Fireball Explosion Over California-Nevada

Astronomers say a loud explosion heard across a large swath of Nevada and California on Sunday morning was likely caused by a meteor, just after the peak of an annual meteor shower.

The sound of the explosion around 8am prompted a flood of calls to law enforcement agencies on both sides of the Sierra Nevada in the two states.

Observers in the Reno-Sparks area of Nevada reported seeing a fireball at about 8 a.m. local time, accompanied or followed by a thunderous clap that experts said could have been a sonic boom from the meteor or the sound of it breaking up high over the Earth.

"It made the shades in my room shake hard enough to slam into the window a couple times," said Nicole Carlsen of the Reno area. "I kept looking for earthquake information, but (there was) nothing. I even checked the front of my house to make sure no one ran into the garage. I wish I had seen the meteor."

Some people in the two states reported seeing a fireball streak across the sky at the same time.

 Being daylight, most of the reports are of a white object with blue and green being most mentioned secondary colors.  The average brightness reported by witnesses was between that of the sun and the light produced by a full moon. While this is most likely a random event, there is a possibility this fireball was a member of the Lyrid meteor shower. 

"From the reports, I have no doubt it was a fireball," said Robert Lunsford of the Geneseo, N.Y.-based American Meteor Society. "It happens all the time, but most are in daytime and are missed. This one was extraordinarily bright in the daylight."

Marcia Standifer of Spring Creek, near Elko, and her husband were out drinking coffee when they saw the fireball at the same time. "It was a very bright ball of white light, then dimmer to the horizon," she said. "We thought this was very unusual due to the bright daylight and how vivid the object was."
Tracey Cordaro of North Las Vegas said the sighting "took my breath away." "It was amazing," she said. "It looked as if it was disintegrating rapidly, but was still quite large when it disappeared from my view ... (It was) bright green, visible in the bright sunlight."

A fireball is a meteor that is larger than normal. Most meteors are only the size of tiny pebbles. A meteor the size of a softball can produce light equivalent to the full moon for a short instant. The reason for this is the extreme velocity at which these objects strike the atmosphere. Even the slowest meteors are still traveling at 10 miles per SECOND, which is much faster than a speeding bullet. Fireballs occur every day over all parts of the Earth. It is rare though for an individual to see more than one or two per lifetime as they can also occur during the day (when the blinding sun can obscure them), or on a cloudy night, or over the ocean where there is no one to witness them. Observing during one of the major annual meteor showers can increase your chance of seeing another bright meteor.
Very few meteors actually reach the ground as 99.99% completely disintegrate while still 10-20 miles up in the atmosphere.

Dan Ruby of the Fleischmann Planetarium at the University of Nevada, Reno, says the reports indicate the meteor broke up above Earth somewhere over the Sierra southwest of Reno. When debris enters the atmosphere it creates explosions similar to the sonic boom of a fast-moving aeroplane, according to meteorologists.

There were no reports of earthquakes at the time.