(image from vestic.ro)
It’s been exactly a month since all the Mayan Calendar ‘End of the World’ Hoo-Ha; and happily we are still here. Since the apocalyptic event of the decade turned out to be yet another ‘end of days’ damp squib that passed without the merest hint of a final trump, should we now relax and breathe easy, or does further trepidation threaten us in the near future?
Of all the disaster scenarios that were postulated for the end of the Mayan Calendar, one scenario is not only a real possibility, it is (pardon the pun) a dead cert. The only problem is, there is no definite date upon which to pin your worst fears and find a sturdy table to cower beneath. This particular event could happen at any time – tomorrow, next week, next month, next year or even next century. We are, of course, talking about a collision between the Earth and an asteroid or comet.
Earth has been hit on many occasions in the past. By studying the fossil record, palaeontologists have found that there have been regular mass extinctions of life on Earth occurring on average around every 100 Million years. These mass extinctions have been attributed to huge rocks or comets slamming into the Earth causing planet wide upheaval. The last such collision occurred around 65.5 million years ago, which wiped out 75% of life on Earth, both on land and in the sea. This event brought about the end of the dinosaurs, making way for the emergence of mammals such as horses, whales, bats and primates.
Extensive research and detective work revealed that the culprit for the last mass extinction was an asteroid measuring 10 Km (6 miles) in diameter that smashed into the Yucatan Peninsula leaving a 180 Km (110 Miles) diameter crater, which currently stands as the largest confirmed impact crater yet discovered on Earth. The explosion on impact released an estimated energy output equivalent of 100 Tetratons of TNT, which is almost two million times the destructive power of the biggest man made bomb (known as the’ Tsar bomb’) which has a yield of around 50 Megatons. That such a relatively small chunk of rock can release so much energy and cause the extinction of 75% of all life on the planet is a very sobering thought indeed.
All around the solar system, on planets and moons that do not have much in the way of active geological processes or erosion caused by having a substantial atmosphere, evidence of planetary bombardment is all around. From the craters on the Moon to those found on Mercury and Mars, all bear witness to huge collisions at some time in their existence. In short, the solar system is a hazardous place in which to live. Earth does not bear as many scars as the aforementioned worlds due to it being a living planet with active processes which have obscured most of the signs of past bombardment. However, if you look closely, the evidence is there. We have not been spared impacts in the past.
It is only in the last thirty or so years that our attention has been seriously drawn to this very real hazard from space, and to that end studies have been mounted to assess how just much of a threat we are under. Collectively these studies and projects are known as Spaceguard, a term coined by Arthur C Clarke in his 1973 novel ‘Rendezvous with Rama’.
Artists Impression of Comet Shoemakker-Levy 9 approaching Jupiter
(Image from: http://astronomy.wikia.com/wiki/Shoemaker-Levy_Project)
In 1994, Comet Shoemakker-Levy 9 broke up into a series of fragments which impacted on Jupiter over a period of seven days. To everyone’s surprise, a single fragment of the comet created a dark spot in the Jovian atmosphere over 12,000 Km across (7,456 Miles). The energy released by this collision alone was estimated to be 600 times the yield of the World’s entire nuclear arsenal. Shoemakker-Levy 9 was a wake up call for those who thought that asteroid/comet detection programmes were a waste of time and money.
It has been estimated that there are around 4,700 (plus or minus 1,500) potentially hazardous asteroids with a diameter greater than 100 metres which cross Earths orbit. Of these, only 20-30% have been discovered and tracked to date. Although a 100 metre object colliding with us is not classed as an Extinction Level Event, such an impact would cause much loss of life and worldwide upheaval should it ever strike a major population center.
Spaceguard projects have two important objectives: The first, as we have already discussed, is to track any potentially hazardous objects; and the second is to give us as much warning as possible in the event of discovering an object on a collision course with the Earth.
If we have enough notice, there are a number of strategies available to avoid a collision, ranging from crashing spacecraft onto the hazardous objects or using spacecraft to tow them out of harm’s way; to painting them white so that they absorb more sunlight and receive a bit of a solar push which hopefully will divert them off their course sufficiently to avoid collision. However, there is only one sure-fire way of guaranteeing the survival of our species from the threat of collision, and that is to colonise other places in the solar system and elsewhere. At the moment we have all our eggs in one fragile basket, and as previously stated, that basket is in a very precarious environment.
Using a Spaceship’s mass to tow an asteroid off a deadly collision course
(Image from impactlab.net)
The next object due to make a close pass of the Earth will be Asteroid 2012 DA14, a 40 metre (131 Ft) object which will be making a record breaking close pass to Earth on Feb 15th this year. The asteroid will miss us by a mere 27.000 Km (17,200 Miles). I know this doesn’t sound very close, but considering that this object will pass closer to us than the distance we have placed artificial satellites in geosynchronous orbit around the Earth (42,160 Km or 26,200 Miles), you begin to get an appreciation of how close this object will pass.
Don’t worry, this one is not going to hit us, and even if it did, this particular object is not a planet killer. So for those of you who decided not to buy Christmas presents with the excuse that there was a chance that the world would end last December, I recommend that you DO go out and buy Valentines cards and gifts as planned for our loved ones on the 14th, otherwise you may experience an ‘end of the world’ of a very personal nature.
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As the asteroid makes its closest pass, it should be visible using a good pair of binoculars (weather permitting) from Europe. For more details on how to observe this unique event, go here
*UPDATE*
Here’s a handy diagram from the lovely People at Jodrell Bank showing UK based Skywatchers where to look to get the best chance of seeing tonight’s (15/02/2013) record breaking flyby.
For more info go here
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