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'Green Flash' Was Really 2, Experts Say

Astronomy: Meteor was seen over New Mexico 100 minutes before it was sighted in L.A.

October 15, 1996|THOMAS H. MAUGH II | TIMES STAFF WRITER

The meteor that caused a green flash over the Southland in the early evening of Oct. 3 apparently streaked through the sky above New Mexico 100 minutes earlier, then circled Earth before reaching the ground north of Kernville, UCLA researchers said Monday.

Intrigued by this unusual event, the UCLA team is offering a $5,000 reward for the first person who finds a piece of the meteorite weighing more than 4 ounces.

The bright green flash, which was widely reported in the Los Angeles area, stirred a great deal of interest and speculation about its origin, in part because some sightings were as far as New Mexico. But UCLA's John Wasson, a cosmochemist who is a meteorite specialist, was skeptical about some of the reports.

Because of the Earth's curvature, to be seen from New Mexico, the Los Angeles-area meteor must have been more than 100 miles above California, Wasson said. But meteors do not encounter enough atmosphere to be visible--what we see is the glow of the speeding space rock burning up as it contacts air--until they are below 100 miles.

"They couldn't have seen [the same meteor] there," he said of people in Albuquerque.

Or did they?

Meteor researcher Mark Boslough of the Sandia National Laboratories in Albuquerque, who investigated the New Mexico sighting, found that residents there had indeed seen a green flash, heading in an east-northeasterly direction, at 8:04 p.m. Mountain Daylight Time.

That report was itself unusual though. Most meteors brighten as they pass through the sky, often disappearing in a bright flash. The New Mexico meteor, however, brightened, then dimmed--as would be expected if it were just skipping briefly through the atmosphere.

At UCLA, a reconstruction by Wasson and Lori Leshin found that the meteor flashed through Southland skies 100 minutes later, at 8:44 PDT. One hundred minutes is the time required for an object in low Earth orbit to make one circuit.

The rock from space, which Wasson estimates weighed at least 2.2 pounds, passed over the California coast north of Santa Barbara also traveling east-northeast, the researchers concluded. They think it traveled north of Bakersfield and disappeared in the Sequoia National Forest north of Kernville.

Its disappearance from the sky was noted by a group of students and teachers from Flintridge Preparatory School in La Canada, who were camping along Lower Peppermint Creek in the forest.

The meteor's latitude over California was the same as it was over New Mexico, a necessary condition if it had been in orbit, Wasson said.

Finally, he noted, the longitudinal distance between the two sightings was 25 degrees, the amount Earth turns on its axis in 100 minutes.

"We can't be 100% certain that it was the same object, but there are too many similarities for it to be a coincidence," he said.

Wasson doesn't know for certain that the rock reached the ground. If it did, however, he and his colleagues would like to see it--so much so that they have pooled their resources to offer the reward.

Pieces from the meteorite could have fallen anywhere along the ground track of the object, he said. They would probably be about the size of a pea or a grape and have a matte black crust. If it struck something on the ground, part of the crust might have chipped off, revealing a lighter interior.

Anyone who thinks they have found such a piece may contact Wasson by e-mail:

wasson@igpp.ucla.edu

or regular mail at UCLA.

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

It Came Out of the Sky

The mysterious green flash that lit up skies in parts of the Southwest Oct. 3 was indeed a meteor, and scientists have been able to track its trajectory.

(1) The meteor apparently skipped off the upper atmosphere over New Mexico.

(2) It circled the Earth and was spotted over California 100 minutes later, at 8:44 PST.

(3) It crossed Santa Barbara, went north of Bakersfield and disappeared in the foothills around Kernville.

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