Most people will be aware that there are numerous objects hurtling through our universe and that from time to time many of these come into the vicinity of planet Earth. These objects may be man made such as satellites and rocket debris and can also be naturally occurring such as comets and asteroids. Some of these can pass fairly close by and in the history of our planet it has been shown that some of the naturally occurring comets and asteroids have collided with the Earth with devastating consequences. It is generally considered that with the technology we have available today the danger of any earthbound comet would be detected long before it got close to us. However the events of last Friday proved this is not a foregone conclusion and that a surprise can still occur.
Many people may have missed the news but an asteroid was detected passing less than 9000 miles from the Earth on Friday 6 November and it was only 15 hours before this happened that the comet was actually detected. The asteroid was first picked up by researchers at the University of Arizona as part of their Catalina Sky Survey and following this was detected by the Minor Planet Centre in Cambridge Massachusetts. The asteroid was then picked up by the National Aeronautics and Space Administration (NASA) and its trajectory plotted.
The 23 foot wide asteroid has been christened 2009 VA and at its closest it was only 8700 miles from the Earth. This is 30 times closer than the Moon which lies approximately 250,000 miles from the Earth and it was the third closest approach of an asteroid ever recorded. However it is not considered that the asteroid would have made much of an impact and in actual fact it probably would have burned up in the Earth’s atmosphere long before it reached the ground.
However the more worrying aspect of the story is the fact that it was only detected 15 hours before it passed the Earth. This demonstrates that there are still objects out there that we know little about and shows how close they can approach before actually being detected. Although 2009 VA actually posed little threat, a larger asteroid could have potentially devastating consequences if it were to collide with planet Earth.
NASA was tasked by Congress with identifying at least 90% of the asteroids that are considered to pose a threat to our planet by 2020. They were assigned the task in 2005 and initially estimated there were around 20,000 dangerous comets and asteroids, with those that are 460 feet or greater in size being considered a risk. To date scientists have accurately located around 6000 of these and the scheme which is known as the Near-Earth Object Program continues.
However the passing of 2009 VA shows how difficult this task will be. For an asteroid to get so close to the Earth without being detected is not something that should be taken lightly. NASA monitored a 100 foot asteroid in March this year as it passed around 45,000 miles from the Earth. An asteroid of similar size crashed into planet Earth in 1908 although it landed in a remote part of Siberia. The impact however devastated an area 1,200 square miles in size and if such an object landed near an area of dense population there would be severe consequences.
The NASA project is therefore important and if an early warning of an imminent strike was given this could greatly reduce the human consequences involved. 2009 VA was a lesson that the task of identifying near earth comets and asteroids is not an easy one although the hunt will go on.
