This post has been updated. See note below.
If a meteor was heading toward California, would residents have any warning?
It all depends on the size of the space rock and the time of day.
At night, astronomers can see an object hurtling toward Earth through a telescope. During the day, it’s nearly impossible.
A meteor lit up the sky in Russia Friday morning for 30 seconds before breaking apart about 15 miles above Earth. NASA estimates that it weighed around 10,000 tons and was 55 feet in diameter, making it the largest space rock to enter the planet’s atmosphere since the 1908 incident in Tunguska, Siberia.
The meteor released an estimated 500 kiltons of energy, creating a blast that broke windows and left hundreds of people with injuries. No one saw it coming.
“It’s hard to find small objects in the daylight until they get closer,” said Paul Chodas, a scientist at NASA’s Jet Propulsion Laboratory, during a teleconference on Friday. “An asteroid needs to be found against a dark sky.”
Caltech astronomer Mike Brown said a region might have one to two hours of warning if a meteor was detected at night.
But with astronomers already monitoring hundreds of other celestial objects, it might be a difficult task.
“You would have to look everywhere,” said Brown.
NASA did identify Asteroid 2012 DA14 — a rock roughly half the size of a football field — a year before it safely passed our planet late Friday morning.
Scientists have stressed that the asteroid was not related to the meteor in Russia. “It is an amazing coincidence,” said Chodas.
The fireball was so small that no searches being conducted at Caltech could have found it, said Brown.
Astronomers at Caltech and JPL routinely look for large objects that could impact Earth. For “big ones,” Brown said, the public would receive notice 10 or more years in advance.
Right now, Brown said, there is no object floating in the sky that is worth worrying about. The event in Russia was relatively mild, he added.
“As dramatic as the events in Russia were, it wasn’t that devastating,” he said. “It was traumatic and people were injured, but it’s like a mild train wreck. It’s not a huge Earth-changing event.”
[Editor's note: NASA originally estimated that the object that exploded over Russia weighed 7,000 tons and was 49 feet in diameter, based on initial reports. They updated that estimate on Friday night.]
-- Tiffany Kelly, Times Community NewsCopyright © 2015, CT Now