Planet Venus

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Image of the planet taken by the Pioneer Venus Orbiter in 1979.

Magellan radar image of the Venusian volcano Maat Mons.

• Venus is the second planet from the sun and very similar in size to the Earth, its diameter is only 400 miles (644 km) smaller than Earth.
• At its closest point to Earth the planet is a mere 24 million miles away (38 million km).
• It orbits the sun at an average distance of 67 million miles (108 million km).
• The planet orbits around the sun every 225 days but rotates on its own axis slower than any other planet, taking 243 days compared to 24 hours on Earth. Meaning a day on Venus is longer than its year! It also rotates in the opposite direction of the other planets.
• It is surrounded by extremely thick cloud making it impossible to see the surface from orbit without radar or radio equipment.
• The force of gravity is only 12% less than we have on Earth but the extreme weight of atmospheric pressure would crush a human.
• Apart from the moon Venus is the brightest object in the night sky.
• It was the first planet to be observed by a passing spacecraft.

The great thing about Venus is that it’s always easy to find, it’s the brightest "star" to rise just as the sun is setting, it's so bright it’s impossible to miss. As Venus is an inner planet it goes through phases just like the moon, from full to a thin crescent. Counter intuitively Venus is actually much brighter when it’s a thin crescent, this is because at this point it's much closer to Earth.

As Venus is so close and bright you don’t need a super duper telescope to view it, even if you had a more expensive telescope there isn’t actually a lot of detail to make out. This is because Venus is covered in very thick cloud so viewing any surface markings is impossible, although you may be able to make out some cloud detail. Even so it’s still a thrill to observe our closest neighbor and watch it go through its different phases.

Below are a couple of recommended low cost scopes that are perfectly adequate for observing Venus. The Orion Skyscanner is incredibly easy to set up and you could be checking out Venus within minutes of taking it out the box. It has a good enough aperture to capture dark and light areas in the planet’s clouds. The Meade 20218 NG-70SM comes with a sturdy tripod and is a very good entry level telescope. It’s great value for money at only around $75 and will provide you with very reasonable views of Venus.

Venus is often referred to as Earth’s sister planet or even twin. This is mainly due to the fact that it is very similar in size to our own planet. As it turns out we share other similarities, the mass, density and gravity of Venus are all very similar to Earths. Indeed studies have shown that a few billions years ago it had liquid water flowing over its surface and may well have harbored primitive lifeforms. Unfortunately for the planet there are also fundamental differences which means that while Earth is a hospitable world teeming with life, Venus is a choked, oven baked desert.

The atmospheres of both worlds are very different, Earth’s is thin and nitrogen based whereas the atmosphere on Venus is extremely thick and composed almost entirely of carbon dioxide. Ninety percent of Earth’s atmosphere is within just 6 miles (10 km) of its surface, on Venus it would be 30 miles (50 km) from its surface before reaching 90% of its atmosphere. As a result of having the heaviest atmosphere of any planet in the solar system atmospheric pressure on Venus is a massive 90 times stronger than on Earth, the equivalent of being more than a kilometer under the ocean, a human being would be crushed in these conditions. Perhaps the biggest difference is the intense heat, surface temperatures can reach an incredible 465C (870F) which is hot enough to melt lead.

So where did it all go wrong for our twin planet? Well unfortunately it was just too close to the sun. The water it once had flowing across its surface quickly evaporated and without the cleansing effect of rain huge amounts of carbon dioxide built up in its atmosphere from intense volcanic activity. This created a runaway greenhouse effect, our twin reached the point of no return ending up with the hottest surface temperature of any planet in the solar system.

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Images & Video

Surface of Venus (Venera 13) 1981

Radar images of the Venusian surface

Venus under the clouds

Future and Past Missions to Venus