Online Spacewatch Volunteer Discovers Close-Approaching Asteroid(Forwarded)

News Services
University of Arizona
Tucson, Arizona

Contact Information:
Robert S. McMillan, 520-621-6968,
Stu Megan,

January 21, 2004

Online Spacewatch Volunteer Discovers Close-Approaching Asteroid
By Lori Stiles

A volunteer who analyzes online images for the University of Arizona Spacewatch
program has discovered a 60-to-120-foot diameter asteroid that will miss Earth
by about 1.2 million miles tomorrow, Jan. 22.

While the asteroid is no cause for alarm, its discovery marks a milestone in a
new project that relies on volunteers to spot fast-moving objects, or FMOs, in
Spacewatch images.

Even if asteroid 2004 BV18 hit Earth head-on, it would only create a bright
flash of light in the upper atmosphere, and possibly streaks of light as
asteroid fragments heat to incandescence while they rocket across the sky. "In
other words, a bright meteoric display known as a bolide," said Robert S.
McMillan, who directs UA's Spacewatch.

The asteroid appeared in images taken by Spacewatch astronomer Miwa Block with
the 0.9-meter telescope at 1:49 UT on Jan. 19, which is 6:49 p.m. MST on Jan.
18. Volunteer Stu Megan reviewed the images on the Internet, and spotted the
asteroid's light trail. Megan is part of a Web-based program that Spacewatch
made public last October through a grant from the Paul G. Allen Charitable
Foundation.

"It's hard to explain the excitement when you find a fast-moving asteroid,"
Megan said in an E-mail message.

Megan is semi-retired from a 35-year career in information technology and an
amateur astronomer who is interested in finding potentially hazardous asteroids.
A resident of Tucson, he has reviewed close to 6,500 Spacewatch images during
the past three months.

"When I saw (this light trail), it just sat there screaming at me. It was very,
very bright and a perfect length. I knew it could be nothing else."

Three observatories made follow-up observations of the asteroid, so scientists
at the Minor Planet Center could compute its orbit. The Minor Planet Center gave
Asteroid 2004 BV18 its provisional designation yesterday. (A provisional
designation is one that's adopted until the asteroid's orbit is known well
enough that astronomers won't lose it.) The center also published the discovery
and follow-up studies in the Minor Planet Electronic Circular yesterday.

The asteroid is classified as an "Apollo" asteroid because it is on average
slightly farther from the sun than the Earth is, but its modest orbital
eccentricity causes it to occasionally cross Earth's orbit.

At the time Megan discovered the asteroid, it was six times farther from Earth
than the Earth is from the moon. Seen from Earth, it appeared to move across the
sky at about 6.5 degrees per day, or about the diameter of 13 full moons. At
closest approach tomorrow, it will be five times the distance between Earth and
the moon.

Spacewatch operates 1.8-meter and 0.9-meter CCD-equipped telescopes on Kitt
Peak, about 45 miles southwest of Tucson, Ariz. The project studies solar system
dynamics through the movements of asteroids and comets. Spacewatch also finds
potential targets for interplanetary spacecraft missions and hunts for objects
that might pose a threat to Earth.

The 0.9-meter telescope typically takes two-minute-long exposures, and objects
closest to Earth move so quickly through the telescope's field of view that they
trace a line on the sky image. Objects orbiting farther from Earth appear to
move more slowly, just as an airplane flying at 40,000 feet appears to move
slower than it does at takeoff.

Computer software has a hard time detecting FMO light trails because they vary
greatly in length and direction.

Human observers are still much better than computers at finding FMOs in
Spacewatch images. But the work is too time intensive for on-duty Spacewatch
observers. So the astronomers have turned to 30 volunteers for help. FMO project
volunteers are based in the United States, Germany, and Finland.

They would gladly accept more.

The only requirements are interest, sharp eyes, and access to a computer when
astronomers are operating Spacewatch telescopes on Kitt Peak. More details on
how to volunteer for the FMO Project are on the Web at FMO Project.

"Our reviewers are students, people with full-time jobs, retired -- they run the
gamut," McMillan said. "While our most dedicated volunteers tend to be members
of the amateur astronomy community or at least have a strong interest and
knowledge of astronomy, we have members who have just begun to climb the
learning curve.

"We hope that our Website helps fuel curiosity and participation in science in
general, as well as provide a productive outlet for those eager to apply their
computer skills," McMillan said.

McMillan's Spacewatch team protects the privacy of its volunteers, releasing
volunteers' names only to the Minor Planet Center when discoveries are to be
published.

Astronomers want to study small asteroids to know how many there are, their spin
rates and surface properties, McMillan said.

Spin rate tells observers if the asteroid is a single solid piece or a loose
aggregate of rocks.

The distribution of asteroid sizes tells scientists about the effects of
asteroid collisions during the lifetime of the solar system.

The smallest asteroids are free of regoliths, the blanket of loose dust or dirt
that obscures the bare rock surfaces of larger asteroids. And the smallest
asteroids are useful for studying non-gravitational forces that work on very
long time scales, such as the Yarkovsky Effect, a phenomenon where heat propels
objects through space.

The Spacewatch Project was begun in 1980 at the UA Lunar and Planetary
Laboratory. More information about Spacewatch can be found on the Web at Spacewatch.

Related Web sites

* Spacewatch
http://spacewatch.lpl.arizona.edu/
* FMO Project
http://fmo.lpl.arizona.edu/FMO_home/index.cfm

[NOTE: Images supporting this release are available at
http://uanews.opi.arizona.edu/cgi-bi...rticleID=8492]