Author: Fraser Cain

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Where did the planet Venus come from? What’s the origin of Venus. Actually, Venus and the rest of the planets in the Solar System all formed at the same time, out of the same nebula, about 4.6 billion years ago.

Let’s go back then, 4.6 billion years ago, before there was a Sun or any planets. In this region of space was a large diffuse cloud of cold molecular hydrogen. And then some event, like a supernova explosion, or gravitational disturbance of a passing star caused the cloud to collapse. As it collapsed, it broke up into knots of gas; each of which would eventually go on to form a star.

As the material collapsed down, it began to spin because of the conservation of momentum from all the particles in the cloud. The center of the cloud became denser and denser, eventually becoming our Sun. This was surrounded by a flattened disk of material; and within this disk is where the planets, including Venus formed. It’s believed that all the planets formed together, at the same time within this disk.

Once the Sun had enough temperature and pressure in its core to ignite fusion, it generated powerful solar winds that blasted away all of the leftover material in the Solar System. All that remained were the planets and their moons.

Astronomers know that all of the planets formed at the same time because of meteorites discovered here on Earth. No matter where in the Solar System they originally came from, all of these meteorites were formed at the same time; about 4.6 billion years ago.

So the origin of Venus is the same origin for all the planets in the Solar System. They all formed out of the solar nebula, billions of years ago.

We have written many articles all about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast all about Venus the planet. Listen to it here, Episode 50: Venus.

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What planet gets closest to Venus? It actually depends on where the planets are in their orbits; but you might be surprised to know that Earth is the closest planet to Venus.

What, you were thinking Mercury gets closer to Venus? At their closest point, Mercury and Venus are separated by only 46 million km. Of course, that’s when the two planets are aligned on the same side of the Sun. When they’re on opposite sides of the Sun, Mercury and Venus are 178.7 million km away from each other.

When Earth and Venus are at their closest point, lined up on the same side of the Sun, they’re only separated by 39 million km. But when they’re on opposite sides of the Sun, Earth and Venus are separated by more than 250 million km. So for most of the time, Mercury and Venus are closer to one another.

But the planet that gets closest to Venus is Earth.

And that’s why Venus looks so large and bright from here on Earth. After the Sun and the Moon, Venus is the brightest object in the night sky. It can even shine so brightly that it casts shadows.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

The clouds of Venus are its defining characteristic. We can see the surface of Mars and Mercury, but the surface of Venus is shrouded by thick clouds. For most of history, astronomers had no idea what was beneath those clouds, and they imagined a tropical world with overgrown vegetation and constant rainfall. They couldn’t have been more wrong.

The climate of Venus isn’t tropical at all; it’s hellish. Temperatures on the surface of Venus approach 475 °C, and the atmospheric pressure is 93 times what you experience here on Earth. To experience that kind of pressure, you would need to swim down 1 km beneath the surface of the ocean. Venus’ atmosphere is made almost entirely of carbon dioxide, and not the oxygen/nitrogen mix we have here on Earth.

The clouds we see on Venus are made up of sulfur dioxide and drops of sulfuric acid. They reflect about 75% of the sunlight that falls on them, and are completely opaque. It’s these clouds that block our view to the surface of Venus. Beneath these clouds, only a fraction of sunlight reaches the surface. If you could stand on the surface of Venus, everything would look dimly lit, with a maximum visibility of about 3 km.

The upper cloud deck of Venus is between 60-70 km altitude. This is the part of Venus that we see in telescopes and visible light photographs of the planet.

The clouds on Venus rain sulfuric acid. This rain never reaches the ground, however. The high temperatures evaporate the sulfuric acid drops, causing them to rise up again into the clouds again.

Venus spacecraft have detected lightning on Venus, coming out of the clouds with a similar process to what we have on Earth. The first bursts of lightning were detected by the Soviet Venera probes and later confirmed by ESA’s Venus Express spacecraft.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

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Earth has the Moon, Jupiter has more than 50 moons, even Pluto has 3 moons. So what about Venus? What number of moons does Venus have? Ready for this?

Venus: number of moons: 0.

