Right now, there are about 15,000 chunks of rock orbiting worryingly close to Earth. These appropriately named Near-Earth Asteroids (NEAs), all within about 0.2 billion kilometers (0.12 billion miles) from the Sun, whizz by our world at irregular intervals, but this month it appears that at least three, possibly four, will all zip by the blue marble on Wednesday, December 21.
As reported by NEOShield, an international consortium to address impact threats to Earth, asteroids 2006LH, 2010XN, and 2006XD2 are all going to pass by Earth.
The first is the smallest being just 45 meters (148 feet) in diameter and moving at a speed of 9.4 kilometers (5.8 miles) per second. The third, at 260 meters (853 feet) in length, is by far the most massive. Moving at 13.6 kilometers (8.5 miles) per second, it’s also the fastest.
Let’s just assume that 2006XD2 is a stony asteroid, with a mineral composition roughly that of basalt. Let’s also assume it’s spherical. Both of these are massive simplifications, but it means that we can estimate how much kinetic energy 2006XD2 will be released if it hit a continent on Earth at a 90° angle.
This means that 2006XD2 has a mass of around 30 billion kilograms (33 million tons), and would impact the planet with 2.8 quintillion joules of energy. Yes, that’s a lot. It’s still over 100,000 times less energetic than the dinosaur-killing asteroid impact 66 million years ago, so no biggie really.
Don’t worry though! Although many media outlets would claim that they are going to be “near-misses” – and they would be right in terms of astronomical distance – the distances they are going to be at their closest approach aren’t worth getting anxious over.
The small 2006LH will be the closest at 14.5 times the Earth-Moon distance, and the big baddie 2006XD2 will be passing by at 18.9 times the Earth-Moon distance.
Others are reporting that a fourth NEA, 2015YQ1, will also pass by Earth on the December 21, but we cannot verify this at present, and NEOShield make no mention of it.
Still, it’s not a stranger to close encounters with the third rock from the Sun. This time last year, the 7-meter-long (23 feet) 2015YQ1 made it within roughly 1.4 times the Earth-Moon distance.
If you’ve got a powerful enough telescope, you might be able to see some of these NEAs depending on their angle of approach relative to the Sun. Regardless, it’s comforting to be reminded that programs out there exist that keep an eye on all these rocky torpedoes, one of which could one day threaten all life on Earth.