We use a telescope to look at the stars and planets in the sky. The telescope is a long tube with two ends. If you look through one end, it allows you to look at objects that are far away at the other end. The special lens in the telescope can make the far away things stretch-out so that they are big enough for us to see. Thanks to telescopes, we have been able to discover so many planets and stars in space. But you should remember never to look directly at the sun as this can cause permanent damage to your eyes due to the brightness of the Sun.
Galileo was the first to look at the planets, leading to the discovery of satellites of Jupiter and craters on the moon.