With the pending approach of a large asteroid the day after Valentine's Day, one which will come between us and the moon, it is reasonable to ask if we are prepared. The asteroid in question is called 2012 DA14, and is about 150 feet across in size and traveling at a speed of 17,450 miles per hour.
NASA scientists have told us that there is nothing to be worried about (I remember a similar statement in the movie
Melancholia, though that did not work out too well). Even in the worst case scenario we are not looking at a 6-mile wide asteroid like the one that hit 66 million years ago (the effect of which is being
questioned), but this is quite an event. The closest the asteroid should get will be about 17,200 miles above the Earth's surface, or about one-tenth the distance between Earth and moon. To date, the only Earth objects threatened by this large rock would be some of the weather and communications satellites circling the Earth. The International Space Station orbits well below the expected path of 2012 DA14 at an altitude of 240 miles. You can see some of the risk calculations in the box below from
NASA (good luck).
NASA noted that this asteroid was only discovered recently:
2012 DA14 has not been in our catalogs for very long -- it was discovered in February 2012 by astronomers
at the La Sagra Sky Survey program in southern Spain and reported to the Minor Planet
Center. The asteroid had just made a fairly distant passage by the Earth, about 7 times farther
than the distance to the Moon when it was first detected by the Spanish group.
Since 2012 DA14's orbital period around the Sun has been about 368 days,
which is very similar to the Earth's, the asteroid made a series of annual
close approaches, this year's being the closest. But this encounter will
shorten 2012 DA14's orbital period to about 317 days, changing its orbital
class from Apollo to Aten, and its future close approaches will follow a
different pattern.
The close approach this year is the closest the asteroid will come
for at least 3 decades.
This passage of 2012 DA14 by the Earth is a record close approach for a known object of this size.
A few other known asteroids have flown by the Earth even closer, but those asteroids were smaller.
On average, we expect an object of this size to get this close to the Earth about once every 40 years.
An actual Earth collision by an object of this size would be expected much
less frequently, about once every 1200 years on average.
This all sounds very reassuring, until you
also read:
Scientists believe there are approximately 500,000 near-Earth
asteroids the size of 2012 DA14. Of those, less than one percent have
been discovered...
Asteroid 2012 DA14 will not impact Earth, but if another asteroid of a
size similar to that of 2012 DA14 (about 150 feet across) were to impact
Earth, it would release approximately 2.5 megatons of energy in the
atmosphere and would be expected to cause regional devastation.
A comparison to the impact potential of an asteroid the size of 2012
DA14 could be made to the impact of a near-Earth object that occurred in
1908 in Tuguska, Siberia. Known in the asteroid community as the
"Tunguska Event," this impact of an asteroid just slightly smaller than
2012 DA14 (approximately 100 – 130 feet/30-40 meters across) is believed
to have flattened about 750 square miles (1,200 square kilometers) of
forest in and around the Podkamennaya Tunguska River in what is now
Krasnoyarsk Krai, Russia.
Good grief!
Do you feel better now?
Update: All is well. 2012 DA14 safely passed by Earth with no damage to those below. NASA provided the image below from the telescope known as the
iTelescope.net Siding Spring Observatory in Australia.
