Saturn and Jupiter are examples of gas giants—huge, uninhabitable planets
composed of gas rather than solid matter. Based on observations of these planets and models of their evolution, astronomers have long believed [pdf] that they form by guzzling gas from young stars. This week, courtesy of a telescope in the deserts of Chile, astronomers reported seeing the first direct evidence of gas giant formation.
Astronomers were observing a young star
called HD 142527, some 450 light years from Earth. Like most young stars, HD 142527 is surrounded by a disk of gas and dust—remnants of the star’s conception that continue to circle the star for millions of years . But there was something strange about this particular star’s disk. Astronomers observed a large gap in the gas and dust, which, as reported in Nature this week, they believe is caused by an up-and-coming gas giant.
Pulling together decades of data from the Voyager, Galileo, Cassini, and New Horizon probes, as well as the Hubble Space Telescope, scientists at the US Geological Survey have put together a complete geological map of Io, the beautiful, mysterious Jovian moon. Io is the most volcanically active object in the solar system, and its surface reflects that: unlike everything else around, it has no craters, a sign that its surface is constantly being remade. That’s thanks to volcanoes that shoot out more than 100 times more lava per year than Earth’s.
The map is a lovely thing, and you can play around with it yourself here.
What’s the News: Jupiter’s moon Io is more volcanically active than any other object in our solar system, releasing 30 times more heat than Earth through volcanism. It’s thought that Jupiter’s gravity pulls so hard on the moon and causes so much friction that the resulting thermal energy melts a huge amount of underground rock, feeding Io’s 400 active volcanoes.
For years, astronomers have debated whether Io’s spewing lava comes from isolated pockets of magma or a layer that spans the entire moon. Astronomers have now peered into Io’s interior for the first time, discovering that it has a global sea of magma roughly 30 miles thick. “It turns out Io was continually giving off a ‘sounding signal’ in Jupiter’s … magnetic field that matched what would be expected from molten or partially molten rocks deep beneath the surface,” lead researcher Krishan Khurana told Wired. Read More
In August 2006, Pluto received its official demotion to dwarf planet status, taking our solar system down to eight planets. In August 2010, exoplanet hunters say they’ve found a haul of new worlds around a single star; that alien solar system may have seven known planets, meaning the system could be more like our home system than any ever discovered. And one of those worlds could be the smallest exoplanet ever found, too.
The star these planets orbit is called HD 10180, and it lies 127 light years from here. Astronomers at the European Southern Observatory in Chile used a spectrograph called HARPS to track tiny variations in the starlight caused by the pull of the planets.
It found clear evidence for five giant planets similar in size to Uranus or Neptune in our own solar system. But there were also tantalising signs that two other planets are also present, one of which would be the smallest, or least-massive, yet found orbiting another star [Christian Science Monitor].
We silly humans tend to think of rain just in our own terms, the falling water tainted with various toxins that draws out our umbrellas and cancels our baseball games. But across the solar system, it rains on other worlds with thick atmospheres–it’s just not rain we would recognize. On Saturn’s moon Titan, for instance, it rains methane. And now, a group of scientists says in Physical Review Letters, computer simulations have confirmed that it rains helium on Jupiter.
The term “rain” applies loosely here, because the hellfire precipitation happening on Jupiter isn’t much like a pleasant afternoon shower here on Earth. Droplets of helium form thousands of miles below the tops of hydrogen clouds, at temperatures around 9,000 degrees Fahrenheit–the helium stays in fluid form because of the planet’s high atmospheric pressure. Pressures and temperatures on Jupiter are so high that the droplets of liquid helium are falling through a fluid of metallic hydrogen [Space.com].
Here’s one benefit of a storm so ferocious that it rages on for centuries–scientists have plenty of time to observe it, and to wait for technology to improve so they can get an even better look.
The solar system’s biggest storm swirls on the giant gas planet Jupiter; it’s a tempest that goes by the name the Great Red Spot. Now, for the first time, scientists have constructed a detailed interior weather map of the giant storm system using thermal images from the European Southern Observatory’s Very Large Telescope and other powerful ground telescopes.
