Hot and Heavy

Venus is the second planet from the Sun and is often called Earth's "sister planet" because of its similar size and composition. Venus is named after the Roman goddess of love and beauty, so you would expect a paradise. However, Venus is the most hostile of the inner planets for humans to visit due to its incredibly toxic atmosphere. Despite its danger, it is also fascinating.

First, Venus’s atmosphere is very thick, at over 70 km, and composed mainly of carbon dioxide, with clouds of sulfuric acid. This thick atmosphere creates a strong greenhouse effect, trapping heat and making Venus the hottest planet in the solar system, with surface temperatures around 462°C. This temperature is hot enough to melt lead and is maintained day and night due to the dense atmosphere.

The thick, dense atmosphere also creates intense pressure on Venus’ surface, 92 times that of Earth. Incredibly, this is equivalent to the pressure found 900 metres underwater on Earth. So, if you survived the descent through 70km of acidic clouds, you would melt, burn, dissolve, and be flattened quickly.

This intense atmosphere is driven by volcanic activity, the signs of which litter the Venetian surface. The surface of Venus is relatively young, geologically speaking, with evidence of widespread volcanic activity. This suggests that Venus might still be geologically active today. The surface is also covered with mountains, valleys, and thousands of volcanoes, some of which are larger than those on Earth.

While Mercury might be famous for its short years but long days, on Venus, a day is even longer. It has the longest day of any planet in the solar system at 243 Earth days. Like Mercury, a day on Venus is longer than its year (225 Earth days), but because Venus is so much bigger than Mercury, its spin rate is incredibly slow at a paltry 4 mph (6.5 km/h), or about a slow jogging speed.

The oddest thing about Venus is that it rotates in the opposite direction to all the other planets (Retrograde rotation), spinning in a clockwise direction. No one knows for sure why but its possible Venus took a big bump in its early life or the influence of the sun or its thick atmosphere caused its spin to reverse.

Crazy, Super Long Days

Exploring Venus

This fierce and opaque atmosphere makes exploration of Venus hard, even though its typically the brightest of the planets. Venus is the brightest planet in the night sky due to its highly reflective clouds that reflect about 70% of the sunlight.

So what we know about Venus and its surface is based on missions like Magellan, launched by NASA in 1989. The Magellan spacecraft used radar to map 98% of Venus' surface in high detail, revealing the planet's topography from the relative safety of space. Very few probes have landed on the Venetian surface, and those that did only lasted for a few minutes or hours. Venera 7 was the first to send back pictures of the Venetian surface before it succumbed to the atmosphere.

Recent missions like Venus express and future missions will map the surface in more detail and study its atmosphere to learn more about the geology and the greenhouse effect that drives the extreme climate. One thing that we may find is life. While unlikely, recent studies detected phosphene in the upper atmosphere of Venus which is only normally associated with biological life. So who knows.

Key Stats

How to See Venus from Earth

Venus is one of the brightest objects in the night sky and can be easily seen with the naked eye. It is often called the "Evening Star" or "Morning Star" because it is visible just after sunset or just before sunrise.

• Naked Eye: Venus appears as a very bright, white point of light. It is brighter than any star and is usually the first "star" visible after sunset or the last "star" visible before sunrise.

• Binoculars: Using binoculars, you can see Venus as a bright disc. During its phases, similar to the Moon, you can observe the changing shape of Venus as it orbits the Sun.

• Small Telescope: A small telescope will allow you to see the phases of Venus more clearly. You can observe Venus changing from a small, full disc to a larger, crescent shape as it moves in its orbit around the Sun.