One of the things that scientists are certain about concerning the near-Earth object asteroid 2012 DA14 barreling its way through the solar system on a near-collision course with our fair planet is that that is all that it will be -- a near collision. In fact, they've pretty much narrowed down the half-a-football-field sized space rock's closest position to Earth -- about 17,100 miles above the planet, cutting between low-flying satellites and the geosynchronous layer of communications satellites at about 22,000 miles. But what if scientists calculated wrong? What would happen if such a massive rock/meteoroid actually impacted the Earth?
Time magazine's Jeffrey Kluger took a fairly extensive look at such a scenario a day before the asteroid's flyby (Feb. 15) and the effects of such a cataclysmic meeting of an object the size of 2012 DA14 and the Earth would not be without great moment, especially if it crashed into or near a highly populated area or just off-shore from one.
An asteroid the size of a large yacht would, if it impacted on land and depending upon its speed, hit with the force of about a 3 megaton blast. What such an impact would do would create a blast radius of at least 20 miles, where even that distance would not stop tall building from having their windows blown out (although the buildings would be left standing). Half that distance from ground zero would see the skeletal structures of large buildings survive, but not regular domestic-type houses. Of course, just about anything within five miles of the blast would be leveled.
For comparison, the now famous Tunguska Incident of 1908 was caused by, NASA scientists believe, a meteor or comet that was 120 feet across. It's blast was estimated in the 3-20 megaton range. The damage was estimated at what would have been caused by 185 Hiroshima-sized bombs. It disintegrated in the Russian sky and leveled trees for 800 square miles.
Kluger's scenario in the Time piece has the space rock, which is traveling at nearly 17,500 miles per hour, impacting New York City. The cities extensive five boroughs encompass 469 square miles. The city is home to nearly 8.3 million people.
2012 DA14 is estimated to be able to trigger a blast at 180 Hiroshima-sized bombs, nearly the same as that of the Tunguska airburst.
And all the asteroid would have needed to hit the planet would be a slight nudge somewhere along its way, something that would have slightly altered its course a degrees. That could have been done by colliding with space rocks, gravitational pull from planets and other near-Earth objects, or even from the light of the sun (known as the Yarkovsky Effect).
But that's not going to happen, according to NASA and several other astronomical agencies.
This time.
The asteroid will, however, set a record for its proximity to the Earth for a space rock of its size since NASA has been keeping monitoring the skies.
NASA's Near-Earth Object (NEO) Project, which tracks rocks and meteoroids and small planetoids in the relative neighborhood, place at least 2,400 space rocks at least half a kilometer (.3 miles, nearly 1600 feet) across that are in Earth's vicinity. Of those, 860 are a kilometer across (.62 miles, almost 3300 feet across). Imagine what kind of damage those asteroids (between 10 and 22 times the size of 2012 DA14) could do.
But there are still massive space rocks undiscovered. In fact, 2012 DA14 was only discovered last February. Astronomers say that an asteroid that size collides with the Earth on average once every 764 years. According to a study released in September 2011, NASA scientists believe that only about a 1,000 asteroids are left to be found that measure a kilometer or more in diameter.
Only...
But these numbers are just averages and estimates. And space is vast. And full of large, extremely fast, and constantly moving objects...
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