Peering into the Great Red Spot, scientists found that there were surprising weather and temperature variations within the spot and that the dark red area in the spot’s center is actually a warm patch in the storm. The observations are detailed in the journal Icarus, and give researchers a better understanding of circulation patterns within this Jovian storm. Says Glenn Orton, the Jet Propulsion Laboratory astronomer who led the study: “We once thought the Great Red Spot was a plain old oval without much structure, but these new results show that it is, in fact, extremely complicated” [Wired].
While Jupiter’s two largest moons, Ganymede and Callisto, are nearly the same size, they’re far from identical twins. Now, in a Nature Geoscience study, Amy Barr and her team might have figured out this tale of two similar moons with very different histories.
Voyager and Galileo mission images showed Ganymede, seen here on the right, to be a geologically active place, with a surface that scientists think changes through tectonic processes like those that we have here on the Earth. Callisto, seen on the left, looks totally different: Its rock and ice have not mixed in the same way, and it doesn’t seem to have such active geology, despite being approximately the same size as Ganymede. For 30 years, researchers have wondered what process could have got enough heat into Ganymede to drive its geological evolution without setting off Callisto as well [ScienceNOW Daily News].
On January 7, 1610, Galileo Galilei pointed his “spyglass” to the heavens and stared up at Jupiter, one of the brightest lights in the evening sky, and noted what he at first assumed to be three bright stars near the planet. But over the following nights, he realized that those three bright bodies weren’t fixed in the heavens like stars, but rather seemed to dance around Jupiter along with a fourth, smaller body.
Galileo triumphantly announced his discovery of four “planets” that revolved around Jupiter in his March treatise, Starry Messenger [pdf]. Thinking of his pocketbook, he dutifully proposed naming them the Medicean Stars in honor of his patron, Cosimo de Medici. But the name didn’t stick, and today we honor the scientist rather than the patron by calling Jupiter’s four largest satellites the Galilean moons.
The discovery dealt a death blow to the Ptolemaic understanding of the universe, in which all planets and stars were believed to orbit the Earth. For, as Galileo wrote in his treatise, “our own eyes show us four stars which wander around Jupiter as does the moon around the earth.”
In the 400 years that have passed since Galileo first laid eyes on them, we’ve learned a great deal about the moons Io, Europa, Ganymede, and Callisto (all named after the mythological paramours of Jupiter). If all goes according to plan we’ll soon get to know them much more intimately–NASA and the European Space Agency are currently planning missions to closely observe three of the moons. Click though this gallery to view NASA’s most stunning photos of the four satellites, and to find out what we’ve discovered in the four centuries since Galileo began the work.
(For more on Galileo’s discovery and what it meant to science, check out this post from DISCOVER’s Phil Plait.)
The mighty planet Jupiter has 63 official moons, but it turns out there’s always room for more. Researchers used computer models to map the past trajectory of the comet 147P/Kushida-Muramatsu, and determined that for about 12 years it circled Jupiter as a temporary moon. At the ongoing European Planetary Science Congress, astronomers declared that the comet completed two complete orbits of the gas giant, and remained in orbit from 1949 to 1961.
The 1,300-foot-wide comet had a happier fate than other comets that got too close to Jupiter, and were dragged all the way in for a crash landing. Only one temporary satellite has been observed falling prey to a planet’s pull: comet Shoemaker-Levy 9, which broke apart and crashed into Jupiter in 1994…. Unlike [Shoemaker-Levy], comet Kushida-Muramatsu eventually escaped Jupiter’s gravity. It currently circles the sun in the solar system’s asteroid belt, between the orbits of Mars and Jupiter [National Geographic News].
Jupiter is sporting a new, Earth-sized scar near its south pole, and NASA has confirmed that the gas giant was thumped by a massive impact over the past few days. The discovery was made Sunday night by a Australian computer programmer who uses his spare time to stargaze with his backyard telescope, and today NASA declared that the dark spot is definitely not a weather system, and is indeed evidence of a collision. It’s not yet known exactly what smacked into Jupiter; astronomers say it could have been an unknown comet, or a stray piece of ice.
This is only the second time such an impact has been observed. The first was almost exactly 15 years ago, when more than 20 fragments of comet Shoemaker-Levy 9 collided with the gas giant. “This has all the hallmarks of an impact event, very similar to Shoemaker-Levy 9,” said Leigh Fletcher, an astronomer at NASA’s Jet Propulsion Lab…. “We’re all extremely excited” [New Scientist].