The yellow spots represent icy areas.
Ice? On the planet closest to the Sun? You heard right: Mercury’s northern pole may have craters containing frozen water.
The evidence, presented in three papers published last week in Science, comes from several sources. The Mercury Laser Altimeter, an instrument on the Mercury space probe, MESSENGER, helps scientists map the topography of the planet by firing lasers at its surface and recording the time it takes for the light to return. The instrument also records the intensity of the return beams, and the bright spots reflecting off Mercury’s surface suggest the presence of ice. Read More
Golden and gleaming, this convex mirror arrived last week at the Goddard Space Flight Center in Greenbelt, Md., where it will be mounted on the much-anticipated Webb telescope. When the telescope is up and running, sometime later this decade, the Webb will take the title of the most powerful space telescope ever built, ousting even the Hubble. The Boulder-built mirror’s color comes from a microscopic layer of gold, 1,000 times thinner than a human hair. The gold will help the telescope better reflect infrared light, making distant planets and the universe’s first galaxies easier to see.
Image Credit: Chris Gunn, NASA
Artist’s rendering of binary system Kepler-47, with outer planet Kepler-47c
in the foreground and inner planet Kepler-47b in the bottom right corner
Growing up in a binary star system can be tough. As the system’s two suns orbit each other, they exert strong gravitational pressures capable of pushing away young planets or sending them careening into one another. It wasn’t until last year that astronomers found the first evidence of a world orbiting two stars. Now new data has revealed that the binary system Kepler-47 goes one step further: it contains not one but two planets.
What’s the News: If you were to bring a glass of water to Mars, the liquid would instantly boil because the Red Planet’s carbon dioxide atmosphere is so thin: The vapor pressure of the water easily surpasses the weak atmospheric pressure, sending water molecules flying off quickly into the atmosphere. However, ancient shorelines and river-like features indicate that Mars had a watery past, leading researchers to wonder what happened to Mars’ once-thicker atmosphere. Now, data from the Mars Reconnaissance Orbiter has uncovered a massive deposit of solid CO2 at the south pole that could double the planet’s atmospheric pressure if it were released as gas. “If you double the amount of CO2 in the atmosphere, it’s quite possible that you could have liquid water,” planetary scientist Philip James of the Space Science Institute in Boulder told Scientific American. “People have suggested that this could happen, and now it looks like it could be possible.”
What’s the News: Looking at images of odd undulations in the rings of Saturn and Jupiter, astronomers have discovered that comets are to blame. The finding means that a planet’s rings act as a historical record of passing comets, possibly leading to a better understanding of comet populations. “We now know that collisions into the rings are very common—a few times per decade for Jupiter and a few times per century for Saturn,” Mark Showalter, from the SETI Institute in Mountain View, California, told the Daily Mail. “Now scientists know that the rings record these impacts like grooves in a vinyl record, and we can play back their history later.”
Planetar. Substar. Failed star. Sub-stellar object. Astronomers have pinned each of these monikers on brown dwarfs, a category that has always perplexed scientists because it raises questions about what it means to be a star or a planet. And if that wasn’t enough, now they’ve discovered the coldest brown dwarf yet, blurring the line between planet and star even further.
It’s name is CFBDSIR J1458+1013B, and may be cooler than the boiling point of water (at the pressure of Earth’s atmosphere). This strange body is about 75 light-years from us, where it orbits its binary partner, another brown dwarf. Using the infrared capabilities of the 10-meter Keck II Telescope on Mauna Kea, University of Hawaii researcher Michael Liu and his team estimated the brown dwarf’s temperature, and have a ballpark range for its mass: between 6 and 15 times the mass of Jupiter.
It’s special because it may be a class Y dwarf (temperature less than 225 degrees Celsius (440 F)), a type of object whose existence astronomers had predicted but never actually found. Before this candidate arose, the coolest known brown dwarf was in the T spectral class; while there have been a few Y-class candidates in the past, scientists have a better grasp on the temperature of this one: 97 degrees Celsius, plus or minus 40C.
