Venus is the second planet from the Sun and Earth's closest planetary neighbor. It is about 12,100 kilometers (7,520 miles) across, 95% as wide as Earth. Venus is almost perfectly round, so that width is the same through the equator as from pole to pole.

Size

NASA gives Venus a mean radius of 6,051.8 kilometers, which makes it 12,104 kilometers across. NASA lists the same radius at the equator and at the poles. Earth, by comparison, is about 43 kilometers wider at the equator than from pole to pole.

Dense clouds hide the surface, so NASA's Magellan spacecraft mapped it with radar, in a mission that ended in 1994. Venus has about 81% of Earth's mass, and gravity at its surface is about 90% as strong as on Earth. Venus is similar to Earth in size and structure, and NASA notes that it is sometimes called "Earth's evil twin."

Size comparisons

• Earth, the next larger object in the explorer, is about 5% wider than Venus. By volume, Venus is about 86% the size of Earth.
• Sirius B, the next smaller object in the explorer, is a white dwarf star about 11,300 kilometers (7,020 miles) across. Venus is about 7% wider than that star.
• Venus is about 1.8 times as wide as Mars and about 3.5 times as wide as the Moon.
• If the Sun were shrunk to the size of a basketball, Venus would be a bead about 2 millimeters across, about 19 meters (61 feet) from the ball. Earth would be a bead of almost the same size, about 26 meters (85 feet) away.

The hottest planet

Venus is the hottest planet in the Solar System, hotter even than Mercury, which is closer to the Sun. Its surface is about 467 °C (872 °F), hot enough to melt lead. The thick atmosphere, mostly carbon dioxide, traps heat in what is called a runaway greenhouse effect. Above the surface float clouds of sulfuric acid.

At the surface, the air presses down about 93 times as hard as it does at sea level on Earth. That is like being more than 930 meters (3,000 feet) under water. The Soviet Union sent a series of Venera probes between 1961 and 1984. Ten reached the surface, and the longest-lasting one worked for two hours.

A day longer than a year

Venus turns very slowly, and backward compared with most planets. One turn takes 243 Earth days, longer than the 225 days it takes to go around the Sun. Seen from the surface, the Sun would rise in the west and set in the east. Because Venus turns and orbits at the same time, one day from sunrise to sunrise lasts about 117 Earth days.

Seen from Earth

From Earth, Venus is the brightest object in the night sky after the Moon. Watched through a telescope over many months, it shows phases like the Moon's. Galileo's observations of these phases were key evidence that the planets orbit the Sun.

Sources

• Venus Fact Sheet. NASA, 2024.
• Venus Facts. NASA, 2026.
• Earth Fact Sheet. NASA, 2024.
• The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry. Bond et al., The Astrophysical Journal, 2017.
• Mars Fact Sheet. NASA, 2025.
• Moon Fact Sheet. NASA, 2024.
• Sun Fact Sheet. NASA, 2024.
• Official Basketball Rules 2026: Basketball Equipment. FIBA, 2026.