This image shows the constellation Ursa Major, the Big Dipper. The seven brightest stars (top left) are Ursa Major. Credit: Tony Hallas
Although it is visible year-round from mid- and high-northern latitudes, now is a great time of year for newcomers to stargazing to look for and find the famous pattern of stars known as the Big Dipper or the Plow.
Many people grow up believing that Ursa Major is a constellation, but it is not. It’s an asterism: a small, eye-catching pattern connecting the dots, made up of stars found within a single constellation or in nearby constellations. In the case of the Big Dipper, it is part of the constellation Ursa Major.
Although the Big Dipper is visible year-round from many places, its orientation in the sky changes throughout the year as the Earth revolves around the Sun, and also during individual nights as the Earth spins on its axis. This means that sometimes it looks like a big starry question mark in the sky, and other times it looks like an upside-down fish hook.
As darkness descends on these increasingly cold late autumn evenings, the Big Dipper actually looks like a ladle, or ladle, resting on the northern horizon. Its stars are bright enough to be visible as soon as the first stars begin to appear, making it perfect for those who have never seen it before to look for it.
However, the Big Dipper is not just an attractive star pattern to observe on a clear night. It can be used to locate many fascinating stars, constellations and objects of interest positioned around it in the night sky. But before we set off on a tour of the stars from Ursa Major, let’s take a look at the history behind Ursa Major and meet the seven stars we combine to draw it in our minds.
Tradition of the Ursa Major sky
Since the Big Dipper is visible from many countries, it should come as no surprise that there are many stories about it. For example, there are several fascinating Native American stories about the Chariot. To the Blackfeet people, the Big Dipper was a woman who was transformed into a bear and chased her brothers into the sky, where they all became the stars of the Big Dipper.
To the Micmac and Iroquois tribes, the Big Dipper is a bear chased across the skies by seven hunters. As autumn approaches, three hunters tire and fall below the horizon, leaving the remaining four to chase the bear. When he is finally killed, his blood colors the leaves red in the fall, and the bear’s skeleton remains in the sky through the winter. In the spring a new bear emerges, starting the hunt again.
In China, the Big Dipper is associated with many different deities and myths. One, Doumu, is known as the Mother of the Big Dipper. She is believed to have control over the stars and is often depicted in cards alongside the Big Dipper.
Stargazers in many Western countries have always viewed Ursa Major as part of the Big Dipper, the Big Dipper. The curved handle of the ladle represents the bear’s tail, which is rather strange because real bears don’t actually have long tails. Greek myths, however, explain this by suggesting that the bear was hurled into the sky by its tail, which lengthened as Zeus twirled it above his head before releasing it.
And in the UK and Ireland, the Big Dipper is not associated with a bear at all. It is instead known as a Plow, due to its resemblance to a traditional agricultural plow (or plow, in American English), pulled across fields by a horse.
The stars of the Big Dipper
With an apparent magnitude of 1.79, Dubhe (Alpha [α] Ursae Majoris) is the second brightest star in Ursa Major and the 33rd brightest star in the night sky. It is a spectroscopic binary and is located approximately 123 light-years from Earth. It is one of the best-known stars in the sky because, together with Merak (Beta [β] UMa), is one of the “pointer stars” that skywatchers use to locate Polaris, the North Star.
Shining at magnitude 2.37, Merak, 79.7 light-years away, is the fifth brightest star in the Dipper and the second brightest in the Pointers.
Megrez (Delta [δ] UMa) is the faintest of the seven Dipper stars, with an apparent magnitude of 3.3. A star of spectral class A3, it has a surface temperature of about 9,500 K, which gives it a white or blue-white color. It is located about 80 light years from Earth.
Phecda (Gamma [γ] UMa) is one of the stars that form the bowl of the Dipper. Its magnitude of 2.44 makes it the sixth brightest star in Ursa Major. It is located about 83 light years from Earth. Phecda rotates rapidly, at about 110 miles (178 kilometers) per second, which causes it to take on an oblate shape.
