Observations and Explorations of Venus - Summary

Summary

Observations may have been first recorded by Babylonian astronomers around 1600 BC and have continued into the present. The Mayans also kept records of the movements of Venus and attached special importance to the planet. In 1610, Galileo Galilei was the first person to observe Venus through a telescope, and discovered that it appears to undergo phases, supporting the heliocentric model of planetary motions. Important later observations centered around rare transits of Venus, in which the planet passes across the face of the Sun as seen from Earth. During one transit in 1761, Mikhail Lomonosov discovered that Venus has an atmosphere, and another transit in the 19th century allowed astronomers to calculate the distance from Earth to the Sun. In the early 1960s, astronomers studied Venus by making radar and microwave observations from Earth, which suggested Venus has a surface temperature of several hundred kelvins.

The exploration of Venus by space probes began shortly after the Space Age, starting with the Soviet probe Venera 1 in 1961. The first successful Venus fly-by probe was NASA's Mariner 2, which confirmed its high surface temperatures. In 1966, Venera 3 became the first spacecraft to reach the surface of another planet when it crash-landed on Venus. Its successor Venera 4 succeeded in returning data during its descent, reporting that the atmosphere of Venus was 95% carbon dioxide and the surface pressure around 100 times greater than on Earth. Venera 7 made the first successful soft landing in 1970. In 1975, Venera 9 and 10 were the first spacecraft to enter an orbit around Venus, each also dispatching a lander to the surface. They were followed by several other NASA and Soviet orbiter/lander missions during the late 1970s and 1980s, including Veneras 11 through 16, Pioneer Venus, and Vega. However, there have been fewer Venus missions since the collapse of the Soviet Union. Between 1990 and 1994, NASA's Magellan orbiter mapped 98% of the surface using radar. The European Space Agency's Venus Express arrived in orbit around the planet in 2006, and is currently studying its atmosphere and surface characteristics.