Nepedia
Back to Discover
Advanced Reader
🚀

Ursa Minor

space Maturity 11-13 Next article →

Ursa Minor is a constellation located in the far northern sky. It is often called the Little Bear. In North America, many people call it the Little Dipper. This name comes from its seven brightest stars. These stars look like a small ladle or scoop.

UrsaMinorCC
UrsaMinorCC

This constellation is the 56th largest of the 88 modern constellations. It covers an area of 256 square degrees. Because it is in the far northern celestial hemisphere, it is only visible to observers in the northern hemisphere.

Ursa Major - Ursa Minor - Polaris
Ursa Major - Ursa Minor - Polaris

The most important star in this group is Polaris. Polaris is also known as the North Star. It is a yellow-white supergiant star. It is located about 432 light-years away from Earth. This star is a triple star system. The main supergiant star has two smaller yellow-white companions. One companion is 17 astronomical units away. The other is 2,400 astronomical units away. Polaris is also a Cepheid variable star. This means its brightness changes slightly. Its apparent magnitude ranges from 1.97 to 2.00.

Ursa Major - Ursa Minor - Polaris
Ursa Major - Ursa Minor - Polaris

Other stars in Ursa Minor have very unique properties. Beta Ursae Minoris is named Kochab. It is an orange giant star. This means it is an evolved star. It has used up the hydrogen in its core. Kochab is about 131 light-years away from us. It is 450 times more luminous than the Sun. It also has a diameter 42 times larger than the Sun. Scientists have detected a planet orbiting Kochab. This planet is about 6.1 times as massive as Jupiter.

NGC 6217 hs-2009-25-bc-full
NGC 6217 hs-2009-25-bc-full

Another star in the constellation is Gamma Ursae Minoris, or Pherkad. Kochab and Pherkad are called the "guardians of the pole star." These stars help people find the North Star. The constellation also contains very extreme objects. There is an isolated neutron star named Calvera. There is also a white dwarf named H1504+65. This is the second-hottest white dwarf ever discovered. Its surface temperature is 200,000 K. These stars show how much variety exists in space.

Humans have studied Ursa Minor for thousands of years. The Babylonians knew it as the "Wagon of Heaven." It was listed in the MUL.APIN catalogue around 1000 BC. The astronomer Ptolemy listed it in the 2nd century. The Greeks had many different names for it. One name was Cynosura, which means "dog's tail." Some myths say the stars are two bears. These bears saved Zeus from his father, Cronus.

Sidney Hall - Urania's Mirror - Draco and Ursa Minor
Sidney Hall - Urania's Mirror - Draco and Ursa Minor

Navigation has always relied on this constellation. In ancient times, the celestial pole was closer to Kochab. Since the medieval period, people have used Polaris to find north. Polaris stays within 1 degree of the north celestial pole. This makes it a reliable guide for mariners. In the Inuit tradition, the brightest stars are called Nuutuittut. This means "never moving." This name describes how the stars stay near the pole.

Book of the Fixed Stars Auv0043 ursa minor cropped
Book of the Fixed Stars Auv0043 ursa minor cropped

You can use Ursa Minor to practice stargazing. The four stars in the Little Dipper's bowl have different magnitudes. They range from second to fifth magnitude. This makes them great for testing your eyesight. You can find Polaris by looking at the Big Dipper. Find the two stars at the end of its bowl. These are called the Pointers. Follow a line from them for 30 degrees. This line will lead you straight to Polaris. This connection between constellations helps you map the entire sky.

562 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (5)
File:Sidney Hall - Urania's Mirror - Draco and Ursa Minor.jpg
Sidney Hall - Urania's Mirror - Draco and...
File:Book of the Fixed Stars Auv0043 ursa minor cropped.jpg
Book of the Fixed Stars Auv0043 ursa...
File:UrsaMinorCC.jpg
UrsaMinorCC.jpg
File:Ursa Major - Ursa Minor - Polaris.jpg
Ursa Major - Ursa Minor - Polaris.jpg
File:NGC 6217 hs-2009-25-bc-full.jpg
NGC 6217 hs-2009-25-bc-full.jpg
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.