On this day in 1957, humans sent their first satellite into space.
Sputnik 1, named after the Russian word for “satellite,” was launched by the Soviet Union. It weighed 184 pounds and traveled at 18,000 miles per hour, circling Earth once every hour and 36 minutes and transmitting radio signals to the people on the ground. It fell out of its orbit three months later, and burned up in the atmosphere.
The United States, irked at having been beaten by the Russians in such an historic feat, caught up not long after. Explorer, the first American satellite, launched on January 31, 1958 and remained in orbit until 1970.
Today, there are about 1,350 operating satellites orbiting earth, according to the latest numbers from the Union of Concerned Scientists, a private organization that maintains a database of satellites. (Check out this cool interactive from Quartz on where exactly they all are.) The machines are used in communication, navigation, military operations and spying, weather forecasting, and more. The smallest is the size of a microchip, the biggest is the International Space Station.
About 2,600 other satellites have stopped working over the years, but continue to quietly circle the planet. The Russians, however, are no longer leading the way: Russia operates 131 satellites, while the U.S. has 549.
The satellites are among the 500,000 pieces of orbital debris, or “space junk,” currently whirling around the Earth. If you could see all that in space, it would look like this: