One of the most common questions I hear under the night sky is: “How do I find the North Star?”
I’m always surprised by how many folks believe that the North Star (or Polaris, as astronomers know it) is the brightest star in the heavens.
At this time of year, I frequently hear people pointing toward the dazzling star Sirius, saying, “There’s the North Star.” The fact that it’s in the south apparently doesn’t bother them much!
If you have ever believed this astronomical myth or use a similarly bright star to find your way at night, you’re sure to become hopelessly lost.
No, the North Star is, as you might expect, in the north. And it’s not the brightest star in the sky, either. Far from it.
In fact, it’s the 48th brightest star, so unless you have pretty dark skies without much light pollution or moonlight, you’ll be surprised at how tough it is to see.
Though it’s quite faint, locating it at this time of year becomes a bit easier because the Big Dipper has returned to our evening sky, and as just about every scout in the world knows, the Dipper serves as a very clear pointer toward Polaris.
Later this week, when the brilliant full moon has left the early evening sky, go outdoors and face north. Low in the northeastern sky, you’ll find the seven equally bright stars of the Big Dipper, so named because this star grouping resembles a ladle with a bent handle.
In the United Kingdom, it’s known as the “Plough,” in Germany as the “Great Wagon” and elsewhere by many other creative names.
The Dipper, which is part of a larger constellation known as Ursa Major, the Great Bear, appears during late winter and early spring to be standing on its handle after dark.
Now, cast your gaze toward the northwest; there you’ll find the constellation of Cassiopeia, named for the ancient Ethiopian queen it’s supposed to represent.
Forget searching for a queen, though; you’ll have a much easier time spotting a sideways “M” shape outlined by five equally bright stars.
Midway between these two star groupings lies Polaris. This star is important because it stands directly above our planet’s North Pole.
This means that the Earth’s rotational axis aims in its direction at this time in history, so as the Earth rotates during the night, the northern stars all appear to revolve in a counterclockwise direction around Polaris.
Now, how do we use the stars of the Big Dipper to find Polaris? Pretty simple, actually. At the Dipper, connect the two bowl stars farthest from the handle and extend that line — from the bowl’s base to its top — about five times their separation.
There, you’ll find Polaris. And if you continue this line about the same distance past Polaris you’ll encounter the star Caph, which marks the bottom of the sideways “M.”
Because of their positions near Polaris, the Big Dipper and Cassiopeia always lie opposite each other, with Polaris midway between them.
So this summer, when you see the Dipper nearly overhead, Cassiopeia will appear quite low in the north, or even below the horizon.