A census of the moon’s craters is helping scientists decipher its history.
Ever since Galileo first trained his telescope on the moon in the 17th century, astronomers have wanted to know more about its craters: How many pit its surface? How big are they? And how did they form? Answers came flooding in when NASA’s Lunar Reconnaissance Orbiter (LRO) began circling the moon in 2009. A laser-ranging instrument aboard the spacecraft mapped the moon’s topography in high definition, revealing the location of more than 5,000 craters over 12 miles in diameter, and countless others smaller in size. Researchers found the distribution of large and small craters varies, with more big craters covering the moon’s bright highlands, and more small craters dotting the dark lowlands. The results suggest two distinct populations of impactors pummeled the moon over the past 4.5 billion years. Watch the video to see a color-coded map of lunar craters created from LRO data.