Venus is often called Earth’s sister planet or twin because of 3 major similarities:
Further Venus is the closest planet to Earth within the solar system.
Size
Earths diameter is ##12756.2 km## and Venus’s is ##12103.6 km##. Earth is only ##~~ 5%## larger than Venus which in comparison to other size differences between other surrounding planets is a relatively minute difference in size.
In this image you have to look carefully to notice that Earth (right) is slightly larger:
Mass
As with their sizes the mass of Venus is only slightly lesser than that of EarthEarth weighs only ##~~ 19%## more than Venus does. Even the force of gravity on the 2 planets is close; you’d experience ##90%## of gravity’s force on Earth if you visited Venus.
Composition
Both Venus and Earth have metal cores surrounded by a mantle of silica rock (also common in rocky moons and asteroids) and then a thin crust.
Despite these similarities Earth and Venus are also quite different causing some to nickname Venus Earth’s evil twin.
The major differences are those that make Venus too hostile to support life as Earth does: temperature and atmosphere.
Venus’s average temperature is ##461.85 C## (higher than that of molten lead!) and the atmospheric pressure is 90 times that on Earths surface.
While Earth’s atmosphere is composed of oxygen and nitrogen (with only small amounts of ##CO_2##) Venus atmosphere is ##96.5%## carbon dioxide. Unlike Earth’s fluffy cumulus clouds Venus has clouds of sulphuric acid that rain down on the planet’s surface adding to the planet’s inhospitable environment.