Venus

Venus is often called Earth’s twin because it is similar in size and mass, yet it is one of the most hostile planets in the solar system. Thick clouds of sulfuric acid completely hide its surface, and it has the hottest average temperature of any planet — hot enough to melt lead.

Venus is the second planet from the Sun. Its thick atmosphere creates an extreme greenhouse effect that traps heat, pushing surface temperatures to around 900°F (465°C). This makes Venus hotter than Mercury, even though it is farther from the Sun.

Atmosphere and Surface

The atmosphere of Venus is made mostly of carbon dioxide, with thick clouds of sulfuric acid droplets. The pressure at the surface is about 92 times greater than Earth’s sea-level pressure — the same as being nearly a mile underwater on Earth.

Radar mapping from spacecraft has revealed a surface covered with vast volcanic plains, lava flows, and thousands of volcanoes. Some volcanoes may still be active today. The planet also has strange, flat-topped features called “pancake domes” and long, winding channels that were likely carved by lava.

Key Facts About Venus

Diameter: 7,521 miles (12,104 km) — slightly smaller than Earth
Mass: 0.815 times Earth’s mass
Distance from the Sun: 67 million miles (0.72 AU) on average
Day Length: 243 Earth days (rotates backwards)
Year Length: 225 Earth days
Surface Temperature: ~900°F (465°C) everywhere

Rotation and Extreme Conditions

Venus rotates very slowly and in the opposite direction to most planets — a phenomenon called retrograde rotation. One day on Venus is longer than one year on Venus. The planet has no moons and no global magnetic field to protect it from solar wind.

Because of its thick atmosphere, the surface cannot be seen with visible light. Scientists have used radar and infrared instruments to map the planet in detail. Missions such as NASA’s Magellan and the European Space Agency’s Venus Express have revealed a young surface that appears to have been completely resurfaced by volcanic activity hundreds of millions of years ago.

Venus serves as a warning about runaway greenhouse effects. Its extreme conditions help scientists understand how planetary atmospheres can change dramatically over time. Future missions plan to study its atmosphere and surface more closely to learn why two planets that started so similarly ended up so different.

With crushing pressure, scorching heat, and acid clouds, Venus stands as one of the most dramatic examples of how different a rocky planet can become depending on its distance from the Sun and the composition of its atmosphere.