My Astronomy Class - Tracking the Great Bear

[Ad Astra]

Hello Folks,

Another new exercise for you this weekend, I hope the weather is good and you can have a go. This activity is designed to familarize you with the northern (circumpolar) sky, its constellations and its motion as it rotates around the pole.

Many beginning observers have difficulty with the idea of the stars and planets moving across the sky, even as the sun and moon do. All this diurnal motion is attributed to the Earth's rotation, of course - it is one thing to understand this intellecutally - quite another to see it in action!

The activity begins with a quick sketch of the circumpolar constellations: Ursa major, Ursa minor, Cepheus, Cassiopeia, Camelopardalis, and Draco. How much of these you can see will depend upon your sky conditions, and latitude. Here is southern California, we lose Draco almost completely this time of year - those of you who are more northerly have the advantage of us there!

Once you've got the regular constellations drawn, come back in 60-90 minutes and re-sketch just Ursa major again (on the same drawing!) You will note that it has risen farther off the horizon and that all the 'handle' is now visible. Add a third view after another 60-90 minute interval.

If you draw a line from Polaris to the pointer stars of the dipper for each of your three sketches of Ursa major, you should see that, like the hours on a clock face, the change in angle is consistent over time. Use your new data to project the position of the dipper three hours after your last observation and add that to your sketch as well.

You can use Stellarium (or the real sky!) to check your prediction later!

Cheers!

Dan

Obs #2 - Tracking the Great Bear.doc