Venus

Venus is almost the same size as Earth, earning it the nickname “Earth's twin,” yet its thick carbon dioxide atmosphere makes it the hottest planet in the Solar System. It even spins backward, so the Sun rises in the west.

What kind of planet is it?

Venus is the second planet from the Sun, orbiting at an average distance of about 0.72 AU. It's about 12,104 km across, roughly 95% of Earth's diameter, and its mass and surface gravity (about 0.9 times Earth's) are very similar to ours. That's why it has long been called Earth's twin.

Like Earth, Venus is thought to be a rocky planet with an iron core, a rocky mantle and a crust. Most of its surface is covered by vast volcanic plains, with countless volcanoes and traces of old lava flows. Its highest range, Maxwell Montes, rises about 11 km, higher than Mount Everest. Venus has relatively few craters, which suggests its entire surface may have been repaved by volcanic activity a few hundred million years ago.

Venus's strangest trait is its spin. It rotates very slowly in the opposite direction to most planets, taking about 243 days to turn once. Since its year is about 224.7 days, one rotation takes longer than a year! Combining spin and orbit, a full day from sunrise to sunrise (a solar day) lasts about 117 days. Its axial tilt of 177.4° is another way of saying it spins almost upside down.

Atmosphere and weather

Venus is wrapped in an extremely thick atmosphere: about 96% carbon dioxide, with most of the rest nitrogen. The pressure at the surface is about 90 times Earth's, similar to what you'd feel about 900 m deep in Earth's oceans.

Carbon dioxide traps heat in an extreme greenhouse effect, pushing the average surface temperature to about 464°C (867°F). That's hotter than Mercury, even though Mercury is closer to the Sun, making Venus the hottest planet in the Solar System. Because the dense atmosphere spreads heat so evenly, there's almost no temperature difference between day and night or between the equator and the poles.

The sky is permanently covered by sulfuric acid clouds about 50–70 km up. These clouds reflect sunlight strongly, which makes Venus shine so brightly, but they also hide the surface from view in space. High up, winds blow far faster than the planet rotates, carrying the cloud layer around Venus in about four days. This is called super-rotation. Near the surface, by contrast, the winds are sluggish.

Moons and rings

Venus has no moons and no rings. Along with Mercury, it's one of only two moonless planets. Why it has no moon still isn't settled, and scientists are studying several ideas, such as whether a big impact or similar event happened in the past.

A small asteroid has been found near Venus that circles the Sun in almost the same time Venus does. Objects like this are called quasi-satellites, but they don't actually orbit Venus the way a true moon would.

Exploration

As the planet that comes closest to Earth, Venus has a long history of exploration. But its heat and crushing pressure made it very hard for landers to survive for long.

• Mariner 2 (USA, 1962): Flew past Venus and became the first successful flyby of another planet. It also confirmed that the surface is extremely hot.
• Venera program (Soviet Union, 1960s–1980s): In 1970, Venera 7 landed on Venus and sent the first signals ever received from the surface of another planet. In 1975, Venera 9 returned the first images of the surface, and in 1982 Venera 13 sent back color images. The landers lasted a little over two hours at most in the brutal conditions.
• Magellan (USA, launched 1989): Orbited Venus from 1990 to 1994, using radar to see through the clouds and mapping about 98% of the surface.
• Venus Express (Europe, 2006–2014) and Akatsuki (Japan, entered orbit 2015): Studied Venus's atmosphere, clouds and winds in detail.

New missions such as NASA's DAVINCI and VERITAS and Europe's EnVision are planned to return to Venus in the future.

Fun facts

• Apart from the Sun and the Moon, Venus is the brightest object in the sky. When it shines in the east before dawn it's called the Morning Star, and in the west after sunset, the Evening Star.
• On Venus, the Sun rises in the west and sets in the east, although the thick clouds mean you couldn't see it clearly from the surface.
• One rotation of Venus (about 243 days) is longer than its year (about 224.7 days).
• Almost all features on Venus are named after real or mythological women. Maxwell Montes is one of only a few exceptions.
• About 50 km above Venus, the pressure and temperature are similar to Earth's, so it's sometimes imagined as a site for floating outposts in the far future.

See it in Planetica

In Solar System view, Venus appears on the second orbit from the Sun, just outside Mercury. Its position is calculated from J2000 orbital elements for today's date, so you can compare which side of the Sun Venus is on relative to Earth right now. If Venus and Earth are close together on the same side of the Sun, Venus really is near Earth at the moment.

Pick Venus and fly in close to see just how similar in size it is to Earth. Values such as day length, axial tilt (177.4°), average temperature and orbital period are based on real data. It has no moons or rings.

The surface pattern is drawn by Planetica's planet generator to suit the planet type. The real Venus looks like a ball of yellowish cloud from space, and the volcanic terrain mapped by radar is also different from the patterns in the app.

Other planets

← MercuryEarth →

• Mercury
• Venus
• Earth
• Mars
• Jupiter
• Saturn
• Uranus
• Neptune