The Soviet Union launches Venera 1 towards Venus.

Venera 1, also known as Venera-1VA No.2 and occasionally in the West as Sputnik 8, was the first spacecraft to perform an interplanetary flight and the first to fly past Venus, as part of the Soviet Union's Venera programme. Launched in February 1961, it was intended as an impactor, but flew past Venus on 19 May of the same year; however, radio contact with the probe was lost before the flyby, resulting in it returning no data.

Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" among the planets of the Solar System for its orbit being the closest to Earth's, both being rocky planets and having the most similar and nearly equal size and mass. Venus, though, differs significantly by having no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. It is composed of mostly carbon dioxide and has a cloud layer of sulfuric acid that spans the whole planet. At the mean surface level, the atmosphere reaches a temperature of 737 K and a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a supercritical fluid. From Earth Venus is visible as a star-like point of light, appearing brighter than any other natural point of light in Earth's sky, and as an inferior planet always relatively close to the Sun, either as the brightest "morning star" or "evening star".