What was the first satellite to orbit the Earth?

The first satellite to orbit the Earth was Sputnik. Launched by the Soviet Union on October 4, 1957, Sputnik marked a significant milestone in space exploration and the beginning of the space age. It was a simple spherical satellite, which transmitted radio signals back to Earth that could be received by amateur radio operators, demonstrating the potential for artificial satellites in scientific research and communication.

The significance of Sputnik lies not only in its status as the first artificial satellite but also in its broader implications for technology, politics, and international relations during the Cold War. The launch of Sputnik initiated the space race between the United States and the Soviet Union, leading to advancements in space technology and exploration.

The other options represent notable spacecraft but do not hold the distinction of being the first satellite. Soyuz is a series of spacecraft used for human spaceflight, Apollo 11 was the mission that first landed humans on the Moon, and Vostok 1 was the first crewed spacecraft to carry a human, Yuri Gagarin, into orbit around the Earth. While all these missions were significant, Sputnik is recognized as the pioneering satellite that orbited our planet.