Venus

Earth’s twin in size, and the hottest planet in the solar system.

Venus is the second planet from the Sun and the closest in size to Earth. Under its thick clouds, though, it is a crushing, scorching world where a runaway greenhouse effect keeps the ground hotter than Mercury’s.

How big is Venus compared with Earth?

Venus has a diameter of about 12,104 km, 95% of Earth’s. Its mass is about 4.87 × 10²⁴ kg, roughly 81.5% of Earth’s, and its density of 5.24 g/cm³ suggests a similar mix of rock and iron inside.

Surface gravity is 8.87 m/s², about 90% of Earth’s, so you would weigh only a little less there. This close match is why Venus is often called Earth’s twin. The resemblance stops at the size.

How far is Venus from the Sun and from Earth?

Venus orbits at an average of about 108.2 million km (0.72 AU) from the Sun. Its orbit is the most circular of any planet, varying only between about 107.5 and 108.9 million km.

Venus comes closer to Earth than any other planet, to roughly 38 million km when it passes between us and the Sun. Averaged over time, though, Mercury is closer to Earth, because Venus spends long stretches on the far side of the Sun.

How long is a day on Venus?

A Venus year lasts 224.7 Earth days. Venus spins very slowly, once every 243 Earth days, so a single rotation takes longer than a whole orbit. It also turns backwards (retrograde) compared with most planets, so on Venus the Sun would rise in the west.

Combining the slow backwards spin with its orbit gives a solar day, sunrise to sunrise, of about 117 Earth days. Why Venus spins this way is not settled. A giant impact or the drag of its heavy atmosphere are both possible causes. Days and years explains the difference between the two kinds of day.

What is the atmosphere of Venus like?

The atmosphere is about 96.5% carbon dioxide and 3.5% nitrogen. It is so massive that the pressure at the surface is about 92 times Earth’s, similar to being 900 metres under the sea.

All that carbon dioxide traps heat. The average surface temperature is about 464 °C, hot enough to melt lead, and it barely changes between day and night or between the equator and the poles. Venus is hotter than Mercury even though it is almost twice as far from the Sun.

Clouds of sulphuric acid

Thick clouds of sulphuric acid droplets cover the planet at about 45 to 70 km up. They reflect most of the sunlight, which makes Venus bright in our sky but hides the surface from ordinary cameras. The cloud tops race around the planet in about four Earth days, far faster than the ground turns, an effect called super-rotation.

In 2020 a team reported phosphine gas in the clouds, a possible sign of life. Later studies questioned the detection, and it remains disputed.

What is the surface of Venus like?

Radar can see through the clouds, and it shows a world shaped by volcanoes. About 80% of the surface is volcanic plains, and there are thousands of volcanoes, including Maat Mons, pictured above. The highest mountains, Maxwell Montes, rise about 11 km above the average level.

Venus has relatively few craters, which suggests much of its surface was repaved by lava within roughly the last 300 to 600 million years. How that happened, and whether volcanoes are still erupting today, is still debated, although Magellan images reanalysed in 2023 showed a vent that appears to have changed shape. Venus has no moons and no global magnetic field.

Which missions have explored Venus?

• Mariner 2 (NASA, 1962): the first spacecraft to fly past another planet successfully.
• Venera 7 (USSR, 1970): the first craft to send data from the surface of another planet.
• Venera 9 (1975) and Venera 13 (1982): returned the first black-and-white and then colour pictures of the surface. Landers survived only about one to two hours.
• Pioneer Venus (NASA, 1978): an orbiter plus probes dropped into the atmosphere.
• Magellan (NASA, 1990 to 1994): mapped about 98% of the surface by radar.
• Venus Express (ESA, 2006 to 2014) and Akatsuki (JAXA, 2015 to 2024): studied the atmosphere and weather from orbit.

Several new missions are planned for the 2030s, including ESA’s EnVision and NASA’s DAVINCI and VERITAS, though their launch dates depend on funding. Many spacecraft also use Venus for gravity assists on the way to other targets.

Can you see Venus from Earth?

Yes, easily. After the Moon, Venus is the brightest natural object in the night sky, reaching about magnitude -4.6. You see it in the west after sunset as the “evening star” or in the east before sunrise as the “morning star”, never more than about 47° from the Sun.

Through binoculars or a small telescope you can watch it go through phases like the Moon, from a small full disc to a large thin crescent. Galileo saw these phases in 1610, and they helped show that the planets orbit the Sun. Transits of Venus across the Sun are rare: the last were in 2004 and 2012, and the next is in December 2117. The night sky guide and orrery show where to look.

Explore it in the orrery

Data sources

• NASA NSSDCA Planetary Fact Sheet
• JPL SSD: Planetary Physical Parameters
• NASA NSSDCA Venus Fact Sheet
• NASA Science: Venus Facts
• ESA: Venus Express