Venus

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 it to be a paradise. In fact, Venus is actually the most hostile of the inner planets for humans to visit, due to its incredibly toxic atmosphere. Despite its danger, Venus is still fascinating.

First of all, Venus’s atmosphere is very thick—at over 70 km—and is 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 of around 462°C. This temperature is hot enough to melt lead, and is maintained day and night due to the dense atmosphere.

This thick, dense atmosphere also creates intense pressure on Venus’ surface, almost 92 times that on 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 then be quixkly flattened!

Venus' 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 much larger than those on Earth.

While Mercury might be famous for its short years and 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 (a mere 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 roughly a slow jogging speed.

The oddest thing about Venus is that it rotates in the opposite direction to all the other planets, spinning in a clockwise direction - which we call retrograde rotation. No one knows for sure why this it, but its possible Venus took a big bump in its early life, or the influence of the Sun, or its thick atmosphere (or a combination of these effects) caused its spin to reverse direction.

Crazy, super long days

Exploring Venus

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

So, what we do 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 lasted only for a few minutes or hours. Venera 7 was the first to send back data from Venus (temperature, pressure and wind speed), and Venera 9 the first to send pictures of the Venetian surface before it succumbed to the atmosphere.

Recent missions like Venus Express and future missions will map the surface of Venus in more detail, and study its atmosphere to learn more about the geology and the greenhouse effect which drives the extreme climate.

One thing that we may find on Venus is life. While unlikely, recent studies have detected phosphine in the upper atmosphere of Venus, which is normally associated with biological life, at least on Earth. There are many chemical reactions we do not know of, simply because we have no similar environments on Earth to those on Venus. This means that phosphine could be a product of, for now, unknown processes that are abiotic (in other words, not from life). So who knows!

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How to see Venus

Venus is one of the brightest objects in the night sky and can be easily seen with the naked eye from Earth. 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.