An asteroid with the fetching name of 2009 DD45 made a surprise visit to Earth on March 2, 2009. As Fox News reported on the day of the fly-by, “The rock, estimated to be no more than [60 metres] wide, zoomed past our planet at an altitude of [around 63,000 kilometres] at 1:44 p.m. universal time.”
That may sound like a safe distance, but in astronomical terms it’s like two cars missing each other on the highway by the width of a coat of paint. Astronomers call these things close-approach objects. But, when they talk about “close” they do so in galactic dimensions: they’re thinking in terms of objects being as near as one Astronomical Unit, or 150 million kilometres.
Australian Comet Hunter
DD45 was only spotted three days before its close encounter by Rob McNaught at the Siding Spring Mountain Observatory in New South Wales, Australia. According to the Australian news website Crikey.com the asteroid “is similar in size to the dead comet shard that exploded with the force of a large hydrogen bomb over a then largely uninhabited region of central Siberia on June 30, 1908.” This “Tunguska asteroid,” as it’s known, was so small that it didn’t even reach the ground intact yet its blast wave toppled 60 million trees.
But, there are plenty of other rocks out there to worry about.
Near-Earth Objects
Most chunks of space rock spend their time buzzing about the Asteroid Belt between the planets Mars and Jupiter. Every so often one of them escapes its orbit and flies off into space.
The National Aeronautics and Space Administration (NASA) has so far counted 4,780 asteroids, comets, and meteorites that are on the loose and could swing by our neighbourhood. There are thought to be many more that haven’t yet been spotted; 2009 DD45 being an example.
The Asteroid 99942 Apophis
One that NASA’s been keeping a wary eye on is called 99942 Apophis. This is an asteroid with a diameter of about 300 metres, big enough to make a nasty mess of anything it bumps into.
Asteroid 99942 Apophis caused a bit of a flap in 2004. It seemed its travels were going to bring it a bit too close to Earth for comfort. In fact, it looked as though there was a 2.7% chance it was going to hit us in 2029. More observations have been made and the panic level has gone down. Now, NASA's Near Earth Object Program says there’s a very, very slight chance of a collision in 2036, and an even more remote one for the following year.
Avoiding an Asteroid Collision
A massive asteroid collision, about 65 million years ago, bumped off the dinosaurs.
Humans have no intention of falling victim to the same catastrophe. NASA has plans to send a probe up to meet Apophis in 2014. This will help scientists learn more about the asteroid’s path and, if necessary, nudge it onto a voyage that misses Earth.
There’s no way to avoid the destruction of earthquakes, storms, and other natural disasters that occur on the planet. But, there may be tactics for avoiding some of the dangers of the Universe. As the people at the Near Earth Object Program point out, “…asteroid impacts are the only major natural hazard that we can effectively protect ourselves against.”
Rupert Taylor - Rupert Taylor is the editor of a magazine that provides background to current events.
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