The skies belong to everyone, part five: Stars

Posted by David Eicher
on Friday, May 6, 2011

So you bought a telescope to look at everything the universe has to offer. You’ve explored the various carters and maria of the Moon plus all the planets and comets.  What should you look at next?

Merope is a member of the Pleiades star cluster in the constellation Taurus. Photo credit: Kfir Simon
Looking beyond the family of the Sun, we take a long step into deep space. Stars, like people, come in many sizes, types, and ages. The majority of stars, in fact, are not alone. Just as the Sun has planets, some stars have other stars. Many of these double star systems are conveniently placed for small-telescope observing. Albireo (Beta [ß] Cygni), for example, is the bright star marking the beak of Cygnus the Swan — a prominent constellation in summer and fall skies. Small telescopes quite easily show that this star, a single point of light to the naked eye, is made up of a bright yellowish star and a slightly dimmer blue companion. These stars orbit a common center of mass and travel together through space. The inky black gap between Albireo’s two stars is so wide, you could fit 10 solar systems within it.

Stars vary in behavior. Some change their brightness or size over time. These are variable stars, and they, too, are within the capability of backyard telescopes. Observing variable stars is rather tricky as you must adjust your eyes to the subtle differences in various stars’ brightnesses. But for a start, look at the star Mira (Omicron Time Ceti) each time you’re out. It’s marked on Astronomy magazine’s StarDome and virtually all star atlases. You may not see a star where Mira is supposed to be — if so, Mira is near minimum brightness. Or you may see a bright star precisely where Mira is shown on the map. If so, keep watching it. Over a period of several weeks, Mira will fade to below naked-eye visibility, and then weeks later will rise back to where you can see it. With binoculars or a telescope, you can follow Mira’s entire cycle of variability.

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