More reports of Sunday evening’s fireball have been posted on this blog and the American Meteor Society Fireball page. Thanks to everyone who has been posting! If you would like to make an official report please visit the American Meteor Society’s Fireball Report page. The form is very simple and you don’t need to know any astronomy to make a valuable contribution.
The fireball occurred on Sunday evening, January 18, at ~5:30 pm (give or take 20 minutes). Amazingly this was only ~15 minutes after sunset for people on the coast so the sky was still very bright. The fireball must have been quite a spectacle to be seen against such a bright sky.
Based on the reports submitted so far, it was seen from 4 states (California, Nevada, Utah and Arizona). Here’s a map of the sightings reported so far.
Most people said it was a white/blue though a few observers noted it changed into many colors. This is consistent with a meteor. The fireball ended its passage through the atmosphere with a bang, something astronomers call a “terminal burst”. This marks the final break-up, or explosion, of the small asteroid that created the fireball. Many reports also mentioned that a smoky trail was visible for several minutes after.
So what was it? Most likely it was a small asteroid or “space rock”. Probably no bigger than a basketball, it burnt up in the Earth’s atmosphere as it traveled at a speed of a few tens of miles per second. Though it may have looked like it was only a few hundred feet above the ground, it was in fact 40-60 miles up. It is definitely possible that some small pieces survived to hit the ground.
Turns out a second very bright fireball was seen over northern California later the same night. At least 3-4 people reported a fireball in the San Francisco area at 11:26 pm. The two fireballs are probably unrelated.
So far no videos of the twilight fireball have surfaced. Because the sky was so bright, most of the all-sky meteor cameras were still off. The second fireball was captured by an all-sky meteor camera in Yuba City operated by Richard Spalding. His video can be seen here.