NASA's Deep Space Network antenna has captured new radar images of Asteroid 2005 YU55 as it approaches Earth in what's set to be the closest approach of a big asteroid ever recorded.
The asteroid will fly past Earth within the moon's orbit today. NASA's been tracking it since November 4, using the 230-foot-wide Deep Space Network antenna at Goldstone, California.
This image was taken yesterday at 11:45 a.m. PST, when the asteroid was approximately 860,000 miles from Earth. The Deep Space Antenna will track it for four hours today, and radar observations from the Arecibo Planetary Radar Facility in Puerto Rico will also begin today.
The 1,300-foot asteroid will make its closest approach to Earth at 3:28 pm PST today.It will come as close as 201,700 miles from the center of the Earth, or about 0.85 times the distance from the moon to Earth.
It's roughly spherical, almost black, and should be visible to sky-gazers with a six-inch telescope.
Although the asteroid's orbit regularly brings it to the vicinity of Earth, Venus and Mars, the 2011 encounter with Earth is the closest it has come for at least the last 200 years.
NASA's keen to reassure the public that its gravitational influence will have no detectable effect on Earth - so no earthquakes or tsunamis.
The last time an asteroid this large came as close to Earth as this was in 1976 - although astronomers didn't know about it until afterwards. The next known approach of an asteroid this size will be in 2028.