Using the stars to navigate at sea
In a time before satellite navigation systems and smartphones, sailors would rely on other instruments to navigate across deep sea waters and vast oceans. Captains would use compasses, charts and landmarks to work out their position – and in which direction they needed to be heading.
We may all enjoy the benefits that modern technologies offer us today but electrical systems can fail – and without a GPS on board, sailors have to be confident they’ll know how to get to their destination. Although the majority of our berth holders at Sutton Harbour Marina will know Plymouth Sound and South West waters extremely well, when sailing further afield and into unknown waters, it’s still a good idea to know something about traditional means of navigation.
Voyagers and explorers have used the stars to navigate for thousands of years, a technique that seems to have died out with the introduction of easier and more reliable methods. But navigating using constellations doesn’t have to be difficult, as long as you know what you’re looking for.
The North Star
The North Star is one of the most important stars in the sky for navigation. Also known as Polaris, the North Star sits directly above the North Pole and doesn’t move with the rotation of the Earth. To locate north, simply find the North Star.
Many people believe that the brightest star in the sky is the North Star but this isn’t necessarily true. Although the North Star is bright, there are some key constellations to look out for that will help you to identify the correct star.
How to find the North Star
If you find the Plough, also known as Ursa Major, you will be able to find the North Star. The Plough is a group of seven stars that are easy to identify as some say the constellation looks like a saucepan. The Plough rotates anti-clockwise around the North Star and the two pointer stars (which are at the ‘pan’ end of the saucepan) point towards the North Star.
The Cassiopeia constellation sits at the opposite side of the North Star than the Plough and is shaped like a ‘W’. The constellation was named after a fabled queen in Greek mythology and is the wife of Cepheus, the constellation beside Cassiopeia and next to the North Star. The most significant star in Cepheus is the Garnet Star as it is one of the biggest in the Milky Way.
How the North Star helps you to navigate
Once you have located the North Star, not only will you be able to head due north, you will be able to work out your latitude. In the northern hemisphere, your latitude will be the same angle as the North Star from the horizon. This can be measured using a sextant or, if you have no tools to hand, use your fists to measure the distance from the horizon to the star; each fist is approximately 10 degrees.
The constellation of Orion is one of the brightest and well-known constellations in the sky. It can be used to locate south, east and west. It’s best seen at night during winter and early spring and also just before dawn in the summer.
Orion’s belt is three stars in a row forming a straight line and is easily recognisable. Like the sun, Orion’s belt rises in the east and sets in the west, with the first star in the belt always rising and setting within one degree of due east and due west. The stars are level with the horizon as they rise and perpendicular as they set. Down from the middle of Orion’s belt is Orion’s sword, a short line of stars which point close to due south.
Luckily for us here in the UK, navigating in the northern hemisphere is considered much easier than navigating in the southern. And although we have many means of navigation, both modern and traditional, learning to navigate using the stars is not only interesting but is an added skill and could be especially useful if you’re ever sailing at night.