If you follow a line through the "pointer stars" (the two stars in the bowl of the Big Dipper farthest from the handle) away fro
m the open end of the dipper, the first moderately bright star you come to is:______. A) Polaris, the North star.
B) Spica, in Virgo.
C) Arcturus, in Bootes.
D) Vega, in Lyra.
Polaris, also known as the Pole star or north star, lies almost along the axis of Earth. Because of this Polaris seems to be fixed at one point in the sky while all other celestial objects change their positions in the sky due to rotation of Earth.
Since, it is fixed at one point in the sky in the North direction, explorers used to take help of Polaris to find direction in the night time. Since Polaris is not the brightest star in the night sky (it is 48th brightest star) our ancestors took help of constellations to find it. One of the method was to use Big Dipper of "Ursa Major" constellation. The pointer stars (Merak and Dubhe) of big dipper point towards the Polaris. One can easily spot it in the sky as well.
<span>After landing on an unfamiliar planet, a space explorer constructs a simple pendulum of length 49.0 cm. The explorer finds that the pendulum completes 110 full swing cycles in a time of 144 s.