The Big Dipper is one of the easiest patterns of stars to locate in the sky. It’s visible just about every clear night in the Northern Hemisphere, looking like a big dot-to-dot of a kitchen ladle. The Big Dipper with its neighbor, the Little Dipper, rotates around the north star Polaris as Earth spins.
If you can spot the Big Dipper, then we’ll help you find the Little Dipper and the North Star, Polaris.
Depending upon the season of the year, the Big Dipper can be found high in the northern sky or low in the northern sky. Just remember the old saying spring up and fall down. On spring and summer evenings, the Big Dipper shines highest in the sky. On autumn and winter evenings, the Big Dipper sweeps close to the horizon.
Given an unobstructed horizon, latitudes north of the 35th parallel (the approximate location of the Mediterranean Sea and Tennessee’s southern border) can expect to see the Big Dipper at any hour of the night for all days of the year. As for the Little Dipper, it is circumpolar – always above the horizon – as far south as the Tropic of Cancer (23.5 degrees north latitude).
The Big Dipper has two parts, a bowl and a handle. Notice the two outer stars in the bowl of the Big Dipper. They are called Dubhe and Merak, and an imaginary line drawn between them goes to Polaris, the North Star. That’s why Dubhe and Merak are known in skylore as The Pointers.
In turn, Polaris marks the end of the Little Dipper’s Handle. So why isn’t the Little Dipper as easy to pick out as the Big Dipper? The answer is that the stars between Polaris and the outer bowl stars – Kochab and Pherkad – are rather dim. You need a dark country sky to see all seven of the Little Dipper’s stars.
The Big Dipper is really an asterism, that is, a star pattern that is not a constellation. The Big Dipper is a clipped version of the constellation Ursa Major the Big Bear, with the Big Dipper stars outlining the Bear’s tail and hindquarters. In the star lore of the Mi’kmaw nation in northern Canada, the Big Dipper is also associated with a bear but with a twist. The Mi’kmaw see the Big Dipper bowl as Celestial Bear, and the three stars of the handle as hunters chasing the Bear.
The starry sky serves as a calendar and a story book, as is beautifully illustrated by the Mi’kmaw tale of Celestial Bear. In autumn, the hunters finally catch up with the Bear, and it’s said that the blood from the Bear colors the autumn landscape. In another version of the story, Celestial Bear hits its nose when coming down to Earth, with its bloody nose giving color to autumn leaves. When Celestial Bear is seen right on the northern horizon on late fall and early winter evenings, it’s a sure sign that the hibernation season is upon us.
The Little Dipper is also an asterism, these stars belonging to the constellation Ursa Minor the Little Bear. In ancient times, the Little Dipper formed the wings of the constellation Draco the Dragon. But when the seafaring Phoenicians met with the Greek astronomer Thales around 600 B.C., they showed him how to use the Little Dipper stars to navigate. Thereby, Thales clipped Draco’s wings, to create a constellation that gave Greek sailors a new way to steer by the stars.
In Thales’s day, the stars Kochab and Pherkad (rather than Polaris) marked the approximate direction of the north celestial pole, the point in the sky that is directly above the Earth’s North Pole.
To this day, Kochab and Pherkad are still known as the Guardians of the Pole.
Astronomers sometimes speak of the fixed stars, but they know that the stars are not truly fixed. They move in space. Thus the star patterns that we see today will slowly but surely drift apart over time.
But even 25,000 years from now, the Big Dipper pattern will look nearly the same as its does today. Astronomers have found that the stars of the Big Dipper (excepting the pointer star, Dubhe, and the handle star, Alkaid) belong to an association of stars known as the Ursa Major Moving Cluster. These stars, loosely bound by gravity, drift in the same direction in space.
In 100,000 years, this pattern of Big Dipper stars (minus Dubhe and Alkaid) will appear much as it does today! But there will be some differences, as illustrated in the drawing below:
Bottom line: You can find the Big Dipper and Little Dipper in northern skies any time of year. The North Star, Polaris, is located at the end of the Little Dipper’s handle.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.