By Mike P. Usher
Face west and look up; way, way up and spot the bright blue-white star Vega very nearly at the zenith tonight. If you can see anything at all you will see Vega, one of the brightest stars in the sky. It’s also the brightest star in the constellation Lyra, the lyre, which includes a small, but distinctive parallelogram just above Vega. For some completely mysterious reason a large number of people refer to Vega as the north star, which is odd as the star is quite some distance (over 50 degrees) away from the pole. However in the very far distant future Vega will become the pole star as our home planets axis slowly wobbles in that direction.
Directly between Ophiuchus and Draco, constellations discussed in recent columns, lies the constellation Hercules. Like all of its neighbors Hercules is an ancient constellation, one of the original 48 described by the second century astronomer Ptolemy. In mythology, Hercules was one of the most famous of all Greek heroes and was indirectly responsible for the placement of a number of constellations into the sky – such as the nearby Draco, whom he killed.
Although Hercules is one of the larger constellations, it contains no particularly bright stars. It does however have an asterism known as the keystone, the four stars forming a rough square in the center. Also of some slight interest is the Sun is moving towards a spot in Hercules fairly close to Vega (the solar apex) at a modest 10 miles per second. Now when someone asks you the rhetorical question “where are we all headed?”, you have an answer!
Bright deep sky objects for binoculars are hard to come by in this section of the sky, but you can not ignore one of the wonders of the northern sky – M13 the Great Cluster in Hercules. At magnitude 5.9 it is theoretically bright enough to be seen by the naked eye, but with binoculars it’s easy. (It might be best to wait a couple of days until the bright Moon is not in the sky.) If you want to see what 300,000 to 500,000 stars look like all crammed together in a ball only 140 light-years across, this is the one to see. Unfortunately, the light is smeared into a fuzzy blob; you would have to crank on some serious power in a large amateur telescope to see individual stars.
Just so you know, Mercury will be making a quick appearance in the latter half of August in the constellation of Cancer. Look for an orange-red star in the east about a half hour before sunrise.
See you next time!
Mr. Usher is President of the Everglades Astronomical Society which meets the second Tuesday each month during the summer at 7:00PM in the Books-A-Million, at the Mercato, Naples.