Oct. 4th, 1957: Sputnik launches

Today in the history of astronomy, the first artificial satellite kicks off the Space Race. | Published: October 4, 2026 The beachball-sized Sputnik is shown in orbit around Earth, on this celebratory Soviet stamp. Credit: Public domain via Wikimedia Commons On Oct. 4th, 1957, at 10:29 PM Moscow time, the Soviet Union successfully launched Sputnik 1 into space on a repurposed R-7 rocket. The world’s first artificial satellite, Sputnik was about 22 inches (58 centimeters) in diameter and weighed 184 pounds (84 kilograms). Although there were no scientific instruments aboard, the transmitter it carried sent a beeping signal that radio operators worldwide could track. A shaken U.S. found itself suddenly lagging in the Space Race, not launching the first American satellite, Explorer 1, until January of the following year. The competition between the two superpowers spurred the creation of NASA and the race to land on the Moon. The Soviet technological dominance had alarming implications for the Cold War as well, suggesting the capability to launch ballistic missiles at the U.S. from the Soviet Union. Elisa Neckar is senior production editor of Astronomy magazine, and the editor of the Today in the History of Astronomy feature on Astronomy.com.