Western Slope Skies 12/20/13

Dec 20, 2013

As the holidays approach, the days shorten, bringing with them our glorious Western Slope night skies.  Joining us to celebrate the season is a brilliant cluster of stars, called the Pleiades, or Seven Sisters. 

Rising on our eastern horizon, the Pleiades first appears as a cloud-like thumbprint.  As your eyes adapt to the darkness, you’ll be able to pick out point-like stars, as many as six or seven. 

Throughout history, different observers have used their own discretion with naming the cluster.  Hence, the popular “Seven Sisters” designation.  (Subaru, which is the Japanese name for the Pleiades, uses six stars in their car logo.)

With binoculars or a small telescope, the main points become luminous diamonds on a field of hundreds of fainter stars. 

Star Cluster Pleiades, captured with a 5" telescope and DSLR camera in November, 2012
Credit Art Trevena/Black Canyon Astronomical Society

This luminous appearance, or “nebulosity,” more apparent in larger telescopes and photos, is from blue-white starlight reflecting off dust.  The light from those stars left 440 years ago to shine for us today.

An open star cluster, like the Pleiades, can be thought of as a “family” of stars.  Loosely gravitationally bound, and age-related, open star clusters can stay together for tens to hundreds of millions of years.  Astronomers believe that many stars, including the Sun, were born in open clusters that were eventually torn apart by gravitational forces within the galaxy.

So take a break from the seasonal hustle and bustle, go out, find the Pleiades and give yourself the opportunity to revel in our night skies.