1 There are a lot of fast things in the world. Cheetahs and peregrine falcons are fast animals, and cars and airplanes can reach extremely high speeds. Then there are rockets and spaceships. They travel faster than any other objects humans have made, but animals and objects aren’t the only things that move fast. Sound and light also travel, and they do it pretty quickly.
2 Cheetahs are the world’s fastest land animals. They can sprint faster than 70 miles per hour. They can’t keep up that speed for long, but they don’t have to. Slower animals that are caught by cheetah ambush have no chance to escape. Peregrine falcons also use their speed to catch prey. They can reach about 200 miles per hour in an attack dive! There are other speedsters in the animal kingdom, but those are two of the fastest.
3 People also create machines that travel fast. Race cars can reach hundreds of miles per hour. The fastest jet planes can fly faster than 2,000 miles per hour, but rockets and spacecraft have to travel much faster than that. Anything launched into space has to maintain an orbital velocity of about 18,000 miles per hour, or it will crash back to Earth. The International Space Station and all of its astronauts are zooming around the Earth that fast! Spaceships that leave the Earth’s orbit must reach escape velocity, which is even faster, at about 25,000 miles per hour.
4 Measuring the speed of sound or the speed of light is harder than figuring out how fast a cheetah runs, but it is possible. Scientists have discovered that sound travels at about 750 miles per hour. That’s pretty fast for something that you can’t even see, but the speed of light is really impressive. Light travels at about 671 million miles per hour. Even at that speed, some areas in space are so far away that it takes light billions of years to reach us from those places.
5 There are some pretty fast things on Earth. Some are found in nature, and some are manmade. Some use legs, some have wings, and others have rocket engines. Even things that we don’t think of as “things” have speed. Sound is one great example, but it certainly is not the fastest example. Travelling 186,000 miles every second, it’s unlikely that light will lose a race to anything.
