Passing in the Night

An object designated 2010 AL30 was discovered on January 10, earlier this week, headed in our direction at high speed. It zipped by yesterday on January 13 at a distance of about 130,000 kilometers -- roughly a third of the distance from the Earth to the Moon. The object was discovered by the MIT-affiliated, NASA-funded LINEAR project. LINEAR is an acronym for the LIncoln Near Earth Asteroid Research program, run by MIT's Lincoln Laboratory.


You can see on the fine print on the image that it was constructed from "stacking" a series of ten images to obtain this result.

When I wrote the first paragraph above, I had some indecision about writing 126,000 versus 130,000 kilometers, because this was after all just a rough estimate. Note that my indecision represented a distance spanning a goodly fraction of the width of North America, for a chunk of space debris about the size of a moderate living room. This thing was tiny -- but still moving so fast that it would potentially have been unpleasant if it had hit the Earth.

I have no idea of the composition of 2010 AL30, but it is not much smaller than the object which is thought to have precipitated the Tunguska Event. The Tunguska precursor object, believed to be "a few tens of meters" in size, did not actually make it all the way down to the ground, but disintegrated and in so doing caused an impact explosion in the atmosphere that was a thousand times more powerful than the nuclear weapons used at Hiroshima and Nagasaki. It flattened trees over 2,150 square kilometers, and would certainly have devastated a city.

Research programs such as LINEAR are part of a loose international association of asteroid monitors called Spaceguard. The American objectives were to catalogue 90% all Near Earth Objects (NEOs) larger than 1 km in diameter by 2008, with a proposed follow-on program whose objective would be to detect 90% of all near-earth asteroids 140 meters and larger by 2028.

NOTE - The above photo was lifted from the blog of the observer team of the Remanzacco Observatory in Italy.