Earth's scorching twin
Venus
Venus is the second planet from the Sun and Earth's nearest planetary neighbour. In size and mass it is almost Earth's twin, which is why it was once imagined as a warm, swampy world hidden beneath its clouds.
The reality is far more hostile. Venus has the hottest surface of any planet, an atmosphere so dense that standing on the ground would feel like being nearly a kilometre under the sea, and clouds laced with sulfuric acid. It is a vivid example of how a planet similar to Earth can end up radically different.
Key facts
- Diameter
- 12,104 km0.95× Earth
- Mass
- 4.87 × 10²⁴ kg0.82× Earth
- Gravity
- 8.9 m/s²0.91 g
- Mean distance from Sun
- 0.72 AU≈ 108 million km
- Length of year
- 224.7 dEarth days or years
- Length of day
- 116.8 dSunrise to sunrise
- Mean temperature
- 464°CAt the surface
- Known moons
- None
- Axial tilt
- 177.4°
1 astronomical unit (AU) is Earth's average distance from the Sun, about 149.6 million km. Values follow the NASA Planetary Fact Sheet; many are averages and vary with how and where they are measured.
Physical characteristics
Venus is 12,104 km across, about 95% of Earth's diameter, and has about 82% of Earth's mass. Its surface gravity, 8.9 m/s², is roughly 91% of ours, so you would feel only slightly lighter there.
From Earth, Venus is the brightest natural object in the night sky after the Moon. Its thick clouds reflect around three-quarters of the sunlight that hits them, which is why it shines so brilliantly as the 'morning star' or 'evening star'.
Atmosphere and climate
The atmosphere is about 96.5% carbon dioxide and 3.5% nitrogen, with a surface pressure of about 92 bar — 92 times the air pressure at sea level on Earth. That huge blanket of CO₂ drives a runaway greenhouse effect that holds the surface at about 464°C, hot enough to melt lead, day and night and from the equator to the poles.
Thick cloud decks between roughly 45 and 70 km altitude are made of sulfuric acid droplets. At the cloud tops, winds 'super-rotate' around the planet at about 360 km/h, circling Venus in roughly four Earth days even though the solid surface takes 243 days to turn once.
Composition: CO₂ 96.5% · N₂ 3.5% · sulfuric acid clouds
Surface and interior
A volcanic world
Radar maps from NASA's Magellan orbiter revealed a surface dominated by volcanic plains, thousands of volcanoes and vast lava flows. Maxwell Montes, the highest mountain range, rises about 11 km above the average surface level.
A young face
Venus has relatively few impact craters, and they are spread fairly evenly. Scientists interpret this as a sign that much of the surface was resurfaced by volcanism within the last several hundred million years — geologically recent, though how that happened is still debated.
Is it still active?
Re-analysis of Magellan radar images published in 2023 found a volcanic vent that appeared to change shape over eight months, one of the strongest hints that Venus may still be volcanically active today.
Inside Venus
Venus is thought to have an iron core, rocky mantle and crust broadly like Earth's, but it has no measurable global magnetic field — possibly because its very slow rotation or internal structure prevents a dynamo from running.
Moons and rings
Venus has no moons and no rings. Mercury and Venus are the only planets without a natural satellite.
Orbit and rotation
Venus follows the most circular orbit of any planet, averaging 0.72 AU — about 108 million km — from the Sun, and completes it every 224.7 Earth days.
It also spins backwards compared with most planets, a motion called retrograde rotation, so the Sun rises in the west and sets in the east. One rotation takes 243 Earth days, longer than its year. Combining the slow backwards spin with its orbital motion gives a solar day of about 117 Earth days.
Exploration and missions
Venus was the first planet visited by a spacecraft and the first on which one landed — though no lander has survived its surface for more than about two hours.
- 1962
Mariner 2 · NASA
The first successful flyby of another planet, confirming Venus's extreme heat.
- 1970
Venera 7 · USSR
The first spacecraft to transmit data from the surface of another planet.
- 1975
Venera 9 · USSR
Returned the first images from the surface of another planet.
- 1990–1994
Magellan · NASA
Mapped about 98% of the surface with radar, revealing its volcanic landscape.
- 2006–2014
Venus Express · ESA
Studied the atmosphere and super-rotating winds in detail.
- 2015–2024
Akatsuki · JAXA
Studied Venus's weather and atmospheric dynamics from orbit.
- 2030s
DAVINCI, VERITAS & EnVision · NASA / ESA
Planned missions to probe the atmosphere and map the surface in unprecedented detail.
Surprising facts about Venus
- A day on Venus (one rotation) is longer than its year.
- The Sun rises in the west on Venus.
- Its surface is hotter than Mercury's, even though it is almost twice as far from the Sun.
- The surface pressure is similar to the water pressure about 900 m below the ocean surface on Earth.
- The longest-surviving lander, the Soviet Venera 13, lasted 127 minutes in 1982.
Venus compared with Earth
| Property | Venus | Earth |
|---|---|---|
| Diameter | 12,104 km | 12,756 km |
| Mass (Earth = 1) | 0.816 | 1.000 |
| Gravity | 0.91 g | 1.00 g |
| Day | 116.8 d | 24.0 h |
| Year | 224.7 d | 365.2 d |
| Mean temperature | 464°C | 15°C |
| Moons | 0 | 1 |
Keep exploring
- Earth: the ocean world that supports life
- Mercury: the swift, scorched innermost world
- Mars: the red planet
- BepiColombo — two orbiters bound for mercury
- JUICE — europe's explorer of jupiter's icy moons
- Parker Solar Probe — the spacecraft that touched the sun
- Solar Orbiter — the first views of the sun's poles
- Fly to Venus in the interactive 3D solar system
- All eight planets of the Solar System