Monday, July 29, 2013

Hercules Isn't Too Bright

This month is all about the guys in the sky. First we'll talk about Hercules and later in the month we'll explore Ophiuchus the Serpent Wrestler.
As strong as Hercules was, he sure has some dim stars in the sky. Hercules is not an easy guy to find up there - his brightest stars being only of third magnitude. The best way to find Hercules is to look for the keystone, or four sided figure that makes up his body. Hercules is said to be kneeling. Unfortunately for him (and our imagination), he is kneeling upside-down. Look for the brighter constellations around Hercules - Draco is above, Lyra to the left, Corona Borealis to the right, and Ophiuchus the Serpent Charmer below him.

The brightest star in Hercules is Ras Algethi which means, in ancient Arabic, "Head of the Kneeler." This must be some acrobatic kneeler standing on his head! The star is a red supergiant 600 times the diameter of our sun. that varies in brightness. Aim a small telescope at Ras Algethi and you will discover that it is really two stars in one.

The most interesting feature in the figure of Hercules is fuzzy area in the sky called M 13. M 13 is a globular cluster - a cluster of around 300,000 stars - the brightest of its kind in the northern skies. M stands for Messier object, and these are nebulae and galaxies charted by the French astronomer Charles Messier. This cluster is number 13. You can see M 13 with the naked eye but try viewing it through some binoculars to achieve a sparkling effect.