A star with dual allegiances teams up with the Moon and the planet Venus this evening. The three objects form a compact triangle low in the west shortly after sunset. Venus is the dazzling "evening star" to the upper left of the Moon. The star is about the same distance to the upper right of the Moon.
The star is El Nath -- a name that means "the butting one." It's at the tip of one of the horns of Taurus, the bull.
Officially, El Nath is within the borders of Taurus. In fact, it's the bull's second-brightest star. Back when the classical constellations were drawn, though, there were no borders between constellations -- only connect-the-dots patterns of stars that outlined pictures.
So the people who drew the constellations weren't bound by any particular rules. If a star could help complete more than one star picture, then there was no reason not to reuse it.
And that's what happened with El Nath. It's in perfect position to serve as the tip of the bull's horn. But it's also in perfect position to complete the picture of the next constellation over -- Auriga, the charioteer. So El Nath does double duty.
The star itself is a giant -- it's bigger, heavier, and hotter than the Sun. It's also a good bit brighter than the Sun, so it puts on a good showing in our sky even though it's 130 light-years away -- where the bull butts into the chariot driver.
We'll have more about Venus and the Moon tomorrow.
Script by Damond Benningfield, Copyright 2010