NASA takes radar images of stadium-sized asteroid passing by Earth

NASA's Deep Space Network radar system captured images of an asteroid that made a close approach to Earth.

The day before asteroid 2008 OS7 made its close approach with Earth on Feb. 2. (NASA/JPL-Caltech)

NASA on Monday released radar images of the stadium-sized asteroid from when it made a close approach to Earth.

The slowly-spinning asteroid 2008 OS7 made a flyby past Earth on February 2 and the image was gathered by the space agency’s Deep Space Network planetary radar. It drifted by at a safe distance of about 2.9 million kilometres away from us, which is more than seven times the distance between the Earth and the Moon. It poses no threat to the planet.

The asteroid was originally discovered on July 30, 2009 during routine search operations for near-Earth objects but the NASA-funded Catalina Sky Survey. After it was discovered, the amount of light reflected by the asteroid gave a clue about its size — it was estimated to be between 200 and 500 metres wide, rotating once ever 29 and a half hours.

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But on the February 2 approach, NASA’s Jet Propulsion Laboratory’s radar group used its powerful 70-metre Goldstone Solar System Radar antenna dish at the Deep Space Network’s facility near Barstow. Scientists found that its surface has a mix of rounded and more angular regions. It was also smaller than was estimated previously — about 150 to 200 metres wide.