The North Star, Little Dipper and Ursa Minor

Last time, we talked a bit about the Big Dipper asterism and its parent constellation, Ursa Major, the Great Bear.  We are going to use the Big Dipper now to locate the most important star in our night sky, our north star, Polaris.

Here is what you do:

Stellarium.org

First, find the Big Dipper.  At 9 PM tonight, it is in the NNW sky (just to the left of being north).  Three stars make up its handle and four stars make its scoop.  The last two stars in the scoop are the ones we are looking for; individually, they are named Dubhe and Merak (Dubhe is on top) but together, they are called the pointer stars.  If you follow them up, they will point you right to Polaris, the North Star.

No matter what time of day or night, no matter what time of year, no matter if Brad and Angelina adopt another kid, those two stars will always point to Polaris.

Stellarium.org

The distance between the pointer stars and the North Star is about five times the distance between Dubhe and Merak themselves.

Many of my students (and many of their teachers) would often come up to me and inform me that the North Star is the brightest star in the sky.  Let me dispel that notion right here and now.  Polaris is nowhere near the brightest star in the sky; if you include the Sun, Polaris comes in at number 46 on the list of brightest stars.  It's claim to fame is that it doesn't move and it won't move for another 12,000 years or so.

The reason why it doesn't move is because Polaris is just above directly above the North Pole.  The Earth spins like a basketball on Curly Neal's finger (still the finest Harlem Globetrotter ever, in my opinion).  Now, Imagine yourself on top of that basketball, at the North Pole; are you spinning?

Yes, you are.  You are spinning in place and the whole world is spinning below you, but since you can't feel your own motion, it looks like the North Star, which is right above your head, is spinning in place.

Stellarium.org

Polaris is in the asterism known as the Little Dipper.  It is one of three stars that make up the Little Dipper's handle; to the left of the handle are four stars that make a rectangle, this is the Little Dipper's scoop.  Tonight, the scoop looks completely upside-down.

Now, to make the Little Dipper into the Little Bear, just begin with the North Star again.  The handle of the Little Dipper is Ursa Minor's tail. (Your tail would be abnormally long too if you were swinging around the center of the sky!) The scoop makes up the Little Bear's legs and body and to find the neck and head, just locate the two dimmer stars down and to the right of the lowest star in the Little Dipper's scoop.

Weird bear…

That's it for this post.  I am trying to keep each post short so that you won't have too much to look for in a single night, so if you want to know more about something I mentioned, please let me know and I'll go more in depth; and if you have any questions (nice ones) please feel free to ask them.  If I can answer them, I will and if I can't…well…I'll ignore it altogether. :-)

Good Luck and have fun looking up tonight!