As we know, stars do not move. Stars are like our sun. They are stationary and do not move, but planets and moons do move. They orbit stars. Anyhow, why it looks like that stars move? As you watch the sky in early night, it looks different than later at night. Stars change their position as the night goes on. They start rising in early evening, reach the highest position after midnight and finally go below the horizon in early morning. Only the circumpolar stars do not go below horizon, but also their position in our night sky changes. As an example, take a look at my previous post: Planet Saturn in Early February Observed from Northern Hemisphere.

The obvious reason for this phenomenon is that our planet move. The Earth circulates, and that’s why we see the sun and other stars changing their location in the sky. Because of this we have days and night. In addition to circulation, our planet is on move. We orbit the Sun and because of this we have winters and summers. Based on our continuous move we see the stars changing their location in our night sky. How could you see this happening? Here’s the tip for noticing how the stars move in the night sky.

We can easily see how the stars change their position in night sky. You need to observe the sky at least during two nights in order to notice the move. Find yourself an observation location in which you have either structures, trees or similar items that do not move. Find a star that is positioned high enough and is bright enough to observe. Examples of such stars in northern hemisphere are Capella, Betelgeuze, Deneb, Procyon and Regulus. Find a place from where observing the star and the structure are close to each other. Wait until you see the star going behind the structure, tree or similar object. Write down the time when this happened. Mark your position well because you need to come back at least once more.

Come back to the same position next night or later. If you observe the same star from exactly same the location, you should see the star going behind the structure about four minutes earlier. If you missed one night, this phenomenon should happen eight minutes earlier. The star goes behind the structure every night four minutes earlier, which means the sky “turns to right” a little bit every night.

See the images on left side. In the first image Deneb goes behind a tree in February 9th. 2008 at 6:19:16 pm. During the next night this same happens at 6:15: 30 pm., which is about four minutes earlier. This is an easy method to notice how stars change their position in our night sky, even though they do not move from their location in the Universe in relation to other stars and planets.