
Lyra and M57
by Greg Eans, July, 2005 Last Month I highlighted the constellation Hercules, the fifth largest in the sky, and the Messier object M13, one of the finest globular clusters in the northern hemisphere.
Now that summer has arrived, the westward motion of the stars against the celestial sphere brings a new visitor to our highlighted area above the trees in the backyard:
Lyra. 
On the order of size, the constellation Lyra ranks a mere 52nd among its 87 peers in the night sky, just larger than Crater and a notch below Lepus but, it contains the 5th brightest star in the heavens, Vega, one of the trio of stars that make up the Summer Triangle.
A wonderful object tucked between Beta and Gamma is the planetary nebula, M57, the Ring Nebula (NGC 6720). What you are seeing when viewing M57 is a very old star that has ejected its outer layers. The expanding gas that has been blown off this star forms a shell of various shapes as it progresses outward, leaving the hot, inner regions exposed. Its temperature can be as hot as 1,000,000º Kelvin, and this is the initial stage of its collapse into a white dwarf. Our Sun will meet the same fate in some 5 billion years.

In July,
Mars rises in Pisces about an hour after midnight and is 84% illuminated. It will continue to get bigger and brighter over the next few months. Jupiter will set around 11 pm toward the end of the month. Venus and Mercury are very close at the begining of July, as little as 1º on July 1. Saturn will not be visible for long after evening twilight. Look for the planet with binoculars in the WNW just after sunset, below Venus and Mercury.
The Moon in July

Greenville Clear Sky Clock