Saturn and its moons may owe their distinctive looks to a legacy of destruction.
First, the magnificent rings of the sixth planet: Although astronomers have gazed at the rings for centuries, experts are still debating exactly how these loops formed. Now a new study in the journal Nature proposes that the rings are the leftovers of a large moon that was torn asunder when Saturn’s gravity reeled it in four and a half billion years ago. Lead researcher Robin Canup says this theory explains both how the rings got there, and why they’re made of nearly solid ice.
In the new study, Canup calculated that a moon the size of Titan — Saturn’s largest at some 5,000 kilometers across — would begin to separate into layers as it migrated inward. Saturn’s tidal pull would cause much of the moon’s ice to melt and then refreeze as an outer mantle. As the moon spiraled into the planet, Canup’s calculations show, the icy layer would be stripped off to form the rings. [Science News]
That layered removal is the key to Canup’s explanation, which we covered briefly when she first presented the idea at a meeting in October. Other explanations for the rings’ formation include a comet crashing into a moon, or Saturn pulling in a moon and causing it to shatter all at once. Those events would create a cascade of small objects that Saturn’s gravity could have coalesced into rings, but it would seem that they would have created much rockier rings. In reality, Saturn’s are 95 percent ice.
The bits that make up Earth apparently took their time pulling themselves together. New research hints that our home didn’t form as a fully-fledged planet until 70 million years after its currently accepted birth date, making the planet younger than scientists believed.
The evidence appears in Nature and looks at the Earth’s “accretion”–the swirling together of gas and dust that formed our planet. Researchers previously believed that the Earth’s accretion was a fairly steady process, happening in about 30 million years, but this study suggests that Earth took a lot longer to form.
“The whole issue hinges on working out how long it took for the core of the Earth to form, which is one of the big unknowns in this area of science,” said Dr. John Rudge, one of the authors at the University of Cambridge. “One of the problems has been that scientists usually presume Earth’s accretion happened at an exponentially decreasing rate. We believe that the process may not have been that simple and that it could well have been a much more staggered, stop-start affair.” [The Telegraph]
Astronomers keep turning up new exoplanets, and as the count rises, they keep edging closer to finding worlds like our own pale blue dot. Astronomer Jay Farihi thinks Earth-like worlds might be even more common in the universe than previously expected, based on evidence from rocky planets few astronomers are studying: The ones that don’t exist anymore.
Farihi’s research subjects are white dwarfs. In our galaxy, about 90 percent of stars will end their lives in this incredibly dense state once the star sheds its outer material and only the core remains. This is the fate of our sun. White dwarfs usually have atmospheres composed of the light elements helium and hydrogen, as the heavy elements have settled to the core. But about 20 percent of white dwarfs are different, showing heavy elements—what astronomers call “metals”—in their atmospheres. For decades, astronomers attributed this metallic pollution to the interstellar medium, the thin gas that permeates the space between stars. The idea was that white dwarfs were old stars that had been on several orbits around the Milky Way and had picked up bits of the interstellar medium as they went around [Space.com]. But Farihi thinks those elements are evidence of something else.
The moment you read this, volcanic eruptions could be happening on Venus.
Planetary astronomers have been debating whether Venus is or was geologically active, and whether the geologic hotspots previous missions saw mean that Venus is one of the few places in the solar system to have experienced volcanism. Now, according to data from the European Space Agency’s Venus Express mission, there’s every reason to believe that Venus not only has been geologically active and volcanic during its lifetime, but also might still be today, according to Jörn Helbert, coauthor of the study in Science. “The solidified lava flows, which radiate heat from the surface, seem hardly weathered. So we can conclude that they are younger than 2.5 million years old — and the majority are probably younger than 250,000 years…. In geological terms, this means that they are practically from the present day” [Wired.com].