Because the surface is hidden by sulphuric acid clouds, and the planet is similar to the Earth in size, astronomers speculated for many years that Venus might be a lush world full of life.
It is now thought possible that the Sun's heat boiled away early oceans on the planet triggering a planet-warming runaway greenhouse effect that turned Venus into a hellish place.
Photo: A false-colour view of Venus taken by the Galileo probe. This photo was coloured blue to show details in Venus's clouds. (NASA/JPL)
The second planet from the Sun is a pressure cooker.
Enjoy Astronomer Marek Kukula's guide to the Solar System.
If Jupiter were much larger it would be a star in its own right! Enjoy Astronomer Marek Kukula's eloquent guide to the Sun, the planets and the outer reaches of the Solar System.
Lynn Rothschild explains how the Earth's orbit makes it special.
Dr Lynn Rothschild explains how the Earth is located in the habitable zone of the Sun, an orbit that permits liquid water to exist. Astronomers hope to find planets similar to the Earth in the habitable zones of other stars as part of their search for places where life could exist.
Learn how to remember all the planets of the Solar System in order.
Here’s an animated guide to remembering all the planets of the Solar System in order, using an easy mnemonic trick.
Brian Cox looks at what makes the two planets so different.
Professor Brian Cox looks at how greenhouse gases made Earth and Venus so different today.
The Russians take the first photograph of the planet's surface.
After a series of Venera missions, the Russians built Venera 9, a craft capable of withstanding Venus's searing temperatures and crushing pressures long enough to send back a picture of the surface. Venera 9's 1975 photograph of Venus showed a surface strewn with volcanic rocks.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has no natural satellite. It is named after the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°.
Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). However, it has also been shown to be radically different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet's surface is 92 times that of Earth's. With a mean surface temperature of 735 K (462 °C; 863 °F), Venus is by far the hottest planet in the Solar System. It has no carbon cycle to lock carbon back into rocks and surface features, nor does it seem to have any organic life to absorb it in biomass. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. Venus may have possessed oceans in the past, but these would have vaporized as the temperature rose due to a runaway greenhouse effect. The water has most probably photodissociated, and, because of the lack of a planetary magnetic field, the free hydrogen has been swept into interplanetary space by the solar wind. Venus's surface is a dry desertscape interspersed with slab-like rocks and periodically refreshed by volcanism.