Close Encounter with Asteroid 2005 YU55 November 8, 2011


Home / Close Encounter with Asteroid 2005 YU55 November 8, 2011

Trajectory of asteroid 2005 YU55 – Image credit: NASA/JPL-Caltech

On November 8, 2011, the small near-Earth asteroid, 2005 YU55, will pass within about 85% of the distance between Earth and Moon from Earth. At its closest approach, asteroid 2005 YU55will be about 325,000 kilometers (202,000 miles) from Earth’s center.

Asteroid 2005 YU55: The Approach

This approach is quite close by astronomical standards, but the asteroid is still far enough away from Earth that there is absolutely no danger whatsoever to Earth from this asteroid. The orbital path of asteroid 2005 YU55 has been accurately calculated by NASAfor the next century, and there is no danger that it will strike Earth during that time. That’s good news, because, according to an article in the November 2011 issue of Sky and Telescope magazine (p53), if this asteroid were to strike Earth, the impact would be very roughly equivalent to about 100 of the largest hydrogen bombs.

During its closest approach, asteroid 2005 YU55 will pass through the constellation Pegasus. It will be about 50 to 100 times too faint to be visible with the naked eye. The asteroid will, however, be visible to amateur astronomers with moderately large telescopes. The November 2011 Sky and Telescope article also has a finding chart to allow stargazers with telescopes to locate 2005 YU55. The asteroid will differ from faint stars in the same field of view because it will be visibly moving across the telescope field.  Astronomers specializing in asteroids plan to observe 2005 YU55 during its closest approach with radar, optical, and infrared wavelengths.

How Big is Asteroid 2005 YU55?

An Arecibo Observatory Radar Image of Asteroid 2005 YU55 – Image Credit: Arecibo Observatory/Mike Nolan

Asteroid 2005 YU55 is about 400 meters in diameter, which is the distance for one lap around a typical track. It is very close to being spherical in shape, which is very unusual for an asteroid – most asteroids have very irregular shapes. The surface of asteroid 2005 YU55is carbonaceous, which means that it contains large amounts of carbon, and carbon-containing compounds.

What Are Asteroids?

Asteroids, also called minor planets, are small pieces of debris left over from the solar system’s origin. They can have either rocky or metallic compositions. Asteroids range in size from about 100 meters (Anything smaller would be classified as a meteoroid.) to about 950 kilometers, the diameter of the largest asteroid, Ceres.

Most asteroids are in the asteroid belt between Jupiter and Mars. There are, however, many asteroids outside the asteroid belt. Earth-crossing asteroids have orbits that cross Earth’s orbit and take them closer to the Sun than Earth. A few asteroids even approach the Sun as close as Mercury’s orbit.

If they could be mined or brought to Earth, metallic asteroids could be quite valuable. The minerals in a typical metallic asteroid that is a few kilometers in diameter would be worth trillions of dollars at current market prices.

Meaning of the Name Asteroid 2005 YU55

Asteroid 2005 YU55 will pass through Pegasus – Image credit: Roberto Mura

The discoverer of an asteroid traditionally has the right to name it, subject to approval by the International Astronomical Union (IAU). All asteroids are, however, given a preliminary designation. the preliminary designation 2005 YU55 indicates that the asteroid was discovered in 2005. The Y indicates that it was discovered in the second half of December, and the U55is a code indicating the order in which the asteroid was discovered during the second half of December.

Benefits of a Fly-By Asteroid

Asteroid 2005 YU55 presents astronomers a unique opportunity to study an asteroid close up without needing to send an expensive space probe. It will, therefore, greatly increase astronomers’ understanding of asteroids, while presenting absolutely no danger to Earth.

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