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Which planet is closest in size and density to Earth?

  1. Mars

  2. Venus

  3. Mercury

  4. Saturn

The correct answer is: Venus

The planet that is closest in size and density to Earth is Venus. Both Earth and Venus are often referred to as "sister planets" due to their similar physical characteristics. In terms of size, Venus has a diameter of about 12,104 kilometers, while Earth's diameter is approximately 12,742 kilometers, making them nearly the same size. Furthermore, the density of Venus is about 5.243 grams per cubic centimeter, which is very close to Earth's density of 5.513 grams per cubic centimeter. This similarity in both size and density indicates that they share a comparable composition and structure, primarily consisting of rock and metal. Additionally, Venus has a similar gravitational force, surface conditions, and atmospheric composition compared to Earth, although it has a much denser atmosphere filled with carbon dioxide and clouds of sulfuric acid. These factors contribute to its status as the closest planetary counterpart to Earth in our solar system. The other planets listed differ significantly from Earth in either size or density. For instance, Mars is smaller and has a lower density, while Mercury is considerably smaller and less dense. Saturn, being a gas giant, has a vastly different composition, size, and density compared to Earth.