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Planetary News: Asteroids and Comets (2002)Your Chance to See a NEO!2 August 2002Amateur astronomers take note: this may be the best chance you are ever going to have to actually SEE a Near Earth Object! In the middle of August an asteroid of about 800 meters (2500 feet) in diameter will be passing outside the Moon's orbit. Unlike most asteroids and NEOs, it will be bright enough to be observed with amateur telescopes. The asteroid that will be swooping by us was discovered on July 14 by the LINEAR 1 meter (3 foot) telescope in Socorro, New Mexico, and designated 2002 NY40. Right now it is extremely faint, and can only be observed with large professional telescopes. But over the next two weeks it will move closer and gain steadily in brightness, until on the night of the 17th-18th of August it will pass within 530,000 kilometers (330,000 miles) of Earth. At that point it will reach a brightness magnitude of around 9, making it clearly visible with small telescopes, and even binoculars. The brightest stars in the night sky are of magnitude "0", and the faintest objects visible to the naked eye are magnitude 6. Asteroids, according to Don Yeomans, manager of NASA's NEO program at JPL, are notoriously difficult to see "because they're mostly black like charcoal. The most common ones - carbon-rich C-type asteroids - reflect only 3-5% of the light that hits them. Metallic asteroids, which are somewhat rare, reflect 10-15%." This makes this opportunity to observe an asteroid go by truly unique. 2002 NY40 will not only be unusually bright, it will also be moving very rapidly - about 8 degree every hour during its closest pass. With a good telescope, says Dr. Daniel Durda of the Southwest Research Institute in Boulder, Colorado, one will actually be able to watch the asteroid move through the skies, from the constellation Lyra to Hercules. After the asteroid has passed by the Earth, its brightness will drop off quickly and dramatically. Within 24 hours of its passage, it will drop to magnitude 21, and will become practically invisible to most amateurs. This quick disappearing act is not caused so much by the increasing distance of the object, as by its position relative to the Sun when observed from Earth. Right now it is pointing its illuminated side towards us - like a full Moon - making it relatively bright. After it zooms by us, it will come between the Earth and the Sun, and show us only its dark side, just like a new Moon. On the night of August 17th-18th many of us will be in bed, secure in the thought that there are 530,000 kilometers between us and a deadly asteroid impact. Some of us, however, will be up and heading for the hills with their telescopes and binoculars to watch a NEO go by. It is, after all, the chance of a lifetime. |
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