In the 1960's, the first astronauts had to wear space suits and shoes with magnets to hold them down. Space suits were made of fifteen layers of material to keep the correct pressure inside. All those layers and heavy shoes made it hard to move. Imagine wearing ten-pound shoes, fifteen shirts, and fifteen pairs of pants at the same time.
Gravity tends to hold millions of stars together in groups called galaxies.
Our galaxy forms a spiral shape called the Milky Way. It is where we live. Two thirds of Earth's surface is covered with water. That is why it looks blue. Hundreds of years ago, people used to think that the Moon, the Sun, the planets, and all the stars revolved around Earth.