Our solar system has eight planets. Mercury is the closest planet to the Sun, and Neptune is the farthest. Jupiter is the largest planet — it is much larger than Earth. Mars is called the “Red Planet” because its surface is covered with red dust. There is a very thin atmosphere on Mars, but there is no liquid water on its surface. Saturn is famous for its beautiful rings. Scientists believe there may be ice under the surface of some moons. The Earth is the only planet in our solar system that has life.

Space exploration started many years ago. In 1957, the Soviet Union launched Sputnik, the first satellite, into space. In 1961, Yuri Gagarin became the first person to travel in space. In 1969, Neil Armstrong walked on the Moon for the first time. He said his famous words when he stepped on the surface. In 2003, the Mars Exploration Mission began. Scientists sent rovers to Mars to discover evidence of water. In 2015, NASA’s New Horizons spacecraft reached Pluto and took the first close-up photos.