Large asteroid to pass Earth today
Later today, probably while I’m still sitting in an airport trying to find a way to get to #Goldschmidt2014 (so far United has delayed me by ~10 hours, follow here for conference tweets), a very large space rock is going to pass fairly close to Earth. There is no danger but it provides a number of good lessons.
This asteroid is a potentially hazardous asteroid named 2014 HQ124. In the name of an asteroid, the first number gives the year it was discovered; in this case, 2014. The first detail you should notice is that this potentially hazardous, near-earth asteroid was only discovered in April of this year.
In 2009, NASA launched the WISE spacecraft, a telescope that used infrared light to survey a large fraction of the sky. Objects like asteroids radiate light at these wavelengths, so the WISE telescope discovered a lot of them, both in the asteroid belt and closer to Earth. After its main mission ended, the mission was renamed NEOWISE and focused on discovering asteroids close to Earth that could be impact hazards.
Unfortunately, the telescope was put into hibernation in 2011, but following the explosion of an asteroid above Chelyabinsk Russia last year, $5 million a year was redirected to turn the telescope back on and resume the search for potentially hazardous asteroids. 2014 HQ124 was identified in April by this telescope, and subsequent observations characterized its size and orbit.
The asteroid was estimated to be ~325 meters in diameter (over 1000 feet) and later today will pass about 1.25 million kilometers from Earth. That’s about 3x the distance between the Earth and the Moon.
For scale, this asteroid is probably about 10x the size of the rock that created Arizona’s meteor crater. If it hit Earth, it would cause an explosion equivalent to the detonation of about 2000 megatons of TNT (20 times larger than the biggest nuclear detonation ever). On average, a rock this size hits Earth about once every 100,000 years.
To stress what I said several times, this asteroid will miss Earth by a lot today. It will be 3x as far from us as the Moon is. But there are lessons to take here.
First, this asteroid is a Near Earth Asteroid (NEA) capable of producing enormous damage and it was just discovered this year. It is regularly stated that >90% of the asteroids larger than 1 kilometer capable of hitting Earth have been discovered, but rocks of this size are capable of doing significant damage to Earth and this one wasn’t discovered until very recently.
Rocks this size pass within this range of Earth once every few years. A 600 meter rock will pass about 3 Lunar Distances from Earth next January. But, these passes should still serve as a reminder that we sit, to some extent, in a shooting gallery.
It takes resources like WISE, money, and potentially other facilities in the future to find and track these objects. Until the Chelyabinsk explosion, the resources put into this problem were limited. They’re non-zero now, but finding these dangerous rocks is still an effort that will take years to decades at current rates. Furthermore, there’s no guarantee that, as memory of the Chelyabinsk explosion fades, the political will and funding to find these objects won’t fade with it.
There will also be opportunities for science in this pass. Most of the time, these asteroids appear as points of light in the distance to telescopes, but the closer they get to Earth the more we can see. Facilities like the giant Arecibo observatory in Puerto Rico will observe this asteroid as it passes and in the case of Arecibo, it will use radar to determine the shape and other properties of the object. The more we observe objects like these when they do pass, the better we will be at understanding what they’re made of, how they behave in their orbits, and potentially in the future what we could do to deflect them. There will be several webcasts of the pass of this object from these observatories; details can be found at Slooh.
For whatever reason, this object seems to have been nicknamed “the Beast” in popular media. The Beast isn’t going to hit Earth today, but it is both an opportunity to do interesting science and a reminder of what else is out there.
Image credit: P. Carrill, ESA.
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