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Emily Lakdawalla • Jan 28, 2008

Asteroid near misses are disconcertingly common

I've been investigating some of the recent excitement about dangers from the skies, and particularly asteroid 2007 TU24, which will pass harmlessly by Earth tonight, considerably farther from Earth than the Moon. Here's some recent radar images of the near-Earth object, which is roughly 250 meters in diameter.

Near-Earth asteroid 2007 TU24

NASA/JPL-Caltech

Near-Earth asteroid 2007 TU24
This low-resolution radar image of near-Earth asteroid 2007 TU24 was captured from the Goldstone radio telescope in the Mojave desert. It shows an irregularly-shaped asteroid roughly 250 meters across. TU24 will pass within 1.4 lunar distances, or 538,000 kilometers (334,000 miles), of Earth on Jan. 29 at 08:33 UTC (12:33 a.m. PST).
Itokawa rotates under Hayabusa

ISAS / JAXA / Øyvind Guldbrandsen

Itokawa rotates under Hayabusa
This animation consists of 57 separate images captured by the Hayabusa spacecraft as the tiny asteroid Itokawa (535 by 294 by 209 meters in size) rotated underneath it. The images are actually from three separate rotations; they were sorted and lined up into this animation by Øyvind Guldbrandsen of the Norwegian Astronautical Society. Click here for a full-resolution movie containing 169 frames (AVI format, 3.8 MB)

Astronomers are more excited about TU24's size than its miss distance. It'll pass by at about 1.4 lunar distances, which is really pretty far away (the Moon is about 30 earth diameters away, so the asteroid will miss us by a distance that is 40 or 50 times our diameter -- that's pretty far). This image from MESSENGER's Earth flyby illustrates that separation: 1.4 lunar distances is not even close.

The Earth and Moon as seen by MESSENGER

NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The Earth and Moon as seen by MESSENGER
This image was cropped from the MESSENGER Dual Imaging System (MDIS) full frame of the Earth and Moon captured on May 11, 2005. MESSENGER was about 29.6 million kilometers (18.4 million miles) from Earth at the time that the photo was taken, approaching its August 2 flyby.

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