The night sky in the northern Australian state of Queensland lit up on May 20 as a meteorite flew through the atmosphere and hit the ground with a huge sonic boom.
Meteorite streaks across Queensland sky. Video : Guardian
Smartphone, car camera and security camera footage from businesses and homes from Cairns on the east coast to Normanton on the Gulf of Carpentaria showed a fireball rapidly growing in size as it descended closer to the ground, followed by a green-blue flash.
Cairns Airport shared colour footage showing the sky flashing green, then yellow as the meteor flew by at 9:22am local time on May 20. Residents in the small town of Croydon, about 500km west of Cairns, said they also felt the explosion and heard a huge boom.
Dr Brad Tucker, an astrophysicist at the Australian National University, said the rock was likely between 0.5 and 1 meter in size, smaller than an average-sized meteorite, and was travelling at 150,000 km/h. Most meteorites are made of chondrite, but in this case the green colour before the explosion was likely due to iron and nickel fragments being overheated as the rock broke apart before it hit the ground.
According to Tucker, the meteorite will not create a crater because it will break into many pieces before hitting the ground. Although it burns up due to friction as it falls through the atmosphere, most of the rock will still be frozen by the time it hits the ground. "The friction builds up, creating a halo and reaching a breaking point, emitting a flash of light and a sonic boom. That's what we're most concerned about with most meteorites. It's a mid-air explosion, but if it happens over a residential area, it could cause damage. This one is pretty small, but we're pretty worried about 10-20 meter meteorites," Tucker said.
In 2013, a 20-meter meteor exploded over the Russian city of Chelyabinsk. Scientists discovered that the rock exploded with the energy equivalent of 500 kilotons of TNT. The explosion knocked people off their feet, shattered the windows of 3,600 buildings, and collapsed a factory. At its peak, the Chelyabinsk meteor was 30 times brighter than the sun, causing burns to the skin and retinas of people nearly 30 kilometers away.
An Khang (According to Guardian )
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