Venus

Venus is the second planet from the Sun and the brightest natural object in Earth's night sky after the Moon, often called the Evening Star or Morning Star depending on its position in its orbit. Named after the Roman goddess of love and beauty, Venus is a terrestrial planet similar in size and composition to Earth, yet its surface conditions are among the most hostile in the Solar System.

Physical characteristics

Venus has a mean radius of approximately 6,051 kilometres, making it only slightly smaller than Earth. Its mass is about 81.5 percent of Earth's, and its surface gravity is roughly 90 percent of Earth's, meaning a person standing on Venus would feel nearly the same gravitational pull as on Earth.

Surface

The Venusian surface is dominated by vast volcanic plains, highland regions called terrae, and thousands of volcanoes. The largest highland region, Aphrodite Terra, stretches across the equatorial zone and rivals the size of Africa. Radar mapping by the Magellan spacecraft (1990–1994) revealed a geologically young surface, with widespread evidence of past and possibly ongoing volcanism. Surface temperatures average around 465 °C (869 °F), hot enough to melt lead, largely due to a runaway greenhouse effect.

Atmosphere

The Venusian atmosphere is composed of approximately 96.5 percent carbon dioxide, with the remainder being mostly nitrogen and trace amounts of sulfur dioxide and other gases. Atmospheric pressure at the surface is about 92 times that of Earth at sea level, equivalent to the pressure at roughly 900 metres depth in Earth's oceans. Thick clouds of sulfuric acid droplets cover the planet continuously, reflecting about 70 percent of incoming sunlight and making Venus the most reflective planet in the Solar System.

Rotation and orbit

Venus orbits the Sun at an average distance of about 108 million kilometres with an orbital period of approximately 224.7 Earth days. Its rotation is exceptionally slow and retrograde — opposite to the direction of most planets — completing one rotation in about 243 Earth days. This means a Venusian day is longer than a Venusian year. The slow retrograde rotation means the Sun rises in the west and sets in the east on Venus.

Exploration history

Venus has been visited by more spacecraft than any other planet beyond Earth. The former Soviet Union's Venera program conducted the majority of early exploration, achieving the first successful landing on another planet when Venera 7 transmitted data from the Venusian surface in December 1970. Later Venera landers returned the first colour images of the surface in the 1980s.

NASA's Mariner 2 conducted the first successful planetary flyby in December 1962, confirming the extreme surface temperatures. The Magellan spacecraft subsequently produced detailed radar maps of nearly the entire surface between 1990 and 1994. The European Space Agency's Venus Express orbited the planet from 2006 to 2014, studying its atmosphere and climate in detail. Japan's Akatsuki spacecraft entered Venusian orbit in December 2015 and continued atmospheric studies into the 2020s.

Several missions are planned for the late 2020s and 2030s, including NASA's DAVINCI and VERITAS missions and ESA's EnVision, though mission schedules are subject to change and readers should consult current sources for the latest status.

Significance in culture and science

Venus has held cultural significance across many civilisations. The Babylonians tracked its movements as early as 1600 BCE. In ancient Mesoamerican cultures, including the Maya civilisation, Venus held deep calendrical and religious importance. In Western tradition, the planet's association with the goddess of love influenced art, literature, and astronomy from antiquity onward.

Scientifically, Venus serves as a cautionary example of runaway greenhouse warming, making it a key subject of study in climate science and planetary science. Comparisons between Earth and Venus have informed models of atmospheric evolution and the conditions necessary for planetary habitability.

The phosphine controversy

In September 2020, a team of astronomers reported the detection of phosphine in the Venusian atmosphere, a finding that generated significant scientific debate because phosphine on Earth is associated with biological processes. Subsequent reanalysis by multiple teams disputed the strength of the detection signal, and the claim remains contested as of the mid-2020s. No confirmed evidence of life on Venus exists.

Comparison with Earth

Despite similar size, mass, and bulk composition, Venus and Earth diverged dramatically in their atmospheric and surface evolution. Key differences include:

• Venus lacks a global magnetic field, leaving its atmosphere more directly exposed to the solar wind.
• Venus has no confirmed plate tectonics, though evidence of tectonic-like activity is debated among planetary scientists.
• Venus has no natural satellite, whereas Earth has the Moon.
• Water, if ever present in large quantities on Venus, was likely lost over billions of years through a combination of solar radiation and atmospheric escape.

These contrasts make Venus a natural laboratory for understanding what determines whether a terrestrial planet becomes habitable.

Frequently asked questions

Is Venus the hottest planet in the Solar System?

Yes. Although Mercury is closer to the Sun, Venus is hotter because its dense carbon-dioxide atmosphere traps heat through a runaway greenhouse effect, maintaining surface temperatures of around 465 °C on average.

Is Venus visible from Earth without a telescope?

Yes. Venus is the brightest natural object in the night sky after the Moon and is easily visible to the naked eye, appearing as a very bright white point of light near the horizon at sunrise or sunset.

Is a day on Venus longer than a year on Venus?

Yes. Venus rotates so slowly that its sidereal rotation period of about 243 Earth days exceeds its orbital period of about 224.7 Earth days, making a Venusian day longer than a Venusian year.

Is there life on Venus?

No confirmed evidence of life on Venus exists. The 2020 phosphine detection claim, which prompted speculation about microbial life in the cloud layers, remains scientifically disputed and has not been independently confirmed.

Is Venus a terrestrial planet?

Yes. Venus is classified as a terrestrial planet, meaning it has a solid silicate surface and rocky composition, in contrast to the gas and ice giants of the outer Solar System.