Almahata Sitta: a unique meteorite

In December 2008, researchers from the University of Khartoum discovered a very special meteorite in the Sudan desert. This is an account of that amazing discovery.

Our story begins on October 6, 2008, when astronomer Richard Kowalski was working with the telescope at the Mount Lemmon observatory in Arizona. His goal: determine the existence of asteroids that might cross the orbit of the Earth and conceivably collide with our planet.

That night, Professor Kowalski discovered a seemingly harmless-looking asteroid, which was designated 2008 TC₃. But after a few calculations, he realized that this asteroid would collide with the Earth in less than twenty hours.

At that point, the world’s community of astronomers was alerted. They all got to work on refining the observations and on trying to predict exactly where this hunk of celestial stone would fall. In the hours that followed, over 500 different observations were carried out on the asteroid. The astronomers were sure of one thing: the asteroid would be falling over the Sudan. However, a number of them believed that the object would disintegrate entirely in the layers of the Earth’s atmosphere.

Impact

As expected, on October 7 at 2:46 a.m. the asteroid dove into the terrestrial atmosphere. The crew of an airliner traveling from Johannesburg to Amsterdam observed a fireball in the sky. A few witnesses on the ground in the Sudan desert also observed the phenomenon. One observer even filmed the trail of dust that the asteroid’s passage left in the atmosphere.

A treasure fallen from the heavens

In December 2008 a first meteorite fragment was discovered in the sands of the Sudan’s Nubian Desert, close to a train station called Almahata Sitta – “Station Six” in Arabic – and thus the meteorite was named.

To date, more than 600 fragments have been found, weighing a total of just under eleven kilograms.

Analyses of the fragments indicate three types of different meteorites, which suggests that asteroid 2008 TC₃ was an agglomeration of three distinct bodies that stuck together as a result of one or more collisions in the distant past.

The story of Almahata Sitta is special, because this was the first time that debris from an asteroid was collected after it was observed in space. The study of this meteorite is still going on. Among other things, it’s providing us with information about the nature and formation of asteroids and meteorites.

Come see a piece of this meteorite and learn more about it during "A Unique Meteorite" exhibition at the Planétarium until July 20.