Why Orion Rules Only the Winter Sky
If you look south on a cold winter evening, you may spot three bright stars in a short, straight row. They make the belt of Orion, a famous group of stars. But go outside on a warm summer evening and look for Orion, and you will not find it. The stars have not gone anywhere. Earth has moved.
Earth travels around the sun once every year. The stars stay in place, but our view of them changes as we go. At night, we face away from the sun, so we see the part of the sky that is opposite to it. In winter, that part of the sky holds Orion. For people in the northern half of the world, it climbs into view in the evening and stays up for much of the night.
By summer, Earth is on the other side of the sun. Now Orion lies in the same direction as the sun. It rises and sets with the sun during the day, and the bright sunlight hides it from us completely. Other groups of stars take its place in the night sky, such as the Summer Triangle.
This is why each season has its own stars. If you watch the sky through the year, you can see Earth's journey around the sun, one new group of stars at a time.