sciencehabit writes: A fluorescent glow high in the atmosphere of Titan, Saturn's largest moon, signifies the presence of a gas that astronomers have yet to identify. The glow appears only on the daytime side of the moon at altitudes between 600 and 1250 kilometers, with the largest intensity occurring at an altitude of about 950 km. Detailed analyses reveal that the glow doesn't stem from a problem with the Saturn-orbiting Cassini craft, and it isn't associated with methane or any of the other hydrocarbons already identified as constituents of Titan's atmosphere.
sciencehabit writes: Material dissolved in the ocean of Jupiter's moon, Europa, which lies beneath an icy shell estimated to be about 100 kilometers thick, nevertheless reaches the surface, new research suggests. The new findings are exciting because they suggest that material that accumulates on Europa's surface might be making its way down into the ocean, where sulfur-bearing compounds could serve as nutrients for microbial life if any exists there.
sciencehabit writes: Some "super-Earths" will never evolve to resemble our planet, a new study suggests. Researchers looked at seven of these worlds—distant planets whose mass lies between one and 10 times ours, evaluating how the x-ray and extreme ultraviolet radiation emitted by their parent stars might affect their atmospheres over their remaining lifetimes. Even though many of the planets orbit their stars very closely and have high temperatures, which in turn causes their hydrogen-rich atmospheres to expand and a fraction of the gases to escape the planet over time, it's unlikely that the planets will lose enough of their atmosphere to become rocky bodies like Earth. And if any planets similar to these orbit in their parents stars' habitable zone, substantially farther from the home star where liquid water might more likely exist, their atmospheres will lose even smaller amounts of hydrogen-bearing compounds over time, the researchers note. So, instead of thinking of these planets as super-Earths, astronomers should probably think of them as "mini-Neptunes"—a planet in our solar system that weighs about 17 times the mass of Earth and is swaddled in hydrogen-rich gases. Even if these mini-Neptunes never become habitable, however, many scientists have previously proposed that any smaller, rockier Earth-sized moons orbiting the gas giants could nevertheless host life as we know it.
sciencehabit writes: What do you do if you're a hot Jupiter and want to cool off? Why, you use your gravity to lift up the surface of your sun, cooling it and creating a dark spot on the star. In a forthcoming issue of The Astrophysical Journal Letters, astronomers will report using the Kepler spacecraft to observe the brightness of a star in the constellation Cygnus more than a million times. Named HAT-P-7, this star has a hot Jupiter—a giant planet orbiting close-in —which other scientists found before NASA launched the spacecraft. The world's gravity raises the star's surface away from its hot center, causing part of the surface to cool by just a fraction of a degree Kelvin and produce a dark spot that lags behind the planet's position by a few hours. If confirmed, this discovery is the first time astronomers have ever seen planet-induced "gravity darkening" and demonstrates Kepler's remarkable ability to detect even the subtlest of stellar signals.
sciencehabit writes: A nebula 18,000 light-years away bears a startling resemblance to Earth's humble manatee — down to the "scars" on its back. Scientists already knew of the giant cloud, called the W50 nebula, which formed when a star went supernova 20,000 years ago. But a new image of it taken by the National Science Foundation's Karl G. Jansky Very Large Array (VLA) telescope , has inspired a new name for the object: the Manatee Nebula. The nebula received its moniker after someone at the National Radio Astronomy Observatory noticed its resemblance to a manatee floating on its back, flippers over tummy. Bright arcs formed by powerful jets of charged particles in the massive cloud mirror the curved boat propeller scars the endangered animals often bear. And like its namesake, the Manatee Nebula is a whopper: It's 700 light-years across, one of the biggest supernova remnants ever spotted by VLA.
sciencehabit writes: Last November, astronomer David Turner made headlines by claiming that one of the sky's best known objects—the North Star, Polaris—was actually 111 light-years closer than thought. If true, the finding might have forced researchers to rethink how they calculate distances in the cosmos as well as what they know about some aspects of stellar physics. But a new study argues that distance measurements of the familiar star made some 2 decades ago by the European Space Agency's venerable Hipparcos satellite are still spot on. Experts appear to agree.
sciencehabit writes: Long before Star Trek's Mr. Spock, many astronomers during the 19th and early 20th centuries thought a planet named Vulcan circled the sun inside the orbit of Mercury and tugged on the latter, accounting for peculiarities in Mercury's motion. Well, Vulcan doesn't exist—Albert Einstein's general theory of relativity explains Mercury's orbit—but asteroids known as vulcanoids could, circling so close to the sun that we can't see them in its glare. If vulcanoids are real, they're only 7% to 21% as far from the sun as Earth is: closer than that and they evaporate in the sun's heat, farther than that and Mercury kicks them away. Now, in the March issue of Icarus, astronomers report results of a search using STEREO, two NASA spacecraft that revolve around the sun near Earth's orbit. The scientists found no new objects, ruling out the existence of any vulcanoids larger than about 6 kilometers, which is less than half the mean diameter of the little martian moon Deimos. But the search would have missed smaller vulcanoids, so an even deeper exploration might be, as Spock would say, the logical thing to do.
