Constellations

The kids wanted to see the fireworks, but Disneyland was an hour from home. It being summer, the sky didn’t darken until 9pm. They would sleep on the way home. I had to drive. The cars in front of me followed the flashlight pointing employees sending exit traffic in one direction. By the time all vehicles spilled out of the gates, I’d lost my bearings. Nothing looked familiar, and I couldn’t see the street names in the dark. Was I going in the right direction? I was too tired to keep driving until some main road could re-orient me. The astronomer in me cropped up. I pulled the car over just long enough to look up. With vehicles coming up behind me, I didn’t have to luxury to hunt for the dim North Star, the way I wanted to go. I looked for a familiar constellation instead. There in front of me hung Scorpio, and knew I’d have to do an about face to get home. Scorpio is south.

Constellations are groups of bright stars that form recognizable shapes in the sky. Sometimes referred to as asterisms, they were first catalogued by Ptolemy. Twelve of them familiar to our western culture are called the signs of the Zodiac. Taurus, Gemini, and Aries the Ram are not just in the daily news columns, they are in the sky. http://en.wikipedia.org/wiki/Asterism_%28astronomy%29 

The names of constellations, or star groups, are in Latin, while their individual stars have Arabic designations. Since, constellations make it easy to find specific stars, they work like a map of the sky which seafarers and farmers once depended on. The big dipper points to the north star, Polaris. Monthly shifts of constellations across the sky allowed farmers to know when to plant and when to harvest. http://www2.potsdam.edu/islamma/phys335constellations.htm

Maps pinpoint locations by latitude and longitude. This earth bound grid can be superimposed on the sky. On astronomical maps latitude is called declination, and longitude is right ascension.  Longitude, or right ascension, wraps around the earth like the time zones. They are measured in hours and minutes. Latitude, or declination, is given in degrees. If you want to find anything in the sky, you'll need to know hours, minutes, and degrees. http://csep10.phys.utk.edu/astr161/lect/time/coordinates.html

There are other constellations than the twelve of the Zodiac which lie along the ecliptic. Constellations near the equator are visible in both the northern and the southern hemisphere.  Aquilla, Corvus, and Canis Major can be seen along with others that lie within -30 degrees of the equator. Corona Australis at -40 and Carina at -60 are out of sight for most of North America.  http://www.dibonsmith.com/downunder.htm

 

In other cultures, like that of Native Americans, the shapes and names of constellations differ. The star patterns of the Greeks and Romans reflected their beliefs in their gods. The constellations of the native peoples, because they were so close to nature, form animal shapes. Even for these simple hunter gatherers, the constellations offered knowledge of seasonal changes and direction.  http://www.eaaa.net/strstory.htm

So get out those star maps and learn the names of the different constellations and find your way around them. Any continuing astronomical observations depend on it. http://stardate.org/nightsky/constellations