That’s right, Venus has no moons at all; not even captured asteroids like Mars. Why doesn’t Venus have any moons?

There appears to be evidence that Venus did have moons in the ancient past. That’s because Venus is rotating backwards from the rest of the planets. Seen from above, all of the planets rotate counter-clockwise. From the surface of the planets, the Sun seems to rise in the east, travel across the sky and then set in the west. But on Venus, it’s backwards; the planet is rotating clockwise, so the Sun rises in the west and sets in the east.

Even stranger, a day on Venus lasts 243 days, while a year on Venus is only 224.7 days. In other words, a day on Venus lasts longer than a year on Venus.

This strange rotation is evidence that Venus was probably whacked hard in the past by a planetesimal; a similar event is believed to have happened to the Earth billions of years ago, forming the Moon. It’s possible that this collision threw up material that coalesced into a moon, or even moons. But the material wasn’t high enough in orbit to remain stable around Venus. Instead of orbiting the planet for billions of years, it would have crashed back into the planet. Perhaps the tidal forces from the Sun made the orbit unstable.

Unfortunately the evidence of any past moons of Venus has been completely wiped away. At some point in the last 300-500 millions years ago, the outer crust of Venus was completely resurfaced, removing all trace of impact craters, and ancient volcanism.

So we’ll never truly know the number of moons that Venus had. But today, it has no moons.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

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The bond albedo of Venus is 0.75.

Albedo is a measurement of the reflectivity of an object. A theoretically perfect reflecting object would have an albedo of 1, and reflect 100% of the electromagnetic radiation that falls upon it. While an object that was perfectly black and doesn’t reflect any light would have an albedo of 0. In real life, objects in the Solar System have albedo values between 0 and 1. And in the case of Venus, the albedo is 0.75.

Just for comparison, the bond albedo of the Moon is only 0.12. That’s actually pretty dark. The brightest albedo in the Solar System is Saturn’s moon Enceladus, with an albedo of 0.99. It reflects almost all of the light that falls onto it.

One of the reasons that Venus is so bright in the sky is because of its high albedo. This albedo comes from the permanent cloud layer that surround the planet. These clouds are made up of sulfuric acid that reflect much of the radiation that falls upon them.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

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Seen from Earth, Venus is a featureless ball; even the most powerful Earth-based telescope shows only clouds and more clouds. But those clouds are moving fast. The winds on Venus are powerful, circulating around the planet in just a matter of days. But because of Venus’ high temperatures and intense atmospheric pressure, they don’t behave like the winds on other planets.

The atmosphere of Venus extends up from the surface of the planet, up to an altitude of about 250 km. Down at the surface, the air pressure is 93 times higher than what we experience here on Earth. But once you rise up in altitude, the pressure drops to Earth surface pressure and then even lower.

At the very top of the cloud layers on Venus, wind speeds reach 355 km/hour (or 100 meters/second). This is the same the jet stream here on Earth. As you descend through the cloud layers, though, the wind speeds pick up. In the middle layer, the winds can reach speeds of more than 700 km/hour. That’s faster than the fastest tornado speed ever recorded on Earth.

But then as you descend further down through the clouds, the thickening atmosphere slows the winds down, so that they act more like currents in the ocean than winds in the atmosphere. Down at the surface, the winds only move at a few km/hour. That’s not much, but the thick atmosphere can still kick up dust and push around small rocks.

The winds on Venus travel in a westerly direction, the same backwards direction that Venus rotates. Seen from above, Venus rotates in a clockwise direction. This is backwards from the other 7 planets, which rotate counter-clockwise.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

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Scientists call Venus Earth’s twin planet and for good reason. Our two planets are similar in size, mass, density, gravity, and composition. Of course, they have some enormous differences as well; differences that would kill you instantly if you tried to step foot on Earth’s twin planet. Earth’s evil twin planet, maybe.

Let’s look at the similarities first. For starters, the size of Venus is very close to Earth. The diameter of Venus is 12,103.6 km. That’s only 95% of the Earth’s diameter of 12,756.2 km. If you put the two planets side by side, you’d have a hard time telling which one’s bigger.

