Page 150 - Grasp English C1+ (Student Book)

|
Science Polaris, the North Star

Although Polaris isn’t the brightest star, it’s probably the most famous and one which perhaps most
people are able to identify in the night sky. This is due to the fact that it sits almost directly in line with
the Earth’s axis, meaning that as the world spins, Polaris will always be found due north. Were you to be
standing at the North Pole, the North Star would be directly overhead.
For sailors in the northern hemisphere, Polaris acted as a guide to travel by, as they could use it to judge
not only their direction, but also their latitude. The further north you travel, the higher Polaris can be seen
in the sky; when you’re at the Equator, you would see the North Star just touching the horizon. Sailors
would use a navigational device called a sextant to measure the distance between the North Star and
the horizon to plot their courses.
As Polaris is bright enough to be seen even with a full moon, it is one of the constants in the night sky
th
th
and has also had a vital role in the lives of many on land. During the 18 and 19 centuries, those in the
US who had been sold into slavery were able to use the North Star during their escape. The further north
they travelled, the closer they got to freedom.
Astronomers have discovered though that Polaris hasn’t always been the North Star, nor will it continue
to be in the future. Though in 12,000 years’ time when Vega becomes our new North Star, we won’t be
around to follow it.

148