View Full Version : The Woman Who Reinvented the Moon

11-10-2018, 05:53 PM
Sarah Stewart
Credit: John D. & Catherine T. MacArthur Foundation

Sarah Stewart is living her ideal life—and it just got sweeter. The University of California, Davis planetary physicist recently won a MacArthur Foundation Fellowship, famously and unofficially known as the “genius grant,” for her work on the origin of Earth’s moon, upending a decades-old theory. She’s been awarded $625,000.

“It’s an amazing concept to just say, ‘We’re going to give you the opportunity to do something, and we’re not going to tell you anything about what to do.’ That’s very unusual and freeing,” she told Nautilus, referring to the grant program. She was particularly thrilled by the recognition the award represents. The foundation speaks to several dozen of a candidate’s peers as a part of its vetting process. “What I really feel is appreciation for my colleagues,” she said. “That really touches me.”


Next year, 2019, is the 50th anniversary of the Apollo moon landing. The rock samples that the Apollo missions brought back basically threw out every previous idea for the origin of the moon. Before the Apollo results were in, a Russian astronomer named Viktor Safronov had been developing models of how planets grow. He found that they grow into these sub- or proto-planet-size bodies that would then collide. A couple of different groups then independently proposed that a giant impact made a disc around the Earth that the moon accreted from. Over the past 50 years, that model became quantitative, predictive. Simulations showed that the moon should be made primarily out of the object that struck the proto-Earth. But the Apollo mission found that the moon is practically a twin of the Earth, particularly its mantle, in major elements and in isotopic ratios: The different weight elements are like fingerprints, present in the same abundances. Every single small asteroid and planet in the solar system has a different fingerprint, except the Earth and the moon. So the giant impact hypothesis was wrong. It’s a lesson in how science works—the giant impact hypothesis hung on for so long because there was no alternative model that hadn’t already been disproven.


The Woman Who Reinvented the Moon (LINK) (http://m.nautil.us/issue/66/clockwork/the-woman-who-reinvented-the-moon)

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Flying Orca
11-10-2018, 06:12 PM
That's really cool.