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Trojan asteroids.

By 1906, no fewer than 587 asteroids had been spotted (thanks to Wolf's photographic technique-see 1891) and had their orbits calculated.

In 1906 Wolf discovered an asteroid that moved unusually slowly and must therefore be unusually distant. In fact it moved in Jupiter's orbit at the outer extreme of the asteroid belt, keeping step with Jupiter at a distance of 60 degrees.

This meant that the Sun, Jupiter, and the new asteroid were located at the vertices of a vast equilateral triangle. Lagrange (see 1788) had shown back in 1772 that such an arrangement was gravitationally stable, but this was the first case of such a gravitational triangle that had been actually found in space.

Wolf named the asteroid Achilles, after the hero of Homer's Iliad, the tale of the Trojan War. In giving an asteroid with an unusual orbit a masculine name, he followed the precedent of Witt (see 1898).

Other asteroids were eventually discovered that accompanied Achilles in its triangular position, and still others at a point 60 degrees from Jupiter in the other direction, so that there were two equilateral triangles adjacent to each other. All were named after various heroes of the Trojan War, so that they could be lumped together as the Trojan asteroids. The position at the third apex of a triangle where the other two are occupied by larger bodies is now called the Trojan position.

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Author:Asimov, Isaac
Publication:Asimov's Chronology of Science & Discovery, Updated ed.
Article Type:Reference Source
Date:Jan 1, 1994
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