「首发」沃邦名师3月10日亚太SAT考试考情速递(17)

“We’re realizingthat the early moon was a much more dynamic place than we thought,” saysJeffrey Andrews-Hanna, a planetary scientist at the Colorado School of Mines inGolden and lead author of a new study of the Procellarum’s geology. Thediscovery also casts doubt on the decades-old theory that the circularProcellarum region is a basin, or giant crater, created when a large asteroidslammed into the moon. “We don’t expect a basin rim to have corners,”Andrews-Hanna says.
The work isbased on data gathered by GRAIL (Gravity Recovery and Interior Laboratory), apair of NASA spacecraft that orbited the moon in 2012. Sensitive to tinyvariations in the gravitational tug of the moon, GRAIL mapped densityvariations below the surface (because regions of higher density produceslightly higher gravitational forces). Below known impact basins, GRAIL foundthe expected ringlike patterns, but underneath the Procellarum region, themysterious rectangle emerged. “It was a striking pattern that demanded anexplanation,” Andrews-Hanna says.