Feb. 23, 2012, started out as a fairly normal Thursday for astronomers at the La Sangra Sky Survey in Spain.
That soon changed when they made the discovery of asteroid 2012 DA14. It was quickly classified as one of those objects that strikes fear into the heart of any astronomer -- a near-Earth asteroid!
Further studies over many weeks revealed its orbit would bring it very close to Earth. An asteroid of DA14's size -- around 45 meters (150 feet) in diameter -- would pack quite a punch if it was on target.
Fortunately, this time we have avoided an impact event -- 2012 DA14 will pass about 27,700 kilometers (17,000 miles) from the surface. That's close in astronomical terms and using my own personal scale of "asteroid closeness," it's a bit of a butt-clencher.
At this distance, it will come closer than geosynchronous satellites, but thanks to a high degree of scrutiny, we know it will sail harmlessly past without denting anything.
If we were less lucky on this occasion, we can look to a couple of events in recent geological history that are thought to have been caused by impacts from asteroids of comparable size.
The first took place in 1908 over Tunguska, Siberia, when an asteroid is believed to have exploded near the surface, flattening millions of trees over a remote area of at least 2,000 square kilometers. The other was an impact in the Arizona desert around 50,000 years ago, the so-called Meteor Crater that measures a staggering mile in diameter.
Clearly, if 2012 DA14 were to hit us, and if it slammed into a metropolitan area, it would be an impact of catastrophic proportions with the potential to cause millions of deaths (assuming no evacuation plan was put in place).
This time round, however, and during future predicted orbits of 2012 DA14, no impacts will occur.
What this flyby will do, however, is give sky watchers a great opportunity to watch one of these rare and historic close passes of an interplanetary visitor. Its closest approach will bring it over Indonesia at 19:25 UT (2:25 p.m. ET) on Friday, Feb. 15, but amateur astronomers from many parts of the world -- principally Eastern Europe, Asia and Australia -- will get a chance to glimpse it on its way past.
The tiny dot of sunlight reflecting off the asteroid will shine at magnitude 7.2, meaning it will be just beyond naked eye visibility. But binoculars will show it nicely.
It is difficult to explain exactly where and when to look, since its exact whereabouts in the sky will depend on where you are on Earth. Check out Heavens-above.com to find out exactly where to look in your sky. When you get out there and look into the sky with binoculars or telescope trained in the right direction, look for a "star" slowly moving against the background stars.
If you aren't lucky enough to be in the right part of the world, or your skies aren't clear, there are several observatories online that will be streaming the event live:
Happy asteroid hunting!