On Oct. 4, 1957, the Soviet Union launched Sputnik 1, the satellite that started the Space Race. [‘On This Day in Space’ Video Series on Space.com](https://www.space.com/39251-on-this-day-in-space.html)
Sputnik 1 was the first human-made object to orbit the Earth, and it set off a wave of fear and anxiety across the U.S. now known as the "Sputnik crisis." Sputnik was a metal sphere roughly 2 feet (58 cm) in diameter with four long radio antennas. These antennas transmitted little beeping pulses down to Earth that even amateur radio operators could hear. The satellite spent 21 days in orbit before it burned up in Earth's atmosphere.
