In the early 1970s, NASA sent Mariner 10 past Venus. In 1974, the probe returned around 4,000 pictures of the planet. In this image, Venus has been color-enhanced to show what it would look like to the human eye. Here you can see the clouds of carbon dioxide enshrouding the planet, where temperatures can reach as high as 900 degrees Fahrenheit. Despite its inhospitable climate, the planet is known as Earth's "twin" as it is also a terrestrial planet that is just smaller than our home world.