Why do different stars appear with seasons? (Beginner)

What causes different stars to appear in the sky at different times of the year?

There are two major motions affecting the Earth: its rotation around its axis, and its rotation around the Sun (which we call 'revolution'). While the rotation of the Earth on its axis causes the nightly movement of the stars across the sky, the revolution is responsible for the fact that we can see different parts of the sky at different parts of the year.

constellation season

Take a look at the image above. On a given day (meaning on a given position on the orbit), you will only be able to see the stars that are in the opposite direction to the Sun. All the stars that are 'behind' the Sun won't be visible during that day, because they are above the horizon during the day (and we can see stars only during night)! Now if you wait 6 months, the Earth will be at the opposite on its orbit, and you will now be able to see those stars that you couldn't see 6 months earlier because they were blocked by the Sun. This is why over the course of one year, we end up being able to see all the stars that are possible to observe from our latitude on Earth.

This page was last updated June 28, 2015.

About the Author

Jagadheep D. Pandian

Jagadheep D. Pandian

Jagadheep built a new receiver for the Arecibo radio telescope that works between 6 and 8 GHz. He studies 6.7 GHz methanol masers in our Galaxy. These masers occur at sites where massive stars are being born. He got his Ph.D from Cornell in January 2007 and was a postdoctoral fellow at the Max Planck Insitute for Radio Astronomy in Germany. After that, he worked at the Institute for Astronomy at the University of Hawaii as the Submillimeter Postdoctoral Fellow. Jagadheep is currently at the Indian Institute of Space Scence and Technology.

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