People have been wondering about what they see in the sky for a long time. Because of our curiosity about the sky, we tell stories and myths about what we see there. The desire to explain what we see around us in the simplest way using science has driven astronomers for centuries.
By carefully watching the sky, astronomers learn about how the universe works. By studying eclipses and the motions of the planets, astronomers eventually realized that gravity controls the way things move, and that gravity was responsible for the motion of the Sun, the Moon, and the stars in our sky as well. We now know that the Earth’s motion is responsible for seasons.
Telescopes allow us to “see” further away. With them, we can study stars and galaxies, as well as many of the more mysterious objects in our Universe.
source: windows to the universe