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Why is Venus called Earth’s sister planet?
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Venus
Venus photographed in ultraviolet light by the Pioneer Venus Orbiter (Pioneer 12) spacecraft, February 26, 1979. Although Venus's cloud cover is nearly featureless in visible light, ultraviolet imaging reveals distinctive structure and pattern, including global-scale V-shaped bands that open toward the west (left). Added color in the image emulates Venus's yellow-white appearance to the eye.
Venus is often referred to as Earth’s sister planet or twin because of several key physical similarities between the two worlds. These include:123
- Size and Mass: Venus is nearly the same size as Earth, with a mean radius that is about 95 percent of Earth’s. Its mass is approximately 81.5 percent of Earth’s.1
- Density and Composition: Both planets have comparable densities and are believed to have formed from similar rocky building blocks in the solar nebula, suggesting they share a similar overall chemical composition.243
- Internal Structure: Scientists expect that, like Earth, Venus possesses a metallic core, a rocky mantle, and a crust.4
- Location: They share similar relative positions within the solar system.23
Despite these structural parallels, the two planets have evolved into vastly different environments. While Earth supports life, Venus is an extremely hot, dry, and hostile world with a massive carbon dioxide atmosphere that creates an intense greenhouse effect. Studying these differences is essential for understanding environmental change and the factors that make a planet habitable.235