Venus is the second planet from the Sun and is often called Earth’s “sister planet” due to its similar size and composition. However, its extreme conditions make it a very different and hostile world. Despite its intense heat and pressure, the study of Venus provides valuable insights into planetary formation, atmospheric processes, and the effects of greenhouse gases. It has no moons.

1. 1. Size and Composition

• • • Diameter: Venus is about 12,104 km (7,521 miles) in diameter, making it only slightly smaller than Earth.
    • Composition: Like Earth, Venus is a terrestrial planet with a rocky surface. It has a dense core made mostly of iron, surrounded by a mantle of silicate rock.

 

1. 2. Orbit and Rotation

• • • Orbit around the Sun: Venus takes 225 Earth days to complete one orbit around the Sun.
    • Day length: A day on Venus (one full rotation on its axis) is incredibly long—243 Earth days—and even stranger, it rotates backward compared to most planets. This means that on Venus, the Sun rises in the west and sets in the east.
    • Day vs Year: A day on Venus is longer than a year, as it takes less time to complete an orbit around the Sun than it does to rotate once on its axis.

 

1. 3. Surface and Temperature

• • • The surface of Venus is covered in vast plains, mountains, and thousands of volcanoes. Although no active volcanism has been directly observed, there are signs that the planet may still be volcanically active.
    • Temperature: Venus is the hottest planet in the Solar System, with surface temperatures reaching around 465°C (870°F), even hotter than Mercury, despite being farther from the Sun. This extreme heat is due to its runaway greenhouse effect, where thick clouds of carbon dioxide trap heat.

 

1. 4. Atmosphere

• • • Venus has an extremely dense atmosphere, composed mostly of carbon dioxide (96.5%) with clouds of sulfuric acid. The pressure at the surface is about 92 times that of Earth’s, equivalent to being nearly 1 km (0.6 miles) underwater.
    • The thick atmosphere causes a constant cloud cover, which reflects sunlight and makes Venus one of the brightest objects in the sky, often visible just after sunset or before sunrise, earning it the nickname the “Evening Star” or “Morning Star”.

 

1. 5. Magnetic Field

Venus has a very weak and almost non-existent magnetic field, possibly due to its slow rotation and lack of internal convection processes in its core.

 

1. 6. Exploration

• • • Venus has been the subject of many spacecraft missions, mainly from the former Soviet Union, which landed the Venera probes on its surface in the 1960s and 70s. NASA’s Magellan orbited Venus in the early 1990s and mapped much of its surface using radar.
    • Future missions, such as NASA’s VERITAS and DAVINCI missions, aim to further explore Venus’s surface and atmosphere.

 

1. 7. Greenhouse Effect

Venus provides a dramatic example of a runaway greenhouse effect, where the thick CO₂ atmosphere traps solar heat, leading to a surface hot enough to melt lead. This has made Venus an important study subject for understanding climate change on Earth.