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The meteor that exploded in a brilliant burst of flame above the Bay Area on Wednesday was a lonely remnant from the birth of the solar system, and may have left its rocky debris in a band stretching east of San Rafael toward Napa and Sonoma, the astronomer who calculated its path reported Friday.

Peter Jenniskens, an internationally known meteor scientist at the SETI Institute in Mountain View, told The Chronicle that two separate video images of the explosion showed that the meteor’s rocks could not have fallen over Martinez as early reports said.

Jenniskens plans to be on the ground this weekend, looking for black rocks in the area he has defined.

“But it’s going to be difficult because they could be scattered really widely, where the wind may have carried them while they were falling,” he said. “It was a slow-moving fireball, which greatly increases the chances that somewhat larger pieces survived.”

Images of the exploding object as it fell from 53 miles high to 24 miles were caught by two cameras – one manned by volunteers at the College of San Mateo and the other, in Sunnyvale, belonging to the NASA project called Cameras for Allsky Meteor Surveillance, which Jenniskens directs.

The cameras’ images gave him and his computer two tracks to determine the fall’s direction and to show where the shattered rocks and fragments may have hit the ground, he said.

The meteor was actually a fallen asteroid, Jenniskens said – one of more than 100,000 that now circle the Sun in the Asteroid Belt between the orbits of Mars and Jupiter.

Asteroids in the belt range in size from the dwarf planet Ceres, 590 miles across, to tiny pebbles and even dust particles. They are extremely old, left over from the huge cloud of dust and rocks that surrounded the sun and all its planets when the solar system was forming some 4.7 billion years ago, astronomers say.

Wednesday’s meteor explosion could not have come from a comet, Jenniskens also explained, because comets are extremely fragile and their remnants consist only of extremely small fragments, smaller, even, than small rocks.