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].
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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].
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Which celestial bodies are more likely to host extraterrestrial life: Saturn’s hazy moon Titan and water-spewing moon Enceladus, or Jupiter’s icy moons Europa and Ganymede, which may have liquid oceans beneath their frozen crusts? That’s the difficult question facing NASA and the European Space Agency (ESA) as they try to decide where to send the next planetary probe. By the end of this month, agency officials plan to pick a destination for a massive mission, costing nearly US$4 billion, to be launched around 2020 for the distant reaches of the Solar System. The battle pits Titan, which recent discoveries have made the cool new kid on the block, against Jupiter’s moon Europa, which has long sat atop community wish lists [Nature News].
In advance of that decision, the space agencies have released details of the dueling proposals. The potential Saturn mission would follow up the remarkable discoveries made by the Nasa/Esa Cassini-Huygens mission which continues to operate at the ringed planet…. Cassini has sent back data that indicates Titan is akin to a primitive – albeit frozen – Earth. It has a thick atmosphere and is rich in organic (carbon-rich) molecules [BBC News]. The plan calls for an orbiter that would release a hot air balloon to drift in Titan’s hazy atmosphere and would drop a lander to the surface, where it could float on one of moon’s lakes of liquid ethane and methane. The orbiter would also dip into the atmosphere of Enceladus, which has fired imaginations with the revelation that it has geysers that spew jets of icy water into space.
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