How the moon was made

How the moon was made

People always wonder how the moon was made. The birth of the planets 4.5 billion years ago was extremely violent. They grew to full size by absorbing rival planet embryos in a series of titanic collisions—one of which probably gave Earth its moon (below). The moon’s large size, low density, and other features suggest that it emerged from an explosion […]

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Our sun’s hotter sister

Stars are not born alone. Rather, they emerge from clouds of gas and dust in groups of up to 10,000, then slowly scatter through space. For the first time, astronomers have identified a star that came from the same solar nursery as our sun, some 4.5 billion years ago. This stellar relative—located 110 light-years away in the constellation Hercules—is hotter […]

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Earth’s bigger, older cousins

Astronomers have discovered the larg­est rocky planet yet, and its existence has profound implications for our understanding of the early universe and the potential for extraterrestrial life. Kepler-10c, which was spotted by NASA’s Kepler space telescope, has a diameter of roughly 18,000 miles—more than twice that of Earth —prompting scientists to create a new class of planets, dubbed “mega-Earths.”The body’s […]

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The Sun Is Coming!

Earth got off relatively easy last week after being hit by the biggest blast of solar radiation since 2005—but we may not be so lucky next time. Last week’s coronal mass ejection, in which a solar flare whipped an arc of magnetic particles toward Earth at 4 million mph, led some airlines to reroute flights away from the poles, where […]

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