Arecibo Observatory took radar images of asteroid 1998 QE2 and its moon as the space rock sailed safely past earth. The sequence of images show a dark, cratered asteroid 3.0 kilometers across (1.9 miles) across with a companion moon about 750 meters (2500 feet) in size. Both the asteroid and its moon passed 6 million kilometers (3.8 million miles) from earth. This object has no chance of hitting the Earth, but comes close enough to study with a variety of telescopes, large and small.
Figure 1. Radar images of asteroid 1998 QE2 (bottom) and its satellite (top) on June 6. Each image is a sum of 4, spaced apart by about 10 minutes. Each vertical pixel corresponds to 7.5 meters (25 feet) in range, while horizontal pixels correspond to 0.075 Hz (Doppler shift due to rotation).
Figure 2. Radar image from June 7 (left) and from June 9 (right) showing the satellite moving past the primary. Orbital period is about 32 hours.
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