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 is radically different from Earth in other respects.It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide.ith a mean surface temperature of 735 K (462 Â°C; 863 Â°F), Venus is by far the hottest planet in the Solar System, even though Mercury is closer to the Sun. 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.