On February 15th a ball of rock and iron blasted through the Earth’s atmosphere at 40,000 mph and after a 32.5 second light show impacted Chelyabinsk, Russia at 3:20 UTC. NASA estimate the meteor was 17 metres and had a mass equivalent to 1,300 African elephants. On explosion it released energy equal to around 30 Hiroshima-type atomic bombs.
Gases inside the meteor heated on entering the earth’s atmosphere causing an explosion and the meteor to disintegrate and land at 3 separate sites; lake Chebarkul, a nearby zinc factory and the Ural mountain region. Shockwaves, created from the sonic boom as the meteor burst into fragments, caused more harm than the impact. Buildings were damaged and windows shattered, leaving people covered in glass. It has been estimated that more than 1000 people were injured, two seriously, but there were no fatalities.
The meteor is the largest reported since 1908, when one hit Siberia. NASA states that they expect this sort of event to occur “every 100 years on average”. Luckily, no one has ever reportedly been killed by a meteor falling from the sky, as most of the earth is uninhabited by humans.
It has been confirmed by NASA and the European space agency that this event is unrelated to the DA14 asteroid flyby, which came from a different direction and made a safe pass by Earth just hours after the meteor strike.
Magnitude of meteor impact competes with nuclear explosions, but space rock is still far too small for our technology to spot. Since current telescopes can only detect near-Earth objects more than 100 m in size, the fiery Russian meteor was completely undetected until visible in the sky. Over the past 15 years, NASA has discovered over 95% of the largest asteroids that would have devastating consequences if they were to impact earth. However less than 1% of smaller DA14-like objects, having the capability of wiping out an area the size of London, have been discovered. Monitoring these objects is important because deflection is possible but only with decades of warning.
But there is light at the end of the telescope, there are many organisations that are currently working on new telescopes to detect these smaller objects, these include the European Space Agency’s Gaia mission and B612 Sentinel mission. Sentinel is currently under construction and will hopefully be fired off to space in a Venus-like orbit around the sun, looking outwards to map asteroids in the inner solar system. Over its 230 day orbit and 6.5 years of operation, Sentinel is hoped to detect the other 99% of smaller asteroids that are likely to impact the Earth.
A few definitions…asteroid, meteoroid, meteorite, meteor?
A meteoroid is a small particle from a comet or asteroid orbiting the sun and on entering the Earth’s atmosphere it can vaporise, becoming a meteor (otherwise known as a shooting star) or if the object survives its passage through the earth’s atmosphere and impacts on the Earth it is then a meteorite.
An Asteroid is a rocky object orbiting the sun in the inner solar system and a comet is an object composed of ice, dirt and grit in the outer solar system. Asteroids and comets are the leftover debris from the creation of the planets in our solar system, including the Earth. So studying the meteorites that impact our planet can tell us important information about how the Earth formed 4.6 billion years ago.
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Philippa Hardy