Question

(i) If you observe the position of a star at a fixed time everyday, how many degrees higher will it appear after a month of 30 days?
(ii) Describe an activity to show that a star moves a certain angle in the sky relative to its position the previous day.

Answer 1

1)The stars we have seen the night before start their journeys around 1 degree further west each night before making their way across the sky and eventually disappearing off the western horizon. This can be explained by simple mathematics, as the Earth takes 365.256 days to complete a 360 degree orbit around the Sun, therefore after one day a star has changed its apparent position by 360 ÷ 365.25 = 0.99 degrees, or roughly 1 degree.

Taking this calculation a step further, we can that any individual star that has just appeared on the eastern horizon will have traveled 30 degrees higher westward after a 30 day period.