Tomorrow evening (Tuesday, Nov. 8) at about 6:28, a space rock a little over 1,300 feet in diameter will pass within about 202,000 miles of Earth. It will not hit our home planet nor will it have any other effect on us; it's just passin' through. Designated 2005 YU55, it is a potentially hazardous asteroid because of its size and near-Earth orbit. It was discovered on December 28, 2005 by Robert S. McMillan at Steward Observatory, Kitt Peak, Ariz.
The main reason the flyby is known to the public is that this large asteroid will be closer to us than is our own Moon and that's a neat science headline. When big asteroids --chunks of rock moving through space-- come close to Earth, news of the event has different effects in different quarters.
Amongst astronomers asteroid fly-bys offer an excellent opportunity to study small "worlds" usually too far away to see clearly with telescopes. NASA and other agencies are already scanning the space rock with high-powered radar systems in an effort to learn more about the object. The data can be used to learn something about the texture and composition of the object and a bit about its history. The asteroid's orbit will also be highly refined through tracking by observers from around the world allowing improved prediction of its future movements.
Amongst conspiracy and doomsday fanatics, the close passage is another opportunity to spread FUD (Fear, Uncertainty, and Doubt) through pseudoscience and false prophesy. The Web is abuzz with gloom, doom, and gobs of misinformation already. What will they be saying Wednesday morning after 2005 YU55 has floated clean by Earth and left us unscathed?
Here are some facts about our visitor from space and asteroids in general:
- The word asteroid literally means "star-like object."
- Asteroids come in sizes ranging from small stones to a body about 3,300 feet in diameter: Ceres, the largest known object of that type.
- The last time a space rock as large as 2005 YU55 came as close to Earth was in 1976, although astronomers did not know about the fly-by at the time. The next known approach of an asteroid this size will be in 2028.
- Asteroid 2005 YU55 will pass through the constellations Aquila and Pegasus glowing like an 11th magnitude star (very dim) when closest, not visible to the unaided eye. You'd need a good-sized telescope and clear dark skies to see the tiny star-like object.
- This asteroid orbits the Sun, roughly as close as Venus to as far away as Mars. Along the way it crosses Earth's orbital path, one factor that makes it potentially hazardous.
- Large asteroids pass closer to Earth than the Moon about every five years; smaller ones pass close more frequently and often enter Earth's atmosphere.
- Asteroids nearly the size of a house collide with Earth about once a year with no harmful effects to us -- they ordinarily explode in the upper atmosphere and the fragments burn up.
- Though a good-sized ball of rock, 2005 YU55 does not have enough mass to have any gravitational effect on Earth.
- Asteroid close-encounters do not cause earthquakes, high tides, or any other geological or weather events.
- Asteroids are cataloged, their orbits calculated, and the objects tracked regularly both for scientific study and planetary protection ends. Those data are publicly available and often incorporated into home astronomy software.
- The approach of asteroids cannot be kept secret. They are "out there" and visible to all who care to look. Any truly dangerous situation would quickly be confirmed by scientific authorities from around the world.
Asteroids are but one small part of our fascinating solar system. Follow the news, read up on astronomy here at the library -- the pictures are great, too -- and enjoy the real adventure!