Tonight, find the stars Kochab and Pherkad in the Little Dipper.
Can’t ever find the Little Dipper you say? Not surprising. It’s fainter and looks less like a dipper than the Big Dipper.
Just notice that – if you draw an imaginary line between the two outer stars in the bowl of the Big Dipper – and extend that line northward on the sky’s dome, you’ll come to Polaris, the North Star. Polaris is part of the Little Dipper. It marks the end of the Little Dipper’s handle. Kochab and Pherkad are the two outer stars in the bowl of the Little Dipper.
The Big Dipper appears high in the northeast sky at nightfall on spring evenings. It wheels above Polaris at late evening.
Polaris is special because Earth’s axis nearly points to its location in the sky. Polaris is less than a degree away from the true north celestial pole on the sky’s dome now. It’ll be closest to true north – less than half a degree away – in the year 2102. The change is due to a motion of Earth called “precession,” which causes Earth’s axis to trace out a circle among the stars every 26,000 years.
Polaris is less than a degree away from the true north celestial pole on the sky’s dome now. It’ll be closest to true north – less than half a degree away – in the year 2102.
Thousands of years ago, Polaris was an ordinary star in the northern sky, known to the Greeks by the name Phoenice.
Other ordinary stars in the northern sky now – Kochab and Pherkad, the two outermost stars in the bowl of the Little Dipper (see chart below) – have had the honor of being pole stars.
Kochab and Pherkad served as twin pole stars from about 1500 BC to about 500 BC.
They’re still sometimes called the Guardians of the Pole.
Kochab is located about 126 light-years away. Pherkad is more distant, at about 480 light-years by some estimates. Meanwhile, Polaris is a bit more than 400 light-years away.
Bottom line: Kochab and Perkad are in the Little Dipper asterism. You say you can find the Big Dipper but not the Little Dipper? This post will help.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.