A recently discovered small asteroid with the catalog name 2011 MD is generating lots of interest in the professional and amateur astronomy community due to its upcoming close encounter with the Earth Tuesday Australian time. It will pass only 12,000 kilometers above the Southern Atlantic Ocean near the coast of Antarctica at around 3 am AEST Tuesday morning (28 June 2011). By astronomical standards, this is a very close encounter.
What is unusual about this 2011 MD’s encounter with the Earth is that the astronomy community has been alerted to it in advance of the close encounter. Asteroids this small are very difficult to detect when they are far from the Earth. Most asteroid hunting telescopes look at visual wavelengths (like our eyes see). The further the asteroid is from the Earth, the fainter it will be. This means that small asteroids that have close encounters with the Earth are usually only detected just after a close encounter with the Earth.
Asteroid 2011 MD was discovered by the LINEAR near-Earth object discovery team observing from Socorro, New Mexico in the United States. The asteroid 2011 MD is in a very Earth-like orbit which led some astronomers to propose that it was part of a rocket body. This has almost been ruled out through looking at when it last visited the Earth. There is a possible close encounter in 1962 (meaning that it may still turn out to be a rocket body) which hadn’t been eliminated at the time of writing this post. There is no chance that the asteroid will strike the Earth on this encounter. More information about this asteroid can be found at NASA’s Near Earth Object Program website. An interactive orbit applet can be found here on the JPL Small-Body Database Browser.
At peak brightness, this asteroid would be briefly visible to visual observers using medium sized amateur telescopes (say an 8 inch telescope). If you are interested, you will need to own a decent star chart program to calculate where to look for your specific location. It’s closeness to the Earth means that it’s apparent location in the sky will vary dramatically for observers at different geographical locations. According to Sky & Telescope magazine, it will be visible from Australian locations in the hours leading up to closest approach (look around Midnight on Monday 27 June 2011).
