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The Last Month in Astronomy


MAY-09-2012 • Vesta News • NASA’s Dawn spacecraft is showing that Vesta is more like the Earth’s moon than a typical asteroid. It appears to have an iron core. In fact, it probably had a magma ocean which means it underwent differentiation where distinct layers are created. This confirms that a particular group of meteorites found on Earth originated on Vesta, probably 6% of all meteorites that fall to Earth.

MAY-08-2012 • Spitzer “sees” Super Earth • The Spitzer infrared observatory has directly measured light from a Super-Earth sized exoplanet. Usually it is impossible to see light from an exoplanet because it is lost in the glare of its star. But in the infrared the ratio is not quite as bad.

MAY-03-2012 • Opportunity still rocking • The Mars Rover Opportunity, already 8 years beyond its expiration date, has found “the strongest evidence for water that we’ve ever seen with Opportunity” according the PI Steve Squyres of Cornell. The other rover, Spirit, stopped communicating in 2010. The next rover, Curiosity, should land on Mars on August 5.

APR-30-2012 • Pre-planetary Nebula • By now you know that when astronomers talk about planetary nebulae, they don’t mean anything related to planets. But pre-planetary nebulae are different. One such nebula is the Egg Nebula. Hubble recently imaged this object (see image on the left). The central star cannot be seen, in fact, it might be a binary star system. The nebula is 3000 light-years away although that distance has large error bars. The image was taken with Hubble’s Wide Field Camera 3. Credit: ESA/Hubble, NASA

APR-26-2012 • Peter J. does it again • Peter Jenniskens had uncovered some meteorites fragments after a large meteor was seen over California. These fragments were found in the Gold Country. Later he and Mike Koop found more fragments from the air. The original meteor is estimated to weigh more than 154,000 pounds. An event of this size occurs about once a year. This event occurred on April 22. ;

APR-25-2012 • Earth under attack • A pair of studies published in Nature gives evidence that the heavy bombardment of Earth lasted much longer than previously believed. In fact it lasted for almost the entire first half of Earth’s history. Earlier computer simulations suggested the Late Heavy Bombardment (LHB) lasted from 4.1 billion to 3.8 billion years ago. Calling this into question is the large number of large lunar craters that are much younger than 3.8 billion years old. Instead, the asteroid belt, currently starting 2.1 AU from the Sun, might have started just 1.7 AU up until 2 billion years ago. This would cause many more objects to become dislodged from the belt and come barreling into Earth. To bolster this idea another study looked for the results of large impacts on Earth. Brandon Johnson from Purdue University says “Our work shows that a lot more big asteroids – meaning dinosaur-killer or larger – were hitting Earth well after the current idea of when it ended.”

APR-24-2012 • Galaxy Schizo • It seems the galaxy NGC4594, aka The Sombrero Galaxy, has two personalities. In visible light it appears to be a fairly typical spiral galaxy with a rather bright halo. But in infrared light (thank you Spitzer satellite observatory) the galaxy appears to be an elliptical galaxy. “The Sombrero is more complex than previously thought,” according to Dimitri Gadotti of the ESO in Chile. “The only way to understand all we know about this galaxy is to think of it as two galaxies, one inside the other.”


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