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Science News for the Week, Aug 6-12

August 13, 2011 - Saturday

Too much good stuff!

• This week marks the 20th anniversary of arXiv, the open access online database of research papers for physics and related fields. It's hard to underestimate how arXiv has revolutionized and democratized the distribution of knowledge in physics. In a great article, the founder Paul Ginsparg reflects on two decades of sharing results rapidly online and discusses its future. It will be interesting to see if the other physical sciences follow the example of physics in the coming years.

• There was a lot of hoopla this week about SETI (the search for extraterrestrial intelligence) coming back online after donors contributed over $200,000. Besides providing an opportunity to gain some media attention, it's not clear to me what the big deal is. This amount of money is not much when you consider that the Allen Telescope Array costs millions of dollars a year to operate. Just as a comparison, in the same time period Zach Weiner and friends have raised over $70,000 for a video webseries (which should be awesome by the way).

• After 3 years and 13 miles, the rover Opportunity reached the rim of a new crater it will be exploring on Mars (yeah, traveling around on Mars is a little slow). The crater is older than where Opportunity explored before, and there is evidence for clay sediments that may tell us something about the early history of the planet. Opportunity will probably continue to explore this crater for the next few years until it goes kaput.

• The satellite PAMELA found evidence for a belt of antiprotons circling the Earth. This has long been theorized, but this is the first confirmation. Antiprotons are just like protons, but with opposite charge. Every particle has an antiparticle pair, and the two annihilate each other when they come into contact. When high energy particles (like those coming from the Sun) strike the Earth's atmosphere, they sometimes create antineutrons which decay into antiprotons and are then trapped by the Earth's magnetic field. Here is a great summary of how this all works.

• There was a nice summary article on recent advances in using DNA to trace the history of humans. One of the most interesting results is that people of European and Asian descent may owe up to 4% of their DNA to Neanderthals. This interbreeding occurred around 65,000 to 90,000 years ago, about the same time when humans began migrating out of Africa. The breadth of information that can be inferred from genetics is pretty astonishing!

• Finally, there was a bunch of excitement today about an extrasolar planet that reflects almost no light. The planet was discovered by the Kepler satellite, which monitors a few tens of thousands of stars, looking for planets to cross in front of them. In this particular case, as the planet passed behind its parent star, astronomers could infer how much light it was reflecting and found only about one percent. This is crazy because even Mercury reflects like ten percent of the light that hits it. One explanation that is being discussed is that the planet's clouds (it's a gas giant like Jupiter) have a weird composition. It's amazing to imagine a planet that is basically a "near-black ball of gas, with a slight glowing red tinge to it."

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