______ make it possible for astronauts to reach the moon.

The astronauts could not have reached the moon without the invention of rockets. We live in the age of rockets, but do you know that rockets are not a modern invention? For centuries, rockets were used to entertain people. The Chinese used rockets for fireworks. In the 13th century, rockets were first used in war. The Mongols used rockets to attack a Chinese city in 1232. These early rockets could not travel very far. However, in 1885 a Russian scientist discovered a better fuel for rockets. This liquid fuel gave rockets much more power. Then in 1919 a new age of rockets began. In that year an American scientist, Robert Goddard, said that it was possible to send a rocket to the moon! Goddard launched his first liquid-fuelled rocket in 1923. It flew 184 feet. Almost 12 years later, he sent a rocket 7,500 feet into the air in 1935. Russian rockets sent the first satellite into orbit in 1957. Just 12 years later the first man walked on the moon--thanks to rockets! Where will rockets take us next?