The Little Dipper is one of the oldest recognized star constellations in the Northern Hemisphere. It’s located about 30 degrees southeast of the Big Dipper, and it includes one of the most important stars in the night sky, the North Star, or Polaris.
For thousands of years, sailors have used the Little Dipper to navigate their routes at night. Until around the 19th century, the Little Dipper was known as Ursa Minor, or the “Little Bear,” as ancient astronomers tended to use bear-related names for heavenly bodies.
It wasn’t until around the middle of the 19th century that American astronomers adopted the Dipper moniker for both Ursa Major and Ursa Minor, deriving that name from an African source, which labeled it the “Drinking Gourd.” The Little Dipper is almost exactly centered around the North Pole, making it ideal for navigation in most places throughout the Northern Hemisphere.
Little Dipper Mythology
All ancient cultures told stories about the stars and heavenly bodies. Star gazing was a natural pastime in the days before electric lights made the stars invisible at night in big cities. Ancient cultures had thousands of years to look up at the stars, observe them slowly rotating each night and take note of their larger annual patterns.
Greeks, Phoenicians and Native Americans
Although the Greek myth of Ursa Minor is only a couple of thousand years old, just about every culture throughout history has observed the North Star in its nearly fixed place above the North Pole. The Inuit name for Polaris is “Nuutuittut,” which means "never moving.” Since the North Star is almost directly above the North Pole, however, it isn’t useful for navigation at the far-northern latitudes where Inuit people live.
By around 1000 B.C., the Babylonians knew Ursa Minor as the “Wagon of Heaven,” and ancient Phoenicians may have shared their navigational knowledge with Greeks on their trade routes. The “bear” naming convention is probably Greek, and the name “Little Bear” is almost certainly derived from the original “Big Bear,” which Homer cites as a navigation aid for the Greeks in the “Odyssey.”
What Is the Little Dipper?
The Little Dipper is a star constellation consisting of the following seven stars:
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Polaris, or Alpha Ursae Minoris
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Kochab, or Beta Ursae Minoris
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Yildun, or Delta Ursae Minoris
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Pherkad, or Gamma Ursae Minoris
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Zeta, or Ursae Minoris
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Eta, or Ursae Minoris
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Epsilon, or Ursae Minoris
In Western culture, it’s one of the original 48 Ptolemaic and 88 modern constellations. The brightest star in the constellation, Polaris, is the 48th brightest star in the sky with an apparent magnitude of 1.97 to 2.00. You can find it by locating the more easily recognizable Ursa Major, or “Big Dipper,” and then following its two lowermost stars 30 degrees southeast to the “ladle handle” of the Little Dipper.
Little Dipper Proximity
The two Big Dipper stars that point to Polaris are called, respectively, Alpha and Beta Ursae Majoris. They comprise the edge of the Big Dipper’s “bowl,” and many people call these stars the “Pointers” because of their relative proximity to Polaris and Canes Venatici. Located at the bottom of the Little Dipper’s “bowl,” Kochab, the second-brightest star in Ursa Minor, has an apparent magnitude of 2.08, making it visible at night even in most large cities.
Little Dipper Facts
In modern astronomy, the Little Dipper ranks 56th in size out of 88 star constellations, or asterisms. While it’s one of the smallest constellations in the night sky, it occupies 256 square degrees of the stellar sphere surrounding Earth. Its brightest star, Polaris, is 431 lightyears from Earth. It goes by many names, including Pole Star, Lodestar, Star of Arcady and Alruccabah.
Most of the other stars in Ursa Minor are closer to Earth than Polaris. Kochab, for example, is only 126 lightyears away, but because it’s a relatively dim red giant, it has a lower apparent magnitude. The most distant star in Ursa Minor is Pherkad at 480 lightyears from Earth and an apparent magnitude of 3.04. Polaris, Kochab and Pherkad are the only stars in Ursa Minor visible to the human eye from light-polluted locations.
Ursa Minor Appearance
The types of stars in Ursa Minor include orange giants, red giants and yellow-white supergiants. They range in apparent magnitude from 4.21 to 5.02, making them too faint to shine through the atmospheric haze of big city smog and electric lights. As far as deep-sky objects are concerned, the Little Dipper has relatively few. There are only around three or four known galaxies within the Ursa Minor constellation.
Most Important Stars in Ursa Minor
The three brightest stars, Polaris, Kochab and Pherkad, are the most useful for navigation and for locating nearby objects in the night sky. While Polaris looks like one star to the naked eye, it’s actually a cluster of three stars locked in orbit.
Ursa Minor Stars and Exoplanets
The main star, Polaris Aa, is a supergiant with 5.4 times the mass of the Sun, and no one is sure if it has any planets orbiting around it. Kochab, on the other hand, has at least one confirmed planet, a gas giant called Beta Ursae Minoris b. Likewise, there is at least one confirmed planet orbiting Pherkad, a gas giant called Pherkad Minor b.
The stars in Ursa Minor are important for another reason, as well. They form the backdrop of an annual celestial event called the Ursid Meteor Shower, which occurs from December 18 to December 25.
Where Is the Little Dipper Located?
While many sailing cultures have used the Pole Star for nighttime navigation since the invention of sailing, some cultures have been unable to do so. When the Inuit looked up at night, they saw three stars remaining stationary while the rest of the starfield rotated in a regular orbit.
The reason the North Star hardly moves with the Earth’s rotation is that it marks the northernmost tip of the Earth’s axis. Because Polaris falls almost exactly in line with the Earth’s axis, the Earth simply rotates around it without deviating from its apparent position.
Depending on which hemisphere you’re standing in, the Little Dipper could be upside-down or rightside-up. In either case, the right ascension and declination variables will be the same, so you can simply follow a star map to find the constellation.
