Observer's Corner for March 2019
The Big Dipper
Celestial Navigation and Time Tool...Asterism
In the North sky, the very easy to spot Big Dipper swing around the pole star Polaris like a rider on a Ferris wheel. It goes full circle in the sky once a day – or once every 23 hours and 56 minutes. If you live in the Northern Hemisphere, simply look northward and chances are that you’ll see the Big Dipper in the nighttime sky.
The Big Dipper is really an asterism – a star pattern that is not a constellation. Part of the constellation Ursa Major (Big Bear), the Big Dipper stars outline the animal's tail and hindquarters. In the star lore of some Indian tribes of northern Canada, the Dipper is also associated with a bear but with a different twist. The Mi’kmaw see the star group's bowl as the Celestial Bear, with the three stars of the handle as hunters chasing the Bear.
Depending upon the season of the year, the Big Dipper can be found either high or low in the northern sky. On Spring and Summer evenings, the Dipper shines highest in the sky while on Autumn and Winter evenings, it moves closer to the horizon.
Given an unobstructed horizon, latitudes at 35 degrees North or higher, can expect to see the Big Dipper at any hour of the night for all days of the year.
Use the Angle Between the Ground and Polaris to get your Local Latitude on Earth
Horizon
Your Latitude on the Earth
Polaris
