Twin Cities Times
Wed, 31 Oct 2012 06:52 UTC
Twin Cities Times
Wed, 31 Oct 2012 06:52 UTC
Webber gave the meteorite to her neighbor Glenn Rivera as a birthday gift. He helped her analyze the chunk before calling scientists. The meteorite broke off from the meteor shower that blazed over the night sky at approximately 7:44 p.m. on Oct. 17. It also happened to be Rivera's birthday.
"As a result, Glenn was asked by the scientific team to ride in the airship Eureka from Moffett Field on Friday," said Leigh Blair, Rivera's mother. "They flew over Novato and all the way up to Lake Berryessa, following the calculated trajectory of the meteor, looking for signs of larger meteorites on the ground."
Peter Jenniskens, the meteor scientist at the Seti Institute, a nonprofit scientific and education organization that has projects sponsored by NASA and other foundations and research groups, at first dismissed the first rock because the surface appeared strange and weathered, unlike most meteorites. But everything changed when a second rock showed small specks of what seemed to be metal, when observed under a microscope.
Brien Cook, a meteorite hunter and Sacramento resident, found the second rock in the Novato area, but too dismissed it as a meteorite until the two chunks were compared. After cutting it open and looking inside, he knew he had found an extraterrestrial treasure.
Cook is offering one chip of his meteorite on eBay. It weighs 6.6 grams, and objects like it regularly sell for approximately $100 a gram, he said.
Lisa Webber, a University of California San Francisco nurse, found the meteorite in her backyard on Oct. 20. She returned the piece to Jenniskens, and he will send samples of both rocks to a noted meteorite expert Professor Alan E. Rubin of the Institute of Geophysics and Planetary Physics at UCLA.
Rubin believes that each rock is a stony meteorite called a chondrite.
The meteorite story got interesting when Jenniskens said on his NASA Ames Research Center webpage that Webber's house was hit by something during the fireball's descent on Oct. 17. After an examination using a petrographic microscope, Jenniskens thought he had made a false confirmation and said: "I sincerely thought it was, based on what appeared to me was remnant fusion crust. On closer inspection, that crust was a product of weathering of a natural rock, not from the heat of entry."
The meteorite made news after Webber heard a boom and its rattling aftermath near her garage. Three days later she decided to inspect her roof and yard, only to discover a golf ball-sized fragment weighing 63 grams on Oct. 20.
On the NASA Cameras for Allsky Meteor Surveillance project, cameras in Sunnyvale and at San Mateo College captured two views of the fireball. Scientists were able to calculate a trajectory and project a fall area in the North Bay, from east of San Rafael over to Novato and beyond toward Sonoma and Napa counties.
Meteors are hunks of rock and metal that have broken off from asteroids and fallen from space, breaking up as they enter Earth's atmosphere.
Jonathan Braidman, astronomy instructor at Oakland's Chabot Space and Science Center, said that the meteors hit the upper layer of Earth's atmosphere traveling 25,000 mph or more, but the atmosphere slows them down and breaks them up so that when they hit the ground they are only traveling between 200 and 400 mph. The boom that residents heard on Oct. 17 was a sonic boom, caused by the falling object traveling faster than the speed of sound, and was probably moving at more than 1,000 mph, Braidman said.
Braidman said the meteor heard Oct. 17 is not at all related to the Orionid meteor shower that peaked a few days later. The fireball found at the Webber home blew in from a different direction, opposite Orion.
Shortly after her discovery at 12:30 p.m. on Oct. 20, she asked Rivera to examine the chunk.
"I found a magnet and it stuck right to it," Webber said. "Glenn and I looked at it and were in awe."
Webber quickly emailed Jenniskens. Jenniskens and Webber's neighbor Luis Rivera inspected the roof and discovered a divot in a shingle that matched the size and angle of the chunk. The dent was located just above Kent Webber's study. Kent, Webber's husband, is the pastor at the Presbyterian Church of Novato.
Commonly small meteorites drop before larger ones. Because the fireball traveled from southwest to northeast, Jenniskens believes that larger fragments may have dropped near Novato and Sonoma.
Retired aerospace engineer Bob Verish has been in the Novato area since the Oct. 17 meteor sighting, when he heard about it during a different meteorite search in northern Nevada.
Verish has been doing meteorite searches for the past 12 years, and has worked with Jenniskens at other meteorite landings.
As part of Verish's hobby he created the Meteorite Recovery Lab based in Southern California. He has several hundred meteorites that he said he "self-collected" in California, Arizona and Nevada.
The search in the North Bay is in a fairly populated area, prompting Verish "to solicit the residents of Novato and Sonoma County to look to see if anything like a black rock might have landed in their yard" or even in their swimming pools.
He said the search through the area had led him to many vineyards, so he is asking workers to keep an eye out when in the fields.
Residents are also urged to look before massive amounts of rain, which makes for rust and a meteorite's breakdown by erosion.
"Jenniskens is certain there are more pieces out there to be found," Blair said. "Anyone who saw the zeppelin nearby in Marin and Sonoma is in the path where meteorites may have fallen. The hunt continues."
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