m not sure I’d take that bet.

A composite image of S106, from the Hubble Space Telescope and Japan's Subaru Telescope (Credits: NASA/ESA/the Hubble Heritage Team (STScI/AURA)/NAOJ)

About 2,000 light years away, in the direction of the constellation Cygnus (The Swan), in a rather isolated part of the Milky Way, lies a newly formed star known IRS 4. This star, about 15 times the mass of our Sun, is still so young that it hasn’t yet calmed down; it’s ejecting material at high speed, giving this image its wings. That hydrogen gas, colored blue here, is heated by the star to temperatures of 10,000 degrees Celsius, making them glow. The cloudy, red parts in the image are tiny particles of dust illuminated by the star.

This area of the universe is known as star-forming region S106 and it’s pretty small (well, by universe standards), at only two light years from the edge of one “wing” to the other. The nebula is also home to more than 600 known brown dwarfs, “failed” stars that, because of their size, less than a tenth the mass of our Sun, cannot undergo the nuclear fusion that powers glowing stars.

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The best place to find "aliens" might be Comic-Con (2008, credit; Jim Merithew/Wired.com, via Wired Photostream on flickr)

A 2010 poll found that one in four Americans (and one in five people worldwide) believe that aliens have visited our planet. And many of these people believe that the evidence of these visits has been covered up by the government. Area 51, Roswell, mutilated cows in Colorado—there’s got to be some truth in that, right? And so two petitions were created on the White House We The People site, one calling “for the President to disclose to the American people the long withheld knowledge of government interactions with extraterrestrial beings” and the other asking the President “to formally acknowledge an extraterrestrial presence engaging the human race.”

The petitions easily reached the threshold of 5,000 signatures needed to get a response from the White House. But the signers are likely to be disappointed. Phil Larson, who works on space policy and communications at the White House Office of Science & Technology Policy, wrote in the response:

The U.S. government has no evidence that any life exists outside our planet, or that an extraterrestrial presence has contacted or engaged any member of the human race. In addition, there is no credible information to suggest that any evidence is being hidden from the public’s eye.

He gives a few examples of ongoing and planned research—SETI, Kepler, the Mars Science Laboratory—that may lead to the discovery of alien life and then reminds us that the odds of finding alien life are probably pretty slim:

Many scientists and mathematicians have looked with a statistical mindset at the question of whether life likely exists beyond Earth and have come to the conclusion that the odds are pretty high that somewhere among the trillions and trillions of stars in the universe there is a planet other than ours that is home to life.

Many have also noted, however, that the odds of us making contact with any of them—especially any intelligent ones—are extremely small, given the distances involved.

While reading this, I was reminded of a conversation I had with Cassie Conley last year when I was reported a story about what will happen should we actually find alien life. Conley is NASA’s Planetary Protection Officer; she’s the one who makes certain that NASA missions don’t contaminate other planets and that any sample return missions don’t harm us here on Earth. She told me that after she took the NASA job, some people befriended her in the hopes of ferreting out NASA’s secrets about aliens. “I was dropped as an acquaintance immediately upon their realizing that, in fact, I didn’t have any secrets,” she said. “They were disappointed when they found out there weren’t any.” (But at least she had a good attitude about it all: “It was rather entertaining,” she said.)

I will admit that it is possible that some grand conspiracy exists, that a government or corporation could be hiding this information from us all. (I can’t disprove a negative.) But keep in mind what Conley says: “If you think the U.S. government is that good at keeping secrets, you’ve got a lot higher opinion of them than I do.”

In addition, such a conspiracy would necessitate excluding the scientists most interested and most qualified in this area, and all of them have committed to making a discovery of alien life public. “I think there’s a big misconception in the public that somehow this is all a cloak-and-dagger operation,” says Arizona State University astrobiologist Paul Davies. “It’s not. People are quite open about what they are doing.”

Even the White House.