The volume of Venus is 85.7% the volume of Earth, and it has 90% of the Earth’s surface area. The mass of Venus is 81.5% the mass of the Earth, and even the force of gravity is only 90% of what you experience here on Earth.

The composition of the two planets is similar too. Both have metal cores surrounded by a mantle of silica rock, and then a thin crust. There are some differences here, though. Earth’s core has convection which generates the planetary magnetic field, while Venus doesn’t have a similar magnetic field. Earth has plate tectonics, which help release heat from within the planet, while Venus doesn’t.

But there are bigger differences. And this is where it’s better to consider Venus as an evil twin planet. The temperature of Venus across the whole planet is 461.85 °C. That’s hot enough to boil lead! Spacecraft from Earth have only lasted a couple of hours at maximum because of the incredible temperatures. In fact, Venus is the hottest planet in the Solar System.

And if the temperature isn’t bad enough, the air pressure is even worse. The atmospheric pressure on the surface of Venus is 93 times higher than what you’d experience on Earth. In fact, you’d have to travel a kilometer beneath the surface of the ocean to experience that kind of pressure. While Earth’s atmosphere is made up of oxygen and nitrogen with trace amounts of carbon dioxide, Venus’ atmosphere is 96.5% carbon dioxide with the rest nitrogen. It has clouds of sulphuric acid that rain down to add to the planet’s lethality.

Earth has vast reserves of water, while Venus is almost completely dry. There are no reserves of water on the surface of Venus, and just a trace amount of water in its atmosphere. Because Venus doesn’t have a global magnetic field, it’s constantly pummeled by the Sun’s solar wind, which strips the lightest elements out of its atmosphere. Satellites have detected a constant stream of hydrogen atoms streaming away from Venus, lost from the planet forever.

And just one last difference, Earth has the Moon, but Venus has no moons. It might have had a moon in the past, but it’s believed to have crashed into the planet a long time ago.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

References:
NASA Solar System Exploration: Venus
NASA Solar System Exploration: Earth

Venus might look like a virtual twin of the Earth in terms of size, but its temperature and atmosphere make it very different from the Earth. The temperatures can reach almost 500°C, and the atmospheric pressure is almost 100 times what you would experience on the surface of Earth. With such a terrible environment, you might be surprised to know that spacecraft have landed on Venus (although, they sure didn’t last long).

The first spacecraft to enter the atmosphere of Venus was the Soviet Venera 3 probe, which crash landed on March 1, 1966. It was destroyed in the upper atmosphere, so it wasn’t able to return any useful information back to Earth.

The next spacecraft to attempt a landing on Venus was the Soviet Venera 4 spacecraft, which entered the atmosphere on October 18, 1967. Venera 4 was able to deploy several science experiments and was operating them as it passed down through Venus’ atmosphere. But mission planners didn’t realize that the atmosphere of Venus was so thick, and so it ran out of battery power about 25 km above the surface of Venus. But this failure helped missions planners better understand conditions on Venus.

The Venera 7 spacecraft was built to handle 180 times Earth atmospheric pressure, and used a special parachute to drop it down quickly through the atmosphere. It’s believed that the parachute partially failed, and so it impacted the surface of Venus hard. It was only able to return temperature data back to Earth for about 20 minutes.

Venera 8 survived for 50 minutes on the surface of Venus, sending back data.

But the first photographs taken from the surface of Venus were sent back by the Venera 9 and 10 spacecraft. Venera 9 landed on the surface of Venus on October 22, 1975 and operated on the surface of Venus for 53 minutes. It sent back the first images ever captured from the surface of Venus. Venera 10 landed on October 25th, and captured images of pancake-shaped lava rocks. Venera 10 lasted for 65 minutes, and was able to see farther into the distance than Venera 9.

But the most successful Venus landings were the Soviet Venera 13 and 14, which touched down on March 1st and March 5th, 1982. They both survived for over an hour, and returned the first color images ever captured from the surface of Venus.

All of the spacecraft that ever landed on Venus are probably still there today.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

If you’d like more information on Venus, check out Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

Reference:
NASA Solar System Exploration: Missions to Venus
NASA: Mission to Venus Timeline
NASA Planetary Science: Mission to Venus