Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never far from the Sun, either as morning star or evening star. Aside from the Sun and Moon, Venus is the brightest natural object in Earth's sky, capable of casting visible shadows on Earth at dark conditions and being visible to the naked eye in broad daylight.Venus is the second largest terrestrial object of the Solar System, with a surface gravity minimally lower than on Earth, but having only an induced magnetosphere. The carbon dioxide atmosphere of Venus is the densest of the four terrestrial planets. The atmospheric pressure at the planet's surface is about 92 times the sea level pressure of Earth, or roughly the pressure at 900 m (3,000 ft) underwater on Earth. Even though Mercury is closer to the Sun, Venus has the hottest surface of any planet in the Solar System, with a mean temperature of 737 K (464 C; 867 F). Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, making it the planet with the highest albedo in the Solar System and preventing its surface from being seen from Earth in light. It may have had water oceans in the past, but after these evaporated the temperature rose under a runaway greenhouse effect. The water has probably photodissociated, and the free hydrogen has been swept into interplanetary space by the solar wind because of the lack of an internally induced magnetic field. At roughly 50 km above the surface atmospheric conditions reach Earth-like temperatures and levels of pressure. The possibility of life on Venus has long been a topic of speculation but convincing evidence has yet to be found.

Venus does not have any moons, a distinction it shares only with Mercury among the planets in the Solar System. Solar days on Venus, with a length of 117 Earth days, are just about half as long as its solar year, orbiting the Sun every 224.7 Earth days. This Venusian daylength is a product of it rotating against its orbital motion, halving its full sidereal rotation period of 243 Earth days, the longest of all the Solar System planets. Venus and Uranus are the only planets with such a retrograde rotation, making the Sun move in their skies from their western horizon to their eastern. The orbit of Venus around the Sun is the closest to Earth's orbit, allowing them to approach each other at inferior conjunction closer than any other planet, at a synodic period of 1.6 years, while Mercury approaches them more often the closest. The close orbit of Venus and Earth furthermore results in the lowest gravitational potential difference and lowest delta-v needed to transfer from them to any other planet.

This has made Venus a prime target for early interplanetary exploration. It was the first planet beyond Earth spacecrafts were sent towards (Venera 1 in 1961) and the first to be reached, impacted and successfully landed on (by Venera 7 in 1970). As one of the brightest objects in the sky, Venus has been a major fixture in human culture for as long as records have existed. It has been made sacred to gods of many cultures, gaining its mainly used name from the Roman goddess of love and beauty which it is associated with. Furthermore it has been a prime inspiration for writers, poets and scholars. Venus was the first planet to have its motions plotted across the sky, as early as the second millennium BCE. Plans for better exploration with rovers or atmospheric missions, potentially crewed, at levels with almost Earth-like conditions have been proposed.

Venera 7 (Russian: Венера-7, lit. 'Venus 7') was a Soviet spacecraft, part of the Venera series of probes to Venus. When it landed on the Venusian surface on 15 December 1970, it became the first spacecraft to soft land on another planet and the first to transmit data from there back to Earth.