This week we explore the the constellation Corona Borealis, the Northern Crown. Located in the Summer night sky between Bootes to the west and Hercules to the east, Corona Borealis is the crown made by the supreme goldsmith, Hephaestus, at his underwater smithy, worn by Ariadne at her wedding, and upon her death, placed in the heavens by Dionysus to immortalize his love for her.

The seven stars that make up the crown are not terribly bright, except for Gemma, or Alphecca (alpha Coronae Borealis), which is a 2.2 magnitude star 75 light years away. There are several double, or binary, stars in Cornona Borealis, those bound gravitationally to each other, and a few variable stars whose brightness changes periodically over time.


There are only a few deep sky objects in this constellation -- a few small, faint irregular galaxies, more interestingly, a cluster of galaxies known as -- of course -- Corona Borealis Galaxy Cluster. 

This group is very faint but quite spectacular for those with the proper equipment. 
The cluster is comprised of over four hundred galaxies in an area of about one degree (the width of your thumb). The galaxies are extremely distant, over a billion light years away, and consequently are very faint. The brightest of the group are 16.5 visual magnitude.

Closer to home, the Mars Global Surveyor as it orbits Mars, sent back to Earth the first ever picture of Earth from Mars.  Beautiful in crecent, the Earth is seen also in the same view with much distant Jupiter.

This is shaping up to be a great weekend, with fair weather, a holiday Monday, and near a new Moon, giving us dark and clear night skies.

Enjoy and keep looking up!