Toutatis makes a pass

On September 29, an asteroid named Toutatis, 4.6 km by 2.4 km, had a close encounter with the earth. Astronomers assert that this will be th...

On September 29, an asteroid named Toutatis, 4.6 km by 2.4 km, had a close encounter with the earth. Astronomers assert that this will be the closest known pass of a very large space rock anytime this century.

The asteroid was first noticed 15 years ago in January 4, 1989. C. Pollas, an astronomer, was scrutinising the photographic plates that held the astronomic observations of Jupiter’s faint satellites by Alain Maury and Derall Mullholl of France. He drew the attention of the two to streaks that appeared in every plate. They concluded the streaks were the trail of an asteroid. They named it Toutatis after a Celtic/Gallic God. (One finds this name in the comic series Asterix, set in ancient Gaul. Asterix and his compatriots are fearless, yet they have one fear. They are afraid the sky might fall on their heads. They find their guardian angel in Toutatis).

The asteroid has a strange shape. It looks like two blobs, one of them double the size of the other, fused at the centre to resemble a dumbbell. Scientists have no explanation for its unconventional shape and spin. Its path ranges from just inside earth’s path to the main asteroid belt between Mars and Jupiter. It has a periodicity of nearly four years. It came close to earth on December 8, 1992; November 29, 1996; October 31, 2000.

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On September 29, 2004, the asteroid came closest to the earth, at a distance of 15,649,834 km. That is rather too close by cosmic standards. Astronomers consider it close enough to cause concern. Specially now when space is littered with all sorts of manmade objects! If the asteroid skids against one of them and changes its course even by a very small angular deviation, would it be in line with the earth’s orbit?

Nobody knew about asteroids till 1772. In that year, Johann Bode, a German astronomer got a strange idea. Was there any cosmic order in the placement of the planets? He prepared a table that showed the distances of the planets from the Sun, taking the distance of the earth from the Sun as 10.

Looking at the figures, he had a brainwave. There should have been a planet between Mars and Jupiter. It should be at distance of 24 by the scale he had used. Astronomers set out on the hunt. They studied the gap between Mars and Jupiter. Finally a Sicilian astronomer Giusepi Piazzi noticed a very small body, just 800 km in diameter, in orbit round the sun. It was at a mean distance of 27.7. Close enough to the figure 28 set down by Bode. He called it Ceres. Another small object, just about 170 km diameter, was found in the same space. Its mean distance too was 27.7. Soon after, two more tiny objects in orbit were spotted. The four formed the first batch of asteroids Ceres, Pallas, Juno and Vesta. Since then, more than 2000 of such bodies have been discovered. They are now called asteroids.

Asteroid Toutatis is moving away from the earth. Astronomers are now poring over the data collected to know more. For them, September 29 provided a golden chance to pry further into the secrets of the asteroids.