Venus is the second planet from the Sun and Earth’s closest planetary neighbor in both distance and size. It orbits the Sun every 225 Earth days and spins slowly in the opposite direction to most planets, completing one rotation in about 243 Earth days, which is longer than its year. Thick clouds of sulfuric acid obscure its surface, producing an intense runaway greenhouse effect that makes it the hottest planet, with surface temperatures around 460°C. This profile explains Venus’s basic characteristics, how it formed and evolved, and how it compares to Earth and other terrestrial planets in the Solar System.
Orbit and Rotation
Venus follows a nearly circular orbit at an average distance of about 108 million kilometers from the Sun, placing it between Mercury and Earth. Its orbital period is roughly 224.7 Earth days. Unlike most planets, Venus rotates retrograde, meaning it spins east to west. A sidereal rotation takes about 243 Earth days, while a solar day, the interval from one noon to the next, lasts about 117 Earth days due to its slow spin combined with orbital motion. Venus’s rotation is so slow and in the opposite sense that the Sun rises in the west and sets in the east.
Physical Properties
Venus has a similar bulk composition to Earth, making it a terrestrial planet with a silicate mantle surrounding a metal core. Its radius is about 6,052 kilometers, approximately 0.95 times Earth’s, and its mass is roughly 0.815 Earth masses. These values make Venus the most Earth-like planet in size and mass. Yet its dense atmosphere, composed mainly of carbon dioxide with clouds of sulfuric acid, drives crushing surface pressures about 92 times that of Earth at sea level. Gravity at the surface is comparable to Earth’s, about 8.87 meters per second², roughly 90 percent of Earth’s gravity.
Physical Parameters at a Glance
| Parameter | Verified Detail | Source Type |
|---|---|---|
| Semi-major axis | 108.2 million kilometers | NASA Planetary Fact Sheet |
| Orbital period | 224.7 Earth days | NASA Planetary Fact Sheet |
| Rotation period (sidereal) | 243 Earth days | NASA Planetary Fact Sheet |
| Equatorial radius | 6,052 kilometers | NASA Planetary Fact Sheet |
| Mass | 4.87 × 10^24 kilograms | NASA Planetary Fact Sheet |
| Surface gravity | 8.87 m/s² | NASA Planetary Fact Sheet |
| Average surface temperature | 735 K (460°C) | Multiple spacecraft measurements |
| Surface pressure | ≈92 bar | In situ probe data |
Atmosphere and Climate
Venus’s atmosphere is extremely dense and dominated by carbon dioxide, with nitrogen making up most of the remainder. Sulfur dioxide, water vapor, and trace gases form global layers of clouds that reflect about 75 percent of incoming sunlight, giving Venus its bright appearance. The thick CO2 envelope traps infrared radiation, producing surface temperatures hot enough to melt lead and tin. Winds in the upper atmosphere circle the planet every four Earth days in a phenomenon called superrotation, while at the surface the air is nearly still. The clouds are composed of sulfuric acid droplets, creating highly corrosive conditions that would destroy most spacecraft over time.
Surface and Geology
Despite the clouds, radar missions have mapped much of Venus’s surface, revealing vast volcanic plains, large shield volcanoes, and complex tectonic features. No active plate tectonics like Earth’s operates on Venus, but the planet has experienced widespread volcanic resurfacing in the past. Two large highland regions, Ishtar Terra and Aphrodite Terra, rise above the plains. Impact craters are relatively sparse, indicating a young surface renewed by lava flows within the last few hundred million years. Models suggest Venus may have lost its surface water early in its history, contributing to the runaway greenhouse state seen today.
Exploration History
More than 40 spacecraft have visited Venus since the 1960s, including flybys, orbiters, and landers from the Soviet Union, the United States, and international partners. The Soviet Venera series achieved multiple soft landings in the 1970s and 1980s, returning images and data from the surface before being crushed by pressure and heat. NASA’s Magellan orbiter produced the first high-resolution global radar maps in the early 1990s, while the Japanese Akatsuki mission continues to study the atmosphere and weather. Upcoming missions from space agencies aim to investigate Venus’s geology, cloud processes, and potential signs of past habitability.
Venus in Context: Terrestrial Planets
Compared to Mercury, Earth, and Mars, Venus occupies a similar size and location range as Earth, yet its climate and geology diverged dramatically. Its thick carbon dioxide atmosphere and lack of a magnetic field distinguish it from Earth, despite similarities in bulk composition. Understanding Venus helps scientists model how terrestrial planets evolve, how atmospheres can shift from temperate to extreme, and what factors control long-term climate stability. Future missions will test whether Venus ever had temperate conditions or surface oceans, shedding light on planetary habitability across systems.
Observing Venus From Earth
Venus is often visible in the evening sky after sunset or the morning sky before sunrise, earning it the titles Evening Star and Morning Star. Its brightness, second only to the Moon among nighttime objects, comes from its thick clouds reflecting sunlight. Because its orbit lies inside Earth’s orbit, Venus shows phases similar to the Moon as viewed from Earth. Amateur astronomers with small telescopes can observe these phases, and transits of Venus across the Sun, though rare, have historically played important roles in measuring the scale of the Solar System.