sciencehabit writes: The Curiosity rover has entered a martian terrain offering clear signs of ancient water and tantalizing hints of a scientific bonanza. In a press teleconference, NASA rover team members reported the discovery of mineral-filled veins and small mineral spheres that require that water once saturated the muddy floor of Gale crater. But geologists are particularly enticed by the sedimentary rock that Curiosity has roved across on its way from its landing site. As it descended deeper into the exposed strata and farther back in geologic time, it first encountered pebbles and cobbles laid down in deep torrents of water, then sandy sediments deposited by less turbulent currents, and finally fine, silty sediments. The silty sediments speak of a far quieter time in Gale, perhaps when a placid lake filled the crater. Lake sediments are the ideal place to look for organic matter lingering from ancient martian life, which is what Curiosity will do when it begins rock drilling in a few weeks.
sciencehabit writes: Astronomers have discovered the largest structure yet seen in the universe, a clump of quasars so large that it would take light 4 billion years to traverse its widest dimension. The structure is so large that it challenges Albert Einstein's cosmological principle—the notion that the universe, at large scales, looks the same no matter the direction and locale from which you look. Bringing the comparison to our cosmic neighborhood, the new record-holding group of quasars spans about 1600 times the distance between our Milky Way galaxy and our neighbor Andromeda.
sciencehabit writes: Something is orbiting the bright star Fomalhaut in the constellation known as the Southern Fish, but no one knows exactly what it is. New observations carried out last year with the Hubble Space Telescope confirm that the mysterious object, known as Fomalhaut b, is traveling on a highly elongated path, but they haven't convincingly nailed down its true nature. But if it is a planet, as one team of astronomers thinks, we may be in for some celestial fireworks in 2032, when Fomalhaut b starts to plough through a broad belt of debris that surrounds the star and icy comets within the belt smash into the planet's atmosphere.
sciencehabit writes: New observations suggest that the Milky Way weighs in at a "mere" 500 billion to 1000 billion times the mass of the sun—less than half as much as astronomers had previously estimated. A lower total mass for our home galaxy would have several implications, in particular for the Milky Way's dark matter content and distribution. Current theories predict that galaxies like ours should be surrounded by hundreds or even thousands of smaller satellite galaxies—many more than astronomers have found. The new estimate could potentially help explain the discrepancy, van der Kruit says, because a smaller galaxy can't attract as many followers.
sciencehabit writes: Imagine life on a spaceship headed to Mars. You and your five crewmates work, exercise, and eat together every day under the glow of fluorescent lights. As the months pass, the sun gets dimmer and communication with Earth gets slower. What does this do to your body? According to an Earth-based experiment in which six volunteers stayed in a windowless "spaceship" for nearly a year and a half, the monotony, tight living space, and lack of natural light will probably make you sleep more and work less. Space, for all intents and purposes, turns you into a couch potato.
sciencehabit writes: A meteorite blasted from the surface of Mars contains traces of water, according to a new study. Though the fist-sized rock is relatively dry by earthly standards, it contains between 10 and 30 times the average concentration of water found in other known martian meteorites—and it is the first to closely match certain aspects of the martian crust. The proportions of various oxygen isotopes in the water don't match those found on Earth, a sign that the water likely originated on the Red Planet either as part of the magma fueling the volcano or as ground water that infiltrated or reacted with the molten material after it cooled. The finding bolsters the notion that Mars may have long ago boasted a much warmer and wetter surface than it has today.
sciencehabit writes: Astronomers have discovered what may be five planets orbiting Tau Ceti, the closest single star beyond our solar system whose temperature and luminosity nearly match the sun's. If the planets are there, one of them is about the right distance from the star to sport mild temperatures, oceans of liquid water, and even life.
sciencehabit writes: On 15 January, the XMM-Newton satellite detected a bright source of x-rays in the Andromeda galaxy, 2.5 million light-years from Earth. As astronomers report online today in Nature, the x-rays arise from hot gas swirling around a black hole that tears the material from an orbiting star. The object is roughly 10 times as massive as our sun and gobbles matter at nearly the maximum possible rate. Four similarly ravenous black holes are known in the Milky Way, but dust in the galaxy's disk obscures observations; so studying the newfound beast in Andromeda may offer fresh insight into how black holes accrete material, a process that feeds the supermassive black holes powering quasars billions of light-years away.