Alioth (Epsilon [ε] UMa) is the star on the handle of the Chariot closest to its bowl. It is the brightest star in the constellation. Its apparent magnitude of 1.77 makes it the thirty-first brightest star in the night sky.
Mizar (Zeta [ζ] UMa) is located in the center of the curved handle of the Ladle. It has an apparent magnitude of 2.04, making it one of the brightest stars in the constellation. Mizar is a famous double star visible to the naked eye, perhaps one of the most famous in the sky. With its twin Alcor (80 UMa), it is often considered evidence of good eyesight. In fact, Mizar itself is a quadruple star system consisting of two pairs of binary stars.
Alcaide (Aeta [η] UMa) marks the end of the Ladle’s handle. With an apparent magnitude of 1.86 it is the third brightest star in Ursa Major. It is located about 100 light years from us. Like Phecda, Alkaid is a fast spinner, spinning with an equatorial bulge speed of about 93 miles (150 km) per second.
Jumping among the stars from the Big Dipper
Amateur astronomy may seem like a daunting hobby at first, but every astronomer you see looking into the eyepiece of a high-tech, high-powered, bank-breaking telescope started out as a beginner who knew nothing. The way people begin to learn about the night sky is not by using complicated charts or maps, but by jumping among the stars in the sky, drawing imaginary lines between pairs or groups of stars and extending them to point the way to other objects.
Here are six items you can find by star hopping from Ursa Major. You won’t be able to see them all in one night because, depending on the time of night and your location, some will sometimes be below the horizon. But it’s worth the wait.
- Drawing a line between Dubhe and Merak, the aptly nicknamed Pointers, and extending it away from the bowl opening will take you to Polarthe famous Polar Star. Polaris is the brightest star in Ursa Minor, the Little Bear, which contains the Ursa Minor asterism.
- There is a saying in astronomy: “Follow the arc to Arcturus and speed up (or speed up) to Spica.” The bow in question is the curved handle of the Big Dipper. If you extend this curved line, you will come to your senses Arthurthe brightest star of Bootes the shepherd. Arcturus is the brightest star in the Northern Celestial Hemisphere (note: this is not the same as the Northern Hemisphere) and the fourth brightest in the entire sky. So if you cast your gaze in a straight line from Arcturus in the direction you were last curving, it will take you to Spicathe brightest star of Virgo, the Maiden.
- If you make a hole in the Ladle’s bowl and let all the water out, you will come to your senses Leo the lion. Initially you will see it as a question mark in reverse. This is an asterism known as the Sickle, the sharp-bladed cutting tool used by farmers harvesting crops. The Scythe is the front part of Leo and its lower star is Regulus, the brightest of Leo. To find the rest, look to the east for a triangle of stars whose brightest star is Denebola, a name that means “the lion’s tail.”
- Draw a line between Megrez in one corner of the Dipper’s bowl and Merak in the opposite corner, and stretch it away from the Dipper and you’ll be taken to a pair of nearby stars. These are Castor and Polluxthe brightest stars in the constellation Gemini.
- Returning to Megrez, draw a line between it and Dubhe and extend it until you get to a bright gold star. This is it Chapelthe brightest star in Auriga the Charioteer and the sixth brightest star in the sky.
- After you find Capella, extend that line from Megrez and Dubhe even further, almost as far, and you’ll come to two of the most famous star clusters in the sky, both in the constellation Taurus. The more obvious and smaller of the two is the Pleiadesaka the Seven Sisters or M45, which looks like a knot of blue-silver stars evident to the naked eye. Below the Pleiades is a larger, fainter cluster, a lateral V of stars called Hyades. The bright, reddish star at the end of the V is Aldebaran, the brightest sun in Taurus.
As you can see, there is much more to the Big Dipper than meets the eye. It’s not just a comforting and familiar star pattern, it’s a treasure trove of fascinating cultural stories and a marker for some of the most famous objects in the night sky.
