The constellation Hercules isn't as obvious as many of the other summer constellations. It has no bright stars - the brightest, Beta Herculis, shines at a middle-of-the-road magnitude +2.78 - and its most famous stellar object, globular cluster M13, is a faint, watered-down magnitude +5.9. Anything that faint can only be spotted from a dark location, well away from city lights. Hercules hardly seems worth bothering with, but there's more going on there than meets the eye.

Two stars in Hercules - Mu Herculis and GJ 661 - are each less than 30 light years from us, which, in cosmic terms, is just across town. Seven stars in the constellation are now known to have planets in orbit about them. And the solar apex, which is the point in the sky toward which our solar system is moving as we orbit the Milky Way, is located in Hercules, not far from the very bright star Vega, which is in the neighboring constellation Lyra.

But the most interesting object is globular cluster M13, in spite of its watered down faintness.

A globular cluster is a spherical collection of stars that orbits a galaxy the same way we orbit the Sun. They are tightly bound by gravity, which gives them their spherical shape and accounts for the high stellar density toward their center. M13, about 25,100 light years distant, is thought to contain as many as a million stars. In its center, stars are about 500 times more concentrated than what we find in the neighborhood of our Sun. To the naked eye it appears as a faint smudge among the stars.

Because of its high density of stars, which in turn suggests a greater possibility of planets with some form of intelligent life, a message was beamed toward M13 in 1974 designed to communicate our existence to them. Sending the message was more a demonstration of the technical capabilities of the Arecibo radio telescope (in Puerto Rico) than any real attempt at communication. After all, by the time we receive a reply, more than 50,000 years will have passed.

To locate Hercules (and its distant globular cluster), simply look overhead after sunset; most (but not all) of the stars between the two brightest stars up there (Arcturus and Vega) are Hercules. If you can make out a faint smudge of light, that's M13; it'll be receiving our message in only 25,065 years.