Asteroids - On the first day of January 1801, Giuseppe Piazzi discovered an object which he first thought was a new comet. But after its orbit was better determined it was clear that it was not a comet but more like a small planet. Piazzi named it Ceres, after the Sicilian goddess of grain. Three other small bodies were discovered in the next few years (Pallas, Vesta, and Juno). By the end of the 19th century there were several hundred. More than 7000 asteroids have been discovered. Several hundred more are discovered each year. Asteroid Introduction - Asteroids are material left over from the formation of the solar system. One theory suggests that they are the remains of a planet that was destroyed in a massive collision long ago. More likely, asteroids are material that never coalesced into a planet. In fact, if the estimated total mass of all asteroids was gathered into a single object, the object would be less than 1,500 kilometers (932 miles) across -- less than half the diameter of our Moon. Interactive Star Atlas     Object Catalogues: Asteroids (by name)     Object Catalogues: Asteroids (by number) Fix: Chapter 15 Solar System Debris IAU: Minor Planet Center operates at the Smithsonian Astrophysical Observatory, under the auspices of Commission 20 of the International Astronomical Union (IAU) and is a nonprofit organization, with principal funding coming from subscriptions to the various services offered by the Center. The MPC is responsible for the efficient collection, (computation,) checking and dissemination of astrometric observations and orbits for minor planets and comets, via the Minor Planet Circulars (issued monthly) and the Minor Planet Electronic Circulars (issued as necessary).     IAU Astronomical Headlines     Recent IAUCs     Recent MPECs     Near-Earth Objects (NEOs)     Orbital Elements     PHA Close Approaches To The Earth     List Of The Potentially Hazardous Asteroids (Orbital Elements)     Calculate Impact Effects Current Impact Risks -- This table lists potential future Earth impact events that the JPL Sentry System has detected based on currently available observations. Click on the object designation to go to a page with full details on that object. Asteroids whose orbits have been determined carefully enough so that their position on the sky as a function of time can be predicted are assigned permanent numbers and names by the Minor Planet Center. At present, there are more than 8,700 numbered asteroids (Minor Planet Center, Schmadel 1997). Astroid names are chosen by the discoverer, and some noteworthy names assigned to asteroids are 3834 Zappafrank, 2906 Caltech, 2404 Antarctica, 5102 Benfranklin, 7850 Buenos Aries, 10221 Kubrick, etc. Iowa's Manson Impact Structure Terrestrial Impact Crater Structures Terrestrial Impact Craters Impact Structures listed by Diameter Close to Eros - A long mosaic was constructed of images returned October 25, 2000 by the NEAR Shoemaker spacecraft as it orbited to within 6.4 kilometers of a spot in the southern hemisphere of the rotating asteroid's surface. That distance (about 21,000 feet) is less than the cruising altitude of most commercial airline flights. The digital images show that while many regions appear smooth with craters filled in by an accumulation of loose regolith, much of Eros' surface is littered with rocks and boulders. The large boulder glinting in the sunlight at the far left, just above the center of the mosaic, spans approximately 25 meters. In the high-resolution view, the smallest rocks visible are roughly human-sized at about 1.4 meters (5 feet) across. The car-sized Near Shoemaker spacecraft is now on its way to a higher, more stable orbit about 200 kilometers above asteroid Eros. Amateur asteroid hunters part of new golden age of astronomy - Amateur astronomers can make an important contribution to asteroid research. Dedicated amateurs make a real contribution to science from their own back yard. NOVA: "The Doomsday Asteroid" - ANNOUNCER: Tonight on NOVA. Massive rocks have pounded the planets for centuries, but humans have never witnessed an actual impact until nearby Jupiter was pummeled. Could it happen here? Could Planet Earth be the next target? Tunguska event - The Tunguska Event, sometimes called the Tunguska explosion, was a massive explosion that occurred near the Podkamennaya (Lower Stony) Tunguska River in what is now Krasnoyarsk Krai of Russia, at around 7:17 a.m. on June 30, 1908     © Copyright 2008 - Samuel J. Wormley   by swormley1@mchsi.com