by Sarah Todd

Created on: August 12, 2008

For centuries the North Star has been a reliable and accurate navigational aid for travellers. For anyone lost in a strange and dark place in the wilderness the Northern Star is a very important navigational tool.

Polaris is the name of the current North Star, and it is 431 light years from Earth. It's also known as the Lodestar or Pole Star. While not the brightest star in the night sky, it is the brightest member of the constellation Ursa Minor, also known as the Little Bear.

The North Star can also be used to determine latitude. Because it always appears due north, the angle created with the horizon is the same as the latitude of the point from which it is being observed. The North Star is visible only in northern hemisphere skies, and cannot be used south of the equator.

It's not difficult to locate the North Star. The first step is to find the Big Dipper, easily identifiable due to its distinctive shape and its large size. Also known as the Great Bear, or Ursa Major, the Big Dipper does dip in different directions depending on the time of year because it rotates around the North Star. The changed dip does not make it difficult to find.

The Big Dipper stays above the horizon all night, which means it can be used to locate the North Star at any time. This is because it is a circumpolar constellation, so it rotates around Polaris due to the Earth's rotation. Polaris is just two thirds of a degree from the North Pole, so it appears constant and unmoving. The stars in the Big Dipper are also fairly bright, so this helps to locate and identify the constellation.

Once sited, look for the two stars on the edge of the dipper, and draw an imaginary line straight through those two stars towards the Little Dipper constellation. This line points very close to the Little Dipper's "handle". The brightest star in that handle is the North Star, and it indicates true North. When facing the North Star a traveller can easily identify the other points on the compass. To the right is the East, West is to the left and the South will be behind him.

The Big Dipper and Polaris were used by slaves travelling north to Canada as they fled the southern states prior to the outbreak of the United States' Civil War. They were able to locate Polaris using the pointer stars together with the words of a song titled "Follow the Drinking Gourd", which contained coded directions for the escape route used from Alabama and Mississippi.

Many myths have evolved around the North Star. The Native American people tell of a young man named Na-Gah, who wanted to impress his father. He decided to climb the highest mountain in the land. Although the ascent was difficult, he persevered and finally reached the summit. Unfortunately, there was no way down the mountain. When his father found him, he realised his son would never be able to return home. Not wanting him to suffer for achieving such a courageous feat he turned Na-Gah into the North Star, so he would always be seen and honoured by all living creatures.

Polaris hasn't always been the North Star, and in time another star will take its place. In the year 3000 BC Thuban, a star in the constellation Draco, was our planet's North Star. Alrai, which is 45 light-years from Earth, will move closer to the northern celestial pole than Polaris in around 3000 AD, with its closest approach scheduled for around 4000 AD. Polaris will be replaced by Iota Cephei 115 light-years from Earth - as the North Star some time around 5200 AD. By 14000 AD the first magnitude star called Vega, which is 26 light years from Earth, will assume the role of North Star.

Learn more about this author, Sarah Todd.
Click here to send this author comments or questions.