Constellations of autumn appearing

Thursday, September 9, 2010

The sun is setting earlier and rising later each morning as we draw closer to the Autumnal Equinox. Summer is fading and the constellations of summer have passed to the western side of the meridian.

The meridian is an imaginary line that runs from due south to due north overhead, it marks the middle of the sky dividing it into the eastern half and the western half.

The constellations of autumn are making their appearance in the west after sunset. About an hour after sunset the first of the fall crew, Pegasus, the Flying Horse, can be observed in the east.

Although it is called a square, right now it looks more like a baseball diamond tipped up on one corner. Technically, the constellation is upside down.

As seen on star charts the head extends off of the star on the right (south) side of the diamond and the forelegs extend off the star at the top of the triangle.

The square is the body and that is all we see of the horse, the body, the head and the legs.

Extending off to the left of the star on the north side of the triangle are the two lines of stars making up another autumn constellation, Andromeda, where we have looked for the Andromeda Galaxy in previous columns.

Later in the evening, about 9 p.m. MDT, Perseus can be observed over the northeastern horizon. Perseus is where we observed the grand show of the Perseid Meteor shower back in August.

Perseus looks sort of like a capital letter "A." It is at the end of the arms of Andromeda and directly under the "W" shape of Cassiopeia.

By midnight, another autumnal constellation makes an appearance over the northeastern horizon, Auriga, the Charioteer. Its oval shape with the very bright star Capella on the top side can be located just below Perseus.

Right now, while you are thinking about it, go mark Saturday, Sept. 18, on your calendar as the day you will want to come outside with me and join the observance of the "International Look at the Moon" day.

The moon will be a little less than a week away from being full and should be a good object for observing. Check back here next week for a time and place. You will be joining thousands of others all around the world on that day who are setting time aside to observe the moon. It will be fun; make it a point to come join us.

SKY WATCH:

New moon tonight. In the western sky just after sunset, if you hurry, you might be able for the next few days to catch a glimpse of Venus, Mars, and Spica before they slip below the horizon. Venus is the brightest object visible in the west, Mars is a very small dot just up and to the right and the star Spica is just above the horizon to the lower right of the planetary pair making a nice triangle. On Friday, Sept. 10, a very slender crescent moon will be below Spica and Venus. On the next day it will be to the left of Venus. On the 13th it will be very close to Antares, the heart of the Scorpius, the Scorpion.

NEXT WEEK:

More astronomical blathering.

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