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It's Amateur Night in Space

Comet C/1999 S4, taken by Charles S. Morris on July 4, 2000
Image courtesy: Charles S. Morris

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Near-Earth Object site
Comet Observation site
Go to flash -- Keeping an Eye on Space Rocks
How would you like to discover a near-Earth object without leaving your own backyard? It's possible. On July 2, 2000, amateur astronomer and public schoolteacher Leonard L. Amburgey stumbled upon the near-Earth asteroid 2000 NM using a modest telescope in his backyard in Fitchburg, Mass. Amburgey became the fourth winner of the James Benson Prize for Discovery Methods of Near-Earth Objects by Amateurs. The first amateur to win the cash prize was Arizona resident Roy Tucker, who found an Earth-orbit crossing asteroid from his backyard using a Celestron 14-inch telescope and a self-designed camera.

"There are some very sophisticated amateur astronomers out there and we rely upon them to help monitor the future motions of Earth-approaching comets and asteroids," said Dr. Don Yeomans, JPL manager of NASA's Near-Earth Object Program Office.

Amateur astronomers are making a big difference in helping NASA keep an eye on the comets and asteroids that can get close to Earth. While NASA-supported professional astronomers discover the vast majority of near-Earth asteroids, amateur astronomers provide many of the follow-up observations needed to pinpoint the orbits and predict the future motions of the asteroids. Once a new near-Earth asteroid is discovered, the efficiency with which amateurs provide these follow-up observations allows larger professional telescope facilities to continue scanning the skies for more new discoveries.

The study of near-Earth objects is not only important for monitoring Earth-threatening objects, but also for understanding how the solar system formed from these bodies. Comets are the leftover bits and pieces from the formation of the outer solar system, which occurred some 4.6 billion years ago. Asteroids are the debris left from the inner solar system formation process. Comets and asteroids are also important because they brought to the early Earth some of the water and carbon-based molecules from which life formed.

But how does one discover a near-Earth object?

The most successful near-Earth object hunters are those who can scan large areas of dark sky each night with large aperture telescopes. Some amateur astronomers, like Bill Yeung, are able to set up their own private observatories. Yeung, who discovered his first 15 asteroids by renting a 16" telescope that was a 2-hour drive away from his home in Canada, now observes the sky with several powerful telescopes running each night at his Desert Eagle Observatory in Benson, Ariz. He has made 1732 asteroid discoveries, including the object recently identified as J002E3 that turned out to be an Apollo 12 rocket stage. This discovery is highlighted on the JPL Near-Earth Object Program Office Web page at: http://neo.jpl.nasa.gov.

Most asteroids are discovered when their motions, relative to the fixed background of stars, give them away. Professional telescopic surveys can capture images of a particular region of sky three or more times several minutes apart. These images are compared to see if any bright "stars" are actually moving, revealing them as potential near-Earth objects. Amateur astronomers study the variations in the amount of sunlight that asteroids reflect as they rotate in space. Based on these observations, astronomers can determine the asteroid's rotation period and often the orientation of its rotation axis in space. They can also infer certain characteristics of the asteroid, such as its size and shape.

Amateur astronomers are particularly adept at discovering comets. Comets appear fuzzy when their ices vaporize near the Sun, releasing dust particles that reflect sunlight. Amateur astronomers have been very successful in discovering some of the brighter comets by scanning the skies for fuzzy bright spots in the twilight and pre-dawn skies. The most recent impressive comet (Hale-Bopp), seen in the spring of 1997, was discovered by two amateur astronomers, Alan Hale and Thomas Bopp.

A bright comet zooms toward the Sun while two coronal mass ejections (huge bubbles of gas ejected from the Sun) head for Earth. In these SOHO images taken on October 24, 2001, the shaded disk represents a mask in the viewing instrument that blots out direct sunlight. The white circle in the disk shows the size and position of the visible Sun.

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SOHO site

One area where amateur astronomers have outdone the professionals is in discovering near-Sun comets. Using digital images of a region of space near the Sun provided in near-real time on the Internet by the Solar and Heliospheric Observatory project, amateur astronomers have actually identified several hundred "kamikaze" comets. These tiny icy comets, most of which are fragments from a once larger comet, destroy themselves as they plunge toward the solar inferno.

What do I do if I find a near-Earth object?

Should an amateur astronomer make an asteroid or comet finding, they should contact the Minor Planet Center, part of the Smithsonian Astrophysical Observatory at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. The Minor Planet Center makes the observations provided by the entire international astronomical community available to other orbit determination centers such as JPL's Near-Earth Object Program Office. Using these observations, professional astronomers can compute the near-Earth object's orbit and predict its future motion.

The purpose of the Near-Earth Object Program is to coordinate NASA-sponsored efforts to detect, track and characterize potentially hazardous asteroids and comets that could approach the Earth. The program will focus on the goal of locating at least 90 percent of the estimated 1,000 asteroids that approach the Earth and are larger than 1 kilometer (about two-thirds of a mile) in diameter, by the end of 2008. In addition to helping coordinate the detection and cataloging of near-Earth objects, the Near-Earth Object Program Office will be responsible for facilitating communications between the astronomical community and the public should any potentially hazardous objects be discovered.

JPL is a division of the California Institute of Technology in Pasadena, California.

October 28, 2002

Contact: JPL/Charli Schuler (818) 354-3965

NASA's Jet Propulsion Laboratory