Venus

Venus is often called Earth’s “sister planet” because it’s nearly the same size, mass, and density. However, the similarities stop there. Venus is a greenhouse furnace, wrapped in an atmosphere so thick and hot that it crushes and bakes anything that lands on its surface.

The atmosphere is composed of 96% carbon dioxide, with thick clouds of sulfuric acid swirling around the planet. This traps heat and creates surface temperatures up to 475°C (900°F)—hotter than Mercury, even though Venus is farther from the Sun. The pressure on the surface is 90 times greater than Earth’s, equal to standing almost a kilometer below the ocean.

Venus rotates in the opposite direction of most planets, a phenomenon called retrograde rotation. On Venus, the Sun rises in the west and sets in the east. Even more bizarrely, Venus has the slowest rotation in the entire Solar System: one Venusian day lasts 243 Earth days, longer than its year of 225 days.

Radar mapping shows a planet covered in vast volcanic plains, mountains, and thousands of volcanoes. Some evidence suggests that Venus may still be volcanically active today, with new lava flows forming within the last few decades. Despite its deadly environment, Venus is crucial to understanding how greenhouse effects shape planetary climates.