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Fire and Water

December 3, 2011

The ancient elements of fire and water sit side by side low in the southern sky at this time of year.

Fire is represented by the constellation Fornax, the furnace. French astronomer Nicolas Louis de Lacaille drew the constellation after traveling to the southern hemisphere.

The stars of Fornax aren’t all that fiery. Instead, the constellation is famous for its galaxies. It harbors a small galaxy — the Fornax dwarf — that orbits the Milky Way.

Far beyond the Fornax dwarf is a cluster of galaxies. The Fornax cluster contains the beautiful barred spiral galaxy NGC 1365, which looks like a backward letter S. It’s 60 million light-years away.

East of Fornax is a constellation that represents water: Eridanus, the river. In mythology, Eridanus was the river that Phaethon fell into after trying to drive the Sun chariot across the sky. But in many cultures, Eridanus also represented real rivers, such as the Nile and the Euphrates.

Eridanus is a long, winding constellation that looks like its namesake — if you can see it. Most of its stars are faint, but at the southern end of the river is the brilliant blue star Achernar. It’s so far south, though, that most of us in the United States can’t see it.

But Eridanus has another famous resident that’s a little easier to pick out. Epsilon Eridani, though dim, is one of the closest stars that resembles the Sun. It’s just ten and a half light-years away, marking a near neighbor in the long river in the sky.


Script by Ken Croswell, Copyright 2011


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