It is an event, as it does not occur every day. On Friday, the 15th February, is in the early evening rush past a 45 meter large asteroid in extremely short distance to the Earth. At the time of its closest approach distance is only 28 000 kilometers. That's far enough away to rule out a collision definitely can. After all happened the rocks our home planet but within the orbit of geostationary satellites. That an asteroid of this size so close to fly past the earth, since the beginning of the systematic search for near-Earth objects in the 1990s has not yet occurred. Is correspondingly great interest in the event, which can already be tracked with a good pair of binoculars or a simple telescope.
Although the asteroid 2012 DA14 does not approach the first time the earth was known until a year ago none of its existence. He was discovered by amateur astronomers who are looking with a small telescope in southern Spain for small objects in low Earth orbits. On the night of 22 on the 23th February 2012 they came across a hitherto unknown object moving at great speed.
Subsequent observations confirmed that it is an asteroid which revolves in a similar orbit around the Sun as the Earth. This regular encounters are inevitable. An approach such as now, however, there would be no more for decades, Donald Yeomans of NASA's Jet Propulsion Laboratory said last week at a press conference. The reason is the distraction of the asteroid in the gravitational field of the earth experienced.
A reason to feel safe, but it's not. According to estimates by scientists there are in low Earth orbits about 500 000 asteroids of similar size like 2012 DA14. According to Yeomans every 40 years is likely to have a similarly close flyby of the Earth and every 1200 years with a twist.
The consequences of such a collision would indeed regional. Underestimated but they are not yet. The so-called Tunguska event shows from 1908. In a wooded and sparsely populated region of Siberia at that time an asteroid or comet exploded in the atmosphere and bent over an area of 2000 square kilometers in rows around the trees. The force of the explosion is still under discussion. One assumes, however, that the exploding body had a similar size as 2012 DA14.
Until now, no asteroid is known that in the foreseeable future is a threat to the Earth, says Detlef Koschny, of the European Space Agency ESA, the "Near Earth Object" program for "Space Situational Awareness" is derived. Concerns caused him, however, that something might come to us, what we do not know. Because of the estimated 500,000 asteroids in near-Earth space, which are of similar size as 2012 DA14, we have discovered to date less than one percent.
This situation will not change much for the time being. Because the space agencies lack the money, in order to capture this large population of relatively small asteroid. While NASA is initially limited to a systematic search for objects concentrates, which are greater than 140 meters, the ESA is another way. With a yet to be developed system of automated telescopes they will detect asteroids like 2012 DA14 at least three weeks before closest approach. Threatens a collision would at least time to evacuate the affected region.
Post a Comment