What is Polaris?
Q: What is Polaris?
A: Polaris (Alpha Ursae Minoris) is the Pole Star or North Star. It is the brightest star in the constellation Ursa Minor and almost straight above Earth's North Pole.
Q: How has Polaris been used historically?
A: For centuries, sailors in the northern hemisphere used Polaris to help them figure out where they were on the ocean and what way they were moving.
Q: Is Polaris part of a multiple star system?
A: Yes, it is part of a triple star system with a very close dwarf binary and a larger star, Polaris B, which orbits 2,400 AU away.
Q: When did Polaris become the North Star?
A: In 3000 BC, a faint star called Thuban in the constellation of Draco was the North Star. However, Polaris did not become the North Star until about AD 500.
Q: How long will it stay as closest to being straight above Earth's north pole?
A: It will get closer to straight above Earth's north pole until sometime in 2102 then move away again. It will be closest to being straight above Earth's north pole until about AD 3000.
Q: What type of star is Polaris A?
A: The main star, Polaris A, is a giant with 4.5 times the mass of the Sun and a diameter of 45 million kilometers. It is also classified as a classic Cepheid variable - one of the closest to us in our Milky Way galaxy.
Q: Is there an equivalent South Pole Star?
A: No, there isn't an equivalent South Pole Star that plays a similar role to that of Polarstar for those located in southern hemisphere regions on Earth
