Expert explains what Summit County residents saw light up the night sky over the weekend |

Expert explains what Summit County residents saw light up the night sky over the weekend

A meteor is seen from Silverthorne on Sunday, Oct. 3.
Loren Vawser/Courtesy photo

The fireball Summit County residents saw shoot across the sky over the weekend was part of the South Taurid meteor shower and traveled toward Earth’s atmosphere at about 55,000 mph, according to Bill Cooke, lead for NASA’s Meteoroid Environment Office.

On Sunday, Oct. 3, Summit County residents — and their cameras — witnessed a moment of bright sky at around 4:30 a.m. followed by a fireball streaking across the sky and dipping down below the horizon. Then, over three minutes later, a loud boom was heard.

The American Meteor Society tweeted that a bright fireball had been spotted west of Denver on Sunday and that the fireball was also seen from New Mexico and Wyoming. The society’s post about the event noted that it had received more than 40 reports about the fireball.

“The meteor started out in the mountains just east of Vail and moved slightly northeast, and the speed was approximately … 55,000 mph. It lasted a couple seconds, and during that time, it covered a little over 30 miles through the atmosphere,“ Cooke said. ”It broke apart 35 miles up above Vasquez Peak.”

Cooke said the meteor looks to be a member of the South Taurid meteor shower that’s currently going on. This means the fireball people saw was a piece of Comet Encke burning up in the atmosphere.

The piece was observed from space by the geostationary lightning mappers on the GOES-16 and GOES-17 satellites. Cooke said these instruments are designed to detect lightning but will also occasionally detect brighter fireballs and can be used to calculate the energy of the fireball.

Black arrows represent eye-witness reports of the fireball seen Sunday, Oct. 3. The green arrow shows where the fireball was observed with a special meteor camera. The blue arrow shows the meteor’s trajectory.
Bill Cooke/NASA Meteoroid Environment Office

The fireball was about 10 inches in diameter and weighed about 40 pounds, Cooke explained. He said what people saw was the meteor burning up in the sky as it hit the atmosphere.

Cooke explained that when a meteor hits the atmosphere, pressure forms in front of the meteor due to its speed, and a partial vacuum forms in the rear.

“When that difference in pressure between front and back is greater than the rock’s structural strength to hold it together, it breaks apart violently in a brilliant flash of light,” Cooke said, explaining the flash that people saw. “Now as it burns up, it leaves a continuous streak of light, but those flares, those sudden increases in brightness, are caused by bits of the meteor breaking up. And at the very end, it just completely broke apart.”

The two dots in the center of the map are the fireball Summit County residents saw Sunday, Oct. 3, as seen from space. Satellite instruments picked up the two brightest flares of the fireball. The eastern flare is the endpoint of the fireball.
Bill Cooke/NASA Meteoroid Environment Office

Despite the uniqueness of the fireball for some Summit County residents, Cooke said the event is very common.

“You see fireballs all over the world,“ Cooke said. ”They occur every night all over the world. This one was a little bit brighter than the full moon, about 2 1/2 (to) three times brighter than the full moon, so it was a fairly bright fireball.”

The South Taurid meteor shower that the meteor was part of is an interesting shower, Cooke said, because you wouldn’t know the shower was occurring except for the occasional fireball. The Taurid shower’s rate amounts to two or three meteors per hour, while the Perseids meteor shower rate is 100 meteors per hour. Cooke added that the Taurid shower occurs at this time every year, and while sometimes the shower is more intense than other years, nothing unusual is expected this year.

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