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Our Terrifyingly Crowded Solar System: New Video Reveals Just How Many Asteroids Are Out There
 Daily Mail UK
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August 28, 2010
It's not just our country that's a little over-crowded - our whole solar system is too.
A fascinating colour-coded video illustrates how we have become increasingly aware of the number of asteroids flying close to Earth as telescopes improve.
The footage shows the discovery of every new asteroid over the past three decades and charts it on an increasingly congested map of the solar system.
Created by British astronomer Scott Manley, the three-minute clip - which is the equivalent of two months per second - starts with a sprinkling of white 'dust' around the edge of the planets.
Over the years, and as more telescopes are added to the experiment and detection methods improve, this becomes a dense green 'ring' as the number of 'minor planets' found in the asteroid belt increases.
Worryingly, the red dots are those which fly around the inside the Earth's orbit - with the footage showing that some appear dangerously close.
The final colour of an asteroid on the video indicates how closely it comes to the inner solar system - with yellow indicating Earth-approachers.
Mr Manley created 'maps' every day from 1980 to 2010 to pinpoint the location of asteroids discovered by telescopes.
Thirty years ago, we knew of just 8,954 within our solar system. Today, we have discovered 530,091 - forming a green 'eye' of minor planets.
Mr Manley, a former research student at Armagh Observatory in Northern Ireland, said: 'The images are created by using the known orbits of the asteroids to figure out where they've been on a day-to-day basis.
'Just like we can figure out where the Earth, Mars and Venus have been, we can do the same with anything orbiting the sun.
'I created maps for every day over the last 30 years - that's about 11,000 images - then I combined them to make a video.'
Asteroids are small solar system bodies that orbit the sun. They are smaller than planets, and are sometimes referred to as minor planets.
Their size ranges from 950km for the largest known asteroid, Ceres, to just tens of metres across.
Small asteroids - five to 10 metres in diameter - enter the Earth's atmosphere about once a year, but normally explode before impact. Larger minor planets - of about 1km in size - strike every 500,000 years.
But although some of the asteroids on Mr Manley's map look as though they are terrifyingly close to the Earth, he has some words of reassurance.
'The positions are all to scale, but the sizes of objects are expanded to make them visible,' he said.
'One pixel on the screen is one million kilometres - so even if an asteroid appears right on top of Earth in the video it could be up to a million kilometres away. That's more than twice the distance to the Moon.'
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