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The famous Arecibo Observatory in Puerto Rico completely collapsed in 2020. Now, scientists going through its final observations offer a major new asteroid report...Using data collected by Arecibo between December 2017 and December 2019, scientists have released the largest radar-based report on near-Earth asteroids ever published. The report, published Sept. 22 in The Planetary Science Journal, includes detailed observations of 191 near-Earth asteroids, including nearly 70 that are deemed "potentially hazardous" — that is, large asteroids with orbits that bring them within 4.65 million miles (7.5 million kilometers) of Earth, or roughly 20 times the average distance between Earth and...

The bouncing-baby asteroids were revealed by three radar telescopes, which shoot a beam of radio waves at nearby asteroids and wait for the reflection to return to Earth. Astronomers can use those received signals to paint a picture of the shape of an asteroid. In this case, that meant discovering that what looked like two lobes of one rock are actually two separate rocks, circling each other every 20 to 24 hours. It's a particularly exciting surprise because the two pieces of 2017 YE5 are almost the same size, each about 3,000 feet (900 meters) across. So far, scientists have...