Anyone dressing up as a mad scientist today? (courtesy of flickr user contains_caffeine)

It’s Halloween and if you don’t have a costume yet, obviously you’ve got little time to put one together. But that’s OK, because we’ve dug up a few ideas for easy costumes with a science theme:

1 ) Mad Scientist: Yes, it’s an obvious one, but it will be easy to put together. All you need is messy hair, a geeky t-shirt (if you don’t have one, just take a plain shirt and write a few equations on it) and/or white lab coat, perhaps some safety goggles or protective gloves, and a glass container (a beaker or Erlenmeyer flask would be nice) with some colored liquid, bubbling away with the addition of some dry ice.

2 ) The Pacific Garbage Patch: This idea, from the Mother Nature Network, requires only some blue clothing and whatever bits of plastic you’ve got lying around the house. Glue or otherwise attach the plastic bits in a large patch to your outfit, get a little background info on the problem so you can inform anyone who asks, and you’ll be good to go.

3 ) Schrödinger’s Cat: This is a classic example of a feature of quantum physics in which something can be in two states simultaneously. Schrödinger’s Cat is in a box and is both dead and alive. For this costume, you’ll need a box to wear (at least over your head, like idea number 1 here) with a flap cut out for your face. Give yourself whiskers and a cute cat nose.

4 ) Squid: There are plenty of reasons to love these undersea creatures. But the ability to make a squid hat using nothing more than paper and a couple of CDs (as seen here on Discoblog) is another.

5 ) Dark Energy or Dark Matter: Find a “My Name Is” sticker and write “Dark Energy” or “Dark Matter” on it. No one knows what either of them looks like, so your guess (whatever you’re wearing) is as good as any other.

(And if you haven’t yet carved your pumpkin, be sure to check out these ideas from around the Smithsonian.)

An artist's conception of the star LkCa 15 and the nearby protoplanet. (Credit: Karen L. Teramura, UH IfA)

Planets form from disks of swirling material that condense into solid bodies. Once only a theory, this formation has now been caught in the act by scientists using telescopes at the W.M. Keck Observatory in Hawaii (a site that should be familiar if you’ve read the Smithsonian story on black holes). The planet’s name is LkCa 15 b and researchers say it’s a protoplanet (below, in blue), still surrounded by cool dust and gas (in red). “We…found a planet, perhaps even a future solar system at its very beginning,” says the University of Hawaii’s Adam Kraus, lead author of the study that will appear soon in the Astrophysical Journal.

The planet LkCa 15 b appears in blue surrounded by cooler dust and gas in red, near the star LkCa 15. (Credit: Kraus & Ireland, 2011)

Kraus and his co-author, Michael Ireland of Australia’s Macquarie University, made their discovery by combining two techniques to cancel out the light from bright stars. The first is adaptive optics, which uses powerful computers to rapidly manipulate the telescope’s mirrors and adjust for distortions caused by Earth’s atmosphere. The second is aperture mask interferometry, and it further improves the resolution of the telescope. “We can manipulate the light and cancel out distortions,” Kraus says. They pointed the telescope at the star LkCa 15, canceled out the star’s light and there it was, a newly forming planet.

“LkCa 15 b is the youngest planet ever found,” Kraus says. “This young gas giant is being built out of the dust and gas….For the first time, we’ve been able to directly measure the planet itself as well as the dusty matter around it.”

Phil Plait, at Bad Astronomy, has more details:

The disk’s hole is about 8 billion km across. Disks like this are seen around other stars, and it’s generally thought that the hole is caused by a planet orbiting inside that region sweeping up material. In this case, that looks to be true! If the planet is in a circular orbit, it’s about 2.5 billion kilometers from its star, a little closer to its star than Uranus is from the Sun (it’s not known if the orbit is circular or elliptical; that’ll take a few years of observations as the planet physically moves around the star and the orbit can be calculated). The planet is much hotter than you might expect, but that’s because it’s so young: material is falling onto it, heating it up. That’s why it’s glowing in the infrared.

…Nothing like this has been seen before in a planet so young! That’s scientifically quite important. Our models of how planets form are complex, and we need detailed observations to see if the models are correct or not. Since planet formation is a process, we need observations of it at different stages, including very early on. That’s crucial, since it represents the transition period between the time before planets start to form in the disk, and the time when the planets are all finished and tidied up. We’ve seen both of those before, so this observation is a first.

