Arizona meteor totally unrelated to tonight's eye-popping Geminids
The Arizona fireball meteor rattled windows and lit up social media Tuesday night. In unrelated news, the 'best show of the year,' the Geminid meteor shower, has started and will peak Friday night.
Two things are true: (1) A "fireball" meteor lit up Arizona skies Tuesday night. (2) The most dramatic meteor shower of the year is expected to peak tomorrow night. But despite their coincidental timing, they have nothing to do with each other.Skip to next paragraph
In Pictures Meteors
Subscribe Today to the Monitor
By all accounts, the Arizona fireball meteor was impressive, flaming orange-red and delivering a sonic boom or two that rattled windows and prompted more than one "What was that?!"
The fireball was unrelated to the Geminid meteor shower, a large and impressive meteor shower that has been known to include fireballs and other dazzling light displays. Think of it like this: Not all the drivers on the road at 6 p.m. are commuters. Some are long-haul truckers, some are unemployed people running errands, and some are lost tourists.
How can scientists be so sure that the fireball isn't related? "It's pretty easy," says Bill Cooke, a meteor scientist with NASA. "We rule it out on speed and direction."
RECOMMENDED: Are you a space whiz? Take our quiz!
Tuesday night's fireball passed by two meteor cameras, says Dr. Cooke, enabling scientists to measure the speed and the direction of its motion. "A Geminid would appear to be coming from the constellation of Gemini – hence the name, Geminid – and it would also be moving 35 kilometers per second (78,000 miles per hour). The Arizona fireball, when it hit the top of the atmosphere, was not coming from the constellation of Gemini. It was coming from a radiant north of that constellation, and it was moving only 20 kilometers per second (45,000 m.p.h.), so that automatically meant it was not a Geminid."
On any given night, you can expect to see five to eight meteors per hour, says Cooke, who leads NASA's Meteoroid Environment Office. Those make up the "sporadic background," unrelated to any meteor shower. Arizona's fireball was one of those, he says.
Meteor showers deliver a much busier sky. At its peak Friday night and Saturday morning, the Geminids will average 100 to 120 meteors per hour, though the nearly-full moon will hide the fainter ones this year.
"It'll still be a very good show," says Cooke. "Our meteor cameras depicted at least 15 bright meteors – almost fireballs – last night, and we're still a night away from the peak." He recommends heading out after 4 a.m., when the moon sets, for the best observing.