University of Colorado at Boulder researchers will scientifically analyze a meteorite that fell outside Berthoud, Colo., last week, only the fifth to ever have been seen falling and subsequently recovered in Colorado, experts say.
The meteorite weighs more than 2 pounds and is about as large as a baseball, although it is irregular in shape. It appears to be made of igneous rock and is melted on its surface from the heat of entering the atmosphere. The meteorite probably broke off an asteroid or planetary body.
"Its igneous composition reveals that it was chipped off an asteroid large enough to undergo some form of volcanic activity," said Nick Schneider, associate professor of astrophysical and planetary sciences.
Megan and John Whiteis of Berthoud, and Megan's son, Casper, provided the meteorite to aerospace engineering sciences assistant professor Scott Palo for scientific analysis after they saw it land in their backyard. The couple had just walked out their back door into the yard at 1:30 p.m. on Oct. 5, when the meteorite flew over their heads and landed about 100 feet ahead of them.
Megan's mother, Marilyn Meador, contacted the National Center for Atmospheric Research and spoke with Dr. Maura Hagan who emailed Palo. Palo is an expert in radio meteors -- the study of ionized meteor trails in the upper atmosphere using radio waves. Palo spent the next few days putting together a team of scientists interested in helping to analyze the specimen. The team includes:
* Jack Murphy, curator emeritus of the Denver Museum of Nature and Science, who is writing a book on Colorado meteorites
* Chris Peterson, of Cloudbait Observatory, a Colorado fireball observation network in Guffey, Colo., who is working to reconstruct the trajectory and orbit of the meteorite using infrasound and observations
* Assistant Professor Stephen Mojzsis of the CU-Boulder department of geological sciences
* Associate Professor Nick Schneider of the CU-Boulder department of astrophysical and planetary sciences and the Laboratory for Atmospheric and Space Physics (LASP)
* Doug Duncan, director of Fiske Planetarium
The first scientific test will measure gamma rays being emitted by the meteorite. It is likely the test will be performed at NASA's Johnson Space Center later this week. Because this is a fresh fall, the volatile chemical species can be measured. Analysis of the rare gasses and gamma ray emissions will provide information about the size and history of the meteorite before it entered the Earth's atmosphere.
Analysis of the meteorite trajectory and orbit also will be conducted in an effort to learn where this meteorite originated. Over the past 7 years to 10 years, a surprising number of fireballs have been observed during the first week of October. Scientists have little understanding about the source of the fireballs but the Berthoud meteorite could provide a wealth of information about these recent events. The possibility of tracking a meteorite back to its place of origin in the asteroid belt is a rare opportunity.
Researchers are asking the public to report any fireball sightings in the sky during October in order to help determine the meteorite's trajectory and point of origin. Fireball sightings can be reported by going to www.cloudbait.com.
Residents of Berthoud also are asked to keep their eyes open for any rocks that appear unusual with a smooth, black, shiny crust. People who find objects they think may be a meteorite should contact Jack Murphy at (303) 370-6445.
Discoverers Megan and John Whiteis have expressed their keen interest in making the Berthoud meteorite available for educational purposes. Until needed for scientific analysis, the meteorite will be displayed and discussed in CU classrooms and at Fiske Planetarium. CU faculty will work with local K-12 educators and the discoverers to bring the excitement and importance of the Berthoud meteorite to schools and museums around the state.
Viewing times at Fiske will be posted at www.colorado.edu/fiske and requests for class visits should be made to Suzanne Traub-Metlay at (303) 492-4073.
METEORITE FACT SHEET
CU-Boulder, Oct. 11, 2004
A meteoroid is a small object - generally smaller than the size of a pebble - and usually comes from asteroids, the moon, comets or Mars.
Thousands of meteorites fall to Earth each year. Meteorites generally become visible at about 60 miles from the ground due to the intense heating from striking the atmosphere at speeds of at least 20,000 mph. Only the largest meteors are bright enough to see in the daytime sky.
The average weight of a shooting star, or meteor, in the sky is less than one ounce -- about the size of a pea or smaller. Larger meteors that hit the ground become meteorites by definition. Most meteors decay into dust in the atmosphere and never make contact with Earth's surface.
The largest known meteorite is a 70-ton specimen still embedded in the ground in Grootfontein in southwest Africa. The largest meteorite ever found in the United States is the Willamette meteorite, which was found in Oregon and weighs about 15 tons.
Fireballs are defined as any meteor that is brighter than Venus in the night sky. The appearance of a fireball is often followed by a sonic boom.
A meteorite generally is named for the locale, region or town where it was found.
Meteorites generally are classified into three categories: Stony, iron and stony-iron.
Only about 10 per cent of the meteorites that reach Earth are "iron meteorites." Iron meteorites are rare because they typically become buried upon impact. Of the 75 meteorites that have been recovered in Colorado, 14 are iron.
Stone meteorites can be divided into chondrite and achondrite types. Chondrites contain chondrules, tiny, spherical blobs of silicates from the earliest solar system formation which pre-date planetary formation.
Achondrite meteorites, like the one recently discovered near Berthoud, Colo., make up about 7 percent of all known meteorites. Achondrite meteorites are made from chondritic material that was melted and re-crystalized while still on or within its parent solar system body.
Achondrite meteorites may be pieces of planets and moons ejected during impacts or collisions eons ago and may have traveled through the solar system for millions of years. The now-famous Allan Hills meteorite from Mars was discovered in 1984 in Antarctica and continues to be controversial since some scientists believe it contains microscopic evidence for life.
Editor's Note: A media briefing with photo opportunities will be at 11 a.m. Oct. 11 at the CU-Boulder College of Engineering and Applied Science. Meteorite experts and the individuals who saw the meteorite fall to the ground will be present. The briefing will be in the Bechtel Collaboratory of the Discovery Learning Center, located at the intersection of Colorado Avenue and Regent Drive. Call (303) 492-7426 for further information.