Venus is the second planet from the Sun and the sixth-largest. Venus’ diameter is 12,103.6 kilometers (7,521.4 mi), which makes it slightly smaller than Earth. Venus is similar to Earth in size and mass, and is often referred to as Earth’s “sister planet”. The two planets are similar in structure, but Venus has a much denser atmosphere than Earth. This dense atmosphere consists mostly of carbon dioxide and nitrogen, with clouds of sulfuric acid droplets floating in the upper atmosphere. The surface of Venus is covered with lava flows and volcanoes. There is very little water on Venus, and what does exist exists almost entirely in the form of ice at the poles.
The average temperature on Venus’ surface is 462 degrees Celsius (863 degrees Fahrenheit). This makes it the hottest world in our Solar System – even hotter than Mercury! The high temperatures on Venus are caused by a “runaway greenhouse effect”. This occurs when sunlight warms a planet’s surface, but the thick atmospheric blanket prevents heat from escaping back into space. As more heat builds up, things just get hotter and hotter! On Earth, our oceans help to regulate temperature by absorbing some of this excess heat. But since there’s very little water on Venus, there’s nothing to moderate the intense heat.
Despite its extreme conditions, there is evidence that Venus may have once been habitable for life as we know it. In fact, some scientists have even suggested that life might still exist in venusian clouds! However, any life on Venus would be incredibly different from anything we’re familiar with here on Earth.