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February 27, 2013

The brilliant planet Jupiter stands above the two most prominent features of the celestial bull right now. Taurus’s V-shaped face is to the lower left of Jupiter, highlighted by his “eye,” the orange star Aldebaran. And the bull’s sparkly shoulder is a little farther to the lower right of Jupiter: the Pleiades star cluster.

The Pleiades contains hundreds of stars, but only a few of them are bright enough to see with the unaided eye. Most people see six, while those with dark skies and good eyesight may see eight or more.

The brightest of the Pleiades is Alcyone, and not surprisingly, it’s quite impressive. It’s several times heavier than the Sun, and hundreds of times brighter, so it’s easily visible even though it’s more than 400 light-years away.

Alcyone also spins faster than the Sun — an indication that it’s a good bit younger. As a star ages, its magnetic field acts as a brake, slowing its rotation. The Sun spins quite slowly, which is one indication of its age.

Alcyone spins so fast that it throws some of the hot gas from its surface out into space. The gas forms a glowing disk around the star. Analyzing the light from this disk reveals details about the star’s composition.

Alcyone connects the bowl and handle of the dipper formed by the Pleiades. The cluster is well up in the southwest as night falls, and slides down the western sky later on. The Pleiades and its bright companions set in the wee hours of the morning.


Script by Damond Benningfield, Copyright 2012

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