An asteroid of a similar size to a rock that exploded above Siberia in 1908 with the force of a thousand atomic bombs whizzed close past Earth on Monday, astronomers said on Tuesday.
2009 DD45, estimated to be between 21 and 47 meters across, raced by at 1344 GMT on Monday, the Planetary Society and astronomers' blogs reported.
The gap was just 72,000 kilometers, or a fifth of the distance between Earth and the Moon and only twice the height of satellites in geosynchronous orbit, the website space.com said.
The estimated size is similar to that of an asteroid or comet that exploded above Tunguska, Siberia, on June 30 1908, flattening 80 million trees in a swathe of more than 2,000 square kilometres.
Interesting enough this asteroid not identified to Saturday and hence an unknown quantity.
This has been recently discussed in Russian scientific literature eg Dorman 2008,and inthe Russian press.
MOSCOW. (Andrei Kislyakov for RIA Novosti) - Humankind has created a major problem: space debris, now threatening long-term space travel.
So much space junk has accumulated that the international community must take urgent action to prevent major accidents at high altitude and on Earth.
Space debris denote manmade objects in orbit around Earth that no longer serve any useful purpose but which endanger operational satellites, primarily manned spacecraft. In some cases, space junk may threaten Earth during reentry because some fragments do not burn up completely and can hit houses, industrial facilities and transport networks.
Right now, 40 million fragments of space debris weighing several thousand metric tons circle Earth. In mid-February, the United Nations Office for Outer Space Affairs (UNOOSA) reaffirmed the importance of guiding principles to prevent the formation of space debris for all nations.
On December 17, 2007, the UN General Assembly passed its Resolution 62/101 stipulating recommendations on enhancing the practice of states and international intergovernmental organizations in registering space objects.
Concerted international efforts and the dangers of hypothetical space debris crashes will make it possible for humankind to cope with this problem in the long term. However, Earth is still threatened by asteroids and various comets.,,
It is common knowledge that a new comet annually enters the solar system. Judging by the average lifespan of comets, about 3,000 of them fly through the solar system each year. In reality, astronomers register only 25 comets.
Scientists seem to have solved this contradiction. This discrepancy between theoretical calculations and practical observations is explained by the fact that many comets cannot be detected by optical systems.
It appears that such objects are created when a celestial body's nucleus loses most of its water due to evaporation. This makes new comets too dark to be observed through optical telescopes and a potential threat to planet Earth.
The latest studies of terrestrial and lunar craters show that most of them were gouged by comets. This news is not very encouraging either.
Of further interest Nasa's chief climate catastrophe theorist was buried in snow at a global warming protest in Washington.
Fortunately with Nasa unavailable we have someone who understands the mathematics a little better.
Nico Marquardt used telescopic findings from the Institute of Astrophysics in Potsdam (AIP) to calculate that there was a 1 in 450 chance that the Apophis asteroid will collide with Earth, the Potsdamer Neuerster Nachrichten reported.
NASA had previously estimated the chances at only 1 in 45,000 but told its sister organisation, the European Space Agency (ESA), that the young whizzkid had got it right.
The schoolboy took into consideration the risk of Apophis running into one or more of the 40,000 satellites orbiting Earth during its path close to the planet on April 13 2029.