Wednesday, September 19, 2007

Our Moon & Four More

Time to resume Vagabonding, and to start things off, I've decided to do something of a little comparison. On Friday night, the 21st of September, the Moon will be slightly past first quarter and sitting high enough in the sky to make viewing good. Normally, for most astronomers, the Moon is a nuisance; the amount of light it reflects (notice; I said reflects and not emits) is considerable, and only the brightest objects can be seen with relative ease. The Moon, though, is quite worthy of observation, and I, for one, always try to observe it whenever possible, regardless of its phase.

Most of the detail we will see in this session will be along the terminator, where the shadows are still long (I've written about this in my "First Coast Sky @ Night" column). Those shadows add the necessary contrast for bringing out detail normally hidden from view. As you move away from the terminator and towards the limb (the edge of the sphere itself), you'll notice that the shadows diminish in length and detail is slowly erased due to an ever increasing angle of sunlight. Still, there is much that can be seen.

But Luna, our Moon, is only one of five we should be able to see that night. To find the others, we need to locate the planet Jupiter.

Jupiter is currently residing in the constellation Scorpius in the southern sky and is prominent just after sunset. You'll have no trouble at all locating the planet, as it will be by far the brightest object in the southern sky. It is far brighter than the red star Antares, which lies nearby. Once you've located Jupiter, a look through even a small telescope will reveal four small star-like objects sitting very close to the disk, the Galilean Satellites. The instruments I'll be using on Friday night will only allow us to view these four, though it should be remembered that Jupiter has an enormous retinue of moons, over seventy at last count. These four, its largest satellites, are planets in their own right, with Ganymede even larger than the planet Mercury.

The Vagabond Astronomer will be set up in the west parking lot at Ed Austin Regional Park in East Arlington after 8:00pm. To locate the site, I've included a map to help out. Hope to see you there!

ADDENDUM - 21 Sept.

A tropical depression formed in the Gulf of Mexico from a series of storms that crossed the state of Florida today. The weather deteriorated and ended up clouding up the night, so the little event was called off. Sigh. Oh well, there is next week...