Posted by: TheAuthor | 05/12/2010

2004 MN4

Friday the 13th. A day you may believe to be an unlucky day. A day you get bad news, knock over a vase or Jason Voorhee’s comes rampaging.

However, for some it’s not a day to watch out for. Perhaps it’s your birthday, or your going to the football, maybe someone’s coming home from a trip away. How about watching something incredible, something the likes of which is rarely seen? – especially with the naked eye.

Keep your evening free on April 13th (A Friday) 2029, This natural event will attract millions of people to go outside and look up. There, spectators will see a spot of light, not too dissimilar to a satellite, sailing across the sky – faster than a satellite and brighter than a star. What am I talking about? Well, it’s an asteroid called  ‘2004 MN4′. This asteroid is roughly 320 metres wide. “That’s big enough to punch through Earth’s atmosphere, devastating a region the size of, say, Texas, if it hit land, or causing widespread tsunamis if it hit ocean” – Paul Chodas, NASA.

2004 MN4 was discovered on 19 June 2004 by Roy Tucker, David Tholen and Fabrizio Bernardi of the NASA-funded University of Hawaii Asteroid Survey (UHAS), from Kitt Peak, Arizona, and observed over two nights. On 18 December, the object was rediscovered (after being lost) from Australia by Gordon Garradd of the Siding Spring Survey, another NASA-funded NEA survey. Further observations from around the globe over the next several days allowed the Minor Planet Center to confirm the connection to the June discovery, at which point the possibility of impact in 2029 was realized by the automatic SENTRY system of NASA’s Near-Earth Object Program Office.This prediction was made with sparse tracking data, a collision couldn’t be ruled out nor confirmed until further data was collated. On Christmas Eve 2004, astronomers at NASA’s Near Earth Object Program office calculated a 1-in-60 chance that ‘2004 MN4’ would collide with Earth. The impact date: April 13, 2029.

As it happens in March 2004 astronomers found pictures of the asteroid taken, unwittingly, three months before its official discovery. The extra data ruled out a collision between ‘2004 MN4’ and Earth in 2029. In January 2004, a team of astronomers led by Lance Benner of JPL pinged ‘2004 MN4’ using the giant Arecibo radar in Puerto Rico. (Coincidentally, the Arecibo dish is about the same size as the asteroid.) Echoes revealed the asteroid’s precise distance and velocity, “allowing us to calculate the details of the 2029 flyby,” says Giorgini, who was a member of the team along with Benner. No Armageddon and no chance of a ‘Deep Impact’ either, not this time.

‘2004 MN4’ will fly past the Earth at a height of only 18,600 miles above the ground. As a comparison, a geosynchronous satellite typically orbit’s at 22,300 miles. “At [it’s] closest approach, the asteroid will shine like a 3rd magnitude star, visible to the unaided eye from Africa, Europe and Asia – even through city lights” says Jon Giorgini of JPL. “This extremely rare.Close approaches by objects as large as 2004 MN4 are currently thought to occur at 1000-year intervals, on average.”

More data is needed to forecast 2004 MN4’s motion beyond 2029. “The next good opportunities are in 2013 and 2021,” Giorgini says. The asteroid will be about 9 million miles (14 million km) from Earth, invisible to the naked eye, but close enough for radar studies. “If we get radar ranging in 2013, we should be able to predict the location of 2004 MN4 out to at least 2070.”

This object is the first to reach a level 2 (out of 10) on the Torino Scale. According to the Torino Scale, a rating of 2 indicates “a discovery, which may become routine with expanded searches, of an object making a somewhat close but not highly unusual pass near the Earth. While meriting attention by astronomers, there is no cause for public attention or public concern as an actual collision is very unlikely. New telescopic observations very likely will lead to re-assignment to Level 0 [no hazard].”


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