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The Very Large Array in New Mexico (via wikimedia commons)

The Very Large Array, a collection of 27 radio antennas out in New Mexico, has a problem—it has a boring name. That hasn’t stopped the thousands of scientists who have used the array since 1980 from making observations of our universe. But with an expansion of the array on schedule to be completed next year, the National Radio Astronomy Observatory, which runs the array, has decided that it’s time for a change.

“Though the giant dish antennas, the unique machines that move them across the desert, and the buildings on New Mexico’s Plains of San Agustin may appear much the same, the VLA truly has become a new and different facility. We want a name that reflects this dramatically new status,” says NRAO director Fred K.Y. Lo. “The new name should clearly reflect the VLA’s leading role in the future of astronomy, while honoring its multitude of past achievements.”

Those achievements include: receiving radio communications from the Voyager 2 spacecraft as it flew past Neptune; key observations of Sgr A*, at the center of the Milky Way, now known to be a black hole; discovery of the first Einstein Ring; as well as contributions to many other investigations of stars, galaxies, black holes and other astronomical phenomena.

In addition, the Very Large Array has often appeared in pop culture, a perfect stand-in whenever a mysterious telescope might be needed in movies such as Contact, Armageddon and Transformers: Dark Side of the Moon. You may even have gotten the mistaken idea that the VLA conducted searches for SETI from the movie Independence Day.

There are several ways to go when naming a telescope. Name it after a famous person in astronomy, like the Hubble, or after a place, like Arecibo. Acronyms are always a favorite in science, like CARMA. Or you could be more creative and go in a different direction, perhaps making up something based on a future goal (the Planet Finder 9000?) or a dream.

If you’ve got an idea for what to rename the VLA, tell us in the comments below and also submit it here by 23:59 PST, December 1, 2011. The winning name will be announced at the American Astronomical Society meeting in Austin, Texas on January 10, 2012.

A combined image from the Chandra and XMM-Newton X-ray observatories of RCW 86, which was determined to have started out as SN 185 (Credits: ESA/XMM, NASA/CXC, University of Utrecht (J. Vink))

Astronomers are getting a bit of a treat this week—they’re watching a supernova exploding 21 million years ago (that is, 21 million light years away) in the Pinwheel Galaxy. That’s pretty close for a supernova (they’re usually around a billion light years away), and you might even be able to see it with a simple pair of binoculars. But what was the first supernova?

OK, that was a trick question. We can’t know what was the first star to explode. But we can look at the first recorded supernova, SN 185.

In 185 A.D., someone in China looked up in the night sky and saw a new star. It sparkled and did not move, so it couldn’t be a comet. This “guest star” stayed in the sky for eight months and then disappeared forever; it was recorded in the Book of the Later Han, which told the history of China from 25 to 220 A.D.

The guest star was a supernova, a star that had run out of fuel and then collapsed in on itself in a thousandth of a second. The core of the star heated to a billion degrees and destructive gamma rays were produced. Neutrinos were generated in huge quantities. Only a tiny fraction were absorbed by the stellar gas, and they had so much energy they ripped apart the outer layers of the star. This violent explosion, which could have been brighter than an entire galaxy, also produced X-rays, gamma rays and ultraviolet light. The resulting shock wave produced radioactive elements such as cobalt and titanium. Any planet too close to such a destructive event would have been torched.

In 2006, scientists using the Chandra X-ray Observatory and the XMM-Newton Observatory determined that the supernova remnant RCW 86 was the leftover bits of SN 185. They calculated how fast the energized shell of the remnant was moving to estimate the original date of the supernova and determined that the star had gone supernova about 2,000 years ago. Scientists had thought RCW 86 might be SN 185 because the remnant’s location matched historical records of the supernova, but previous calculations gave the remnant an age of 10,000 years. It appears those calculations were based on measurements of a part of the shock wave that had encountered a region of dense matter and slowed down.