2017, July: Venus


Venus rises about 2.5 hours before the sun during July, sparkling low in the predawn sky, far outshining all the stars in the sky.

During July, Venus moves through the Taurus region that has bright stars and star clusters.  On July 14, Venus moves past Aldebaran.  The closest approach is about 4 degrees.

The Binocular View

More striking is the star cluster near Venus and Aldebaran: Hyades.  The Hyades cluster is about 2.5 times farther away than ruddy Aldebaran.  Through binoculars, Venus, Aldebaran and the jewel-like stars of the cluster sparkle against the black velvet of the  predawn sky. Several dozen stars can be seen.

To the unaided eye, the Hyades resemble a check mark or a letter “V” if Aldebaran is included.

Clusters, like the Hyades, are used to refine distance measuring techniques as well descriptions of the lives of stars.  These clusters are thought to form at approximately the same time.  Stars that burn their nuclear fuels faster convert into other stellar forms sooner, such as red giants and red super giants.  From these stellar models, the estimate of the sun’s total lifespan is about 10 billion years.

Over time these clusters break apart; the gravitational forces between the stars are not strong enough to keep the cluster together.  The stars go their own way in their orbital path around the galaxy.

Our sun was likely formed in such a cluster and is now a lone star since it has gone into its own orbit around the Milky Way galaxy.

On the morning of July 20, the crescent moon again appears with Venus.  The pair is separated by about 3.5 degrees.

For more information about sky watching events:

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