Venus is a planet.
Venus is the second planet from the Sun , orbiting it every 224.7 Earth days . Venus is a terrestrial planet and is sometimes called Earth 's `` sister planet '' because of their similar size , mass , proximity to the Sun , and bulk composition . It has the densest atmosphere of the four terrestrial planets , consisting of more than 96 % carbon dioxide . As the closest planet to Earth , Venus has been a prime target for early interplanetary exploration .