A space rock that exploded in the atmosphere near Iceland was only the fifth asteroid that has been observed before an impact with Earth
A small asteroid harmlessly collided with Earth on 11 March, creating an explosion in the atmosphere over the Arctic, just hours after astronomers spotted it for the first time.
The space rock, named 2022 EB5, was first detected at around 7.20pm GMT at Piszkéstető Station Observatory in Hungary by Krisztián Sárneczky, an astronomer at Konkoly Observatory in Budapest. Other astronomers were then able to track it before it plunged through the skies to the north-east of Iceland just after 9.20pm GMT. It is one of only five asteroids to have been found and observed before hitting Earth.
“The very rapid dissemination of information from the discoverers allowed other astronomers to make more observations from different vantage points with enough lead time to calculate a precise orbit and its intersection with Earth,” says Mark Boslough, an asteroid impact specialist at the University of New Mexico.
Thankfully, the asteroid was sufficiently small that it posed little danger – provisional estimates suggest it was around 1 to 2 metres across.
“Impacts of this size can be considered completely harmless. They typically create so-called ‘airbursts’ at altitudes of about 40 kilometres above ground,” says Richard Moissl at the European Space Agency’s Planetary Defence Office.
A signature of the disintegrating asteroid was picked up by infrasound monitoring stations that listen out for pressure waves from nuclear weapons tests. Peter Brown at Western University in Ontario, Canada, who is an expert at interpreting such data, tweeted that the energy released by the detonating space rock could have been equivalent to around 2 kilotons of TNT.
Moissl says events like these allow astronomers to make measurements that can shed light on characteristics such as an object’s density or composition. “With only optical observations of asteroids passing by Earth, we might never know more about their physical properties. But if a previously tracked object is also observed during its atmospheric entry and break-up, we can learn more about these quantities,” he says.
Impacts can also give modellers like Boslough a chance to test how well their simulations describe reality. “2022 EB5 was an experiment that nature provided for us,” says Boslough. “The more confidence we have in our models, the better we do our jobs at assessing impact risk for planetary defence.”
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Article amended on 15 March 2022
We clarified where the asteroid was first detected.
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