The planet often referred to as Earth's twin is Venus. This nickname arises from Venus's similar size, mass, and composition to Earth, making it one of our closest neighbors in the solar system. However, the two planets have vastly different environments; Venus has a thick, toxic atmosphere composed mainly of carbon dioxide, with sulfuric acid clouds and extreme surface temperatures averaging around 465 degrees Celsius (869 degrees Fahrenheit). This harsh climate makes it inhospitable to life as we know it. Despite these differences, studying Venus helps scientists understand planetary evolution and the potential for life elsewhere in the universe.