Venus

Venus is the second planet from the Sun and one of the most extreme worlds in the solar system. Often called Earth’s twin because of its similar size and mass, Venus is actually a scorching, hostile planet hidden beneath thick clouds of toxic gas.

Despite being farther from the Sun than Mercury, Venus is the hottest planet in the solar system.

A Runaway Greenhouse World

The intense heat on Venus is caused by a runaway greenhouse effect.

Its atmosphere is made mostly of carbon dioxide, a gas that traps heat extremely effectively. Thick clouds surrounding the planet prevent heat from escaping into space, causing surface temperatures to soar to around 900°F (465°C).

This temperature is hot enough to melt lead.

Atmosphere and Pressure

Venus has one of the densest atmospheres of any rocky planet.

The atmosphere consists mainly of:

• Carbon dioxide (~96%)
• Nitrogen
• Sulfuric acid clouds

The pressure at the surface is about 92 times stronger than Earth’s — similar to the pressure found nearly a mile underwater on Earth.

The thick atmosphere completely hides the surface from normal visible-light observation.

The Surface of Venus

Because the surface is hidden beneath clouds, scientists use radar mapping to study Venus.

Spacecraft have revealed a landscape dominated by:

• Vast volcanic plains
• Lava flows
• Massive shield volcanoes
• Impact craters
• Strange pancake-shaped volcanic domes

Some evidence suggests that volcanoes on Venus may still be active today.

Unlike Earth, Venus has no plate tectonics. Instead, heat may build beneath the crust until large regions are resurfaced by enormous volcanic eruptions.

Key Facts About Venus

Diameter: 7,521 miles (12,104 km)
Mass: 0.815 Earth masses
Average Distance from the Sun: 67 million miles (0.72 AU)
Day Length: 243 Earth days
Year Length: 225 Earth days
Average Surface Temperature: ~900°F (465°C)

Retrograde Rotation

Venus rotates in the opposite direction of most planets.

This unusual motion is called retrograde rotation.

On Venus:

• The Sun rises in the west
• The Sun sets in the east
• A single day lasts longer than an entire Venusian year

Scientists are still uncertain why Venus rotates this way, though ancient collisions or gravitational interactions may be responsible.

No Moons and No Magnetic Field

Venus has no moons and lacks a strong global magnetic field.

Without magnetic protection, solar wind directly interacts with the upper atmosphere. Even so, the planet’s dense atmosphere remains largely intact because of its enormous mass and gravity.

Exploration of Venus

Venus has been explored by many robotic spacecraft.

Notable missions include:

• NASA’s Magellan mission
• ESA’s Venus Express
• Soviet Venera landers

The Venera missions achieved one of the greatest engineering feats in planetary science by landing on the surface and transmitting images before being destroyed by the extreme heat and pressure.

Future missions aim to study:

• Atmospheric chemistry
• Possible volcanic activity
• Climate evolution
• Ancient water history

Why Venus Matters

Venus provides a powerful example of how planetary climates can evolve dramatically.

Scientists believe Venus may once have had oceans and more Earth-like conditions billions of years ago before the greenhouse effect spiraled out of control.

Studying Venus helps researchers understand:

• Climate change
• Atmospheric evolution
• Runaway greenhouse effects
• How rocky planets develop over time

Earth’s Dangerous Twin

Although Venus and Earth began with similar sizes and compositions, they evolved into radically different worlds.

Earth became a planet filled with oceans and life.

Venus became a furnace hidden beneath crushing clouds.

This dramatic contrast makes Venus one of the most important planets for understanding both the fragility and rarity of habitable worlds in the universe.