Blue Planet Project

Sky School for any month
 
I'll start with the star groupings most are already familiar with - the Big Dipper and Cassiopeia. They are big and bright, and they are visible from Canada every clear night of the year. Once you know them, they will help you find many other constellations. Think of them as beginning guideposts.

In January, Cassiopeia is high in the sky to the North just after dark, and the Big Dipper is quite low, near the horizon. In Spring, the Big Dipper is high overhead and Cassiopeia is low in the North.  Between them are the Little Dipper and the faint arc of stars that form Draco, the Dragon.

The end stars of the Big Dipper's bowl are called "the pointers"; they point to the pole star, Polaris. Polaris is very near to the point where the Earth's axis would meet the sky, so all the stars seem to rotate around Polaris as the Earth turns. The map is about right for 7:00 pm in mid-January; rotate it about 15 degrees counter-clockwise for every passing hour.  Similarly, rotate it about the same amount for each passing month.

There are 88 recognised constellations, many named for figures from ancient Greek mythology. The Big Dipper isn't actually a constellation, but an "asterism", a group of stars belonging to one or more constellations. It's part of Ursa Major - the Great Bear. The Bear is a large constellation, but most of its stars are faint, except for the Big Dipper. I show you the whole thing in another article.

Cassiopeia is in the Milky Way, the band of faint stars that trace our own galaxy in the sky. Grab some binoculars and a lawn chair, and have a look -- it's well worth your while.