2 Moons Orbit Giant Asteroid That Buzzed Earth (Video)

[Judi Lynn]

By Mike Wall, Space.com Senior Writer | September 8, 2017 06:27pm ET


The huge asteroid that cruised past Earth last week in a record-breaking flyby has two moons, radar images reveal.

On Sept. 1, the 2.8-mile-wide (4.5 kilometers) near-Earth asteroid 3122 Florence zoomed within 4.4 million miles (7 million km) of our planet — a mere 18 times the distance from Earth to the moon. No other space rock that big has come so close since NASA began tracking asteroids in earnest, agency officials have said.

The flyby therefore presented a rare scientific opportunity, and astronomers around the world trained a number of instruments on Florence as it approached. One such facility was NASA's Goldstone Deep Space Communications Complex in California, which captured some dramatic and informative views. [Famous Asteroid Rock Flybys and Close Calls (Infographic)]

For example, imagery obtained by the 230-foot (70 m) dish at Goldstone confirmed Florence's size and its 2.4-hour rotation period, values that scientists had already figured out thanks to previous observations. And Goldstone revealed that the asteroid is roughly spherical, with an equatorial ridge and at least one big crater, NASA researchers said.

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