Asteroid 2005 YU55 - Credit NASA/Cornell/Arecibo
Asteroid 2005 YU55 - Radar image taken in 2010 - Credit NASA/Cornell/Arecibo

On November 8th at 3:28 PM PST the asteroid “2005 YU55” will pass by the Earth at a distance of just over 200,000 miles, or about 40,000 miles within the Moon’s orbit. This is a relatively close pass for an asteroid, like a football-stadium-sized football making a field goal through the posts of the Earth and the Moon. Fortunately for us, there will be no touchdown….

At about 1,300 feet across, this roughly spherical, charcoal-black space rock would give us quite a wallop if it were to hit the Earth. A bit larger than a typical football stadium (including a bit of the parking lot), if this asteroid were to strike Earth’s ocean a powerful tsunami result, and if it struck land, a city-sized hole in the ground. Not to mention a lot of fireworks.

Fortunately, the asteroid’s trajectory is well known, and poses no threat to us (at this time).

Asteroids and comets that can come close to the Earth—Near Earth Objects, or NEOs—have been a concern to life on Earth since it began. From the end of the “era of heavy bombardment,” when the young Earth endured frequent impacts by asteroids and comets, large and small, debris leftover from the formation of our Solar System still meets up on occasion with our planet. Craters from past large impacts can be found today, camouflaged by millennia or eons of erosion, sedimentation, and tectonic activity—Earth’s scar-healing processes.

The crater left by a 10-mile-sized asteroid (that would be the stadium, parking lot, and the surrounding major metropolitan area) believed to have contributed to the demise of the dinosaurs lies hidden and buried at the tip of the Yucatan Peninsula: the Chicxulub crater. (No, Chicxulub is not an all-women car service station….) Other craters masquerade as round lakes and other landscape sculptures.

And some are quite candidly impact craters, like “Meteor Crater” near Winslow Arizona. When I was in the Peace Corps in Cameroon, my house was 2 kilometers from a round lake that is apparently a meteorite crater. (That’s Lake Ejagham; check it out at 5.750000 degrees north latitude and 8.987778 degrees east longitude.) Lake Ejagham is about a kilometer in diameter and 60 meters deep (not counting sediment infill). The meteorite that created it wasn’t nearly that big—probably the size of a very small house….

Now imagine an object the size of asteroid 2005 YU55 striking Earth, land or sea. It wouldn’t cause our demise—except for unfortunate bystanders—but it would create havoc around ground zero.

And even though 2005 YU55 will not hit the Earth on November 8, all NEOs that pass that close (within the Moon’s orbit) are considered near misses, and are scrutinized by the “eyes of the Earth”: radio dishes and optical telescopes across the planet.

Chabot’s own NEO observing team will aim the eye of our 36-inch telescope, Nellie, on the asteroid and measure its trajectory, contributing to our knowledge of this particular NEO’s orbit and improving our ability to predict its future passes.

This time, it’s a mere field goal.

Asteroid 2005 YU55 Scores! 12 June,2013Ben Burress


Ben Burress

Benjamin Burress has been a staff astronomer at Chabot Space & Science Center since July 1999. He graduated from Sonoma State University in 1985 with a bachelor’s degree in physics (and minor in astronomy), after which he signed on for a two-year stint in the Peace Corps, where he taught physics and mathematics in the African nation of Cameroon. From 1989-96 he served on the crew of NASA’s Kuiper Airborne Observatory at Ames Research Center in Mountain View, CA. From 1996-99, he was Head Observer at the Naval Prototype Optical Interferometer program at Lowell Observatory in Flagstaff, AZ.

Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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