Wikijunior:Solar System/Venus

Venus Facts: Venus is the second closest planet to the Sun. It is a terrestrial planet. This means that we think it was created in a similar way to our planet Earth and is made of rock.
 * Venera 7, the first space probe to land on Venus, was destroyed by the hostile conditions on Venus after only 23 minutes.
 * Almost all of the surface features on Venus are named after women.
 * A day on Venus is equal to 117 days on Earth.
 * It has been proposed that some microbes could live in Venus's clouds.

How big is Venus?
Venus is only slightly smaller than the Earth. This is one reason why Venus is sometimes thought of as Earth's "twin". Venus has a diameter of about 12,100 km. It has also been visited by many probes.

What is the surface like on this planet?
The surface of Venus is very different from the surface of the Earth. It is very dry and hot enough to melt lead. The pressure on the surface is very high. It is the same pressure as being 1 km (3,280 feet) below the surface of the sea on Earth.

Channels that look like rivers have formed on Venus. Scientists think these channels are formed from erupting lava. The lava flows along as it cools down, creating the channels. One feature only Venus seems to have is unusual volcanoes called arachnoids. These are volcanoes that have formed differently from other volcanoes we have found in the Solar System. We don't know exactly how they were formed. Venus also has volcanoes like those on Earth.

Parts of the surface of Venus look something like continents. The largest of these areas is called Ishtar Terra (land of Ishtar, from the Babylonian goddess who was similar to Venus). Deep basins like those under the Earth's oceans have also been discovered. On Venus, though, they have no water. Features like mountain ranges and meteor craters have also been found on Venus. One of the highest mountains on Venus, Maxwell Montes, is about 11 km taller than Mount Everest, the highest mountain on Earth.

On the night side of the planet, there is a strange effect called Ashen Light. For some reason, the dark side of Venus has a subtle glow. There are various theories about this. One of the earliest theories &mdash; now disproved, of course &mdash; was that there were aliens on Venus and they were celebrating a new Venusian emperor. Currently, one of the more believed ones is this: There is a high concentration of carbon dioxide. When it is hit by the ultraviolet rays of the sun, they change into carbon monoxide and oxygen, and emit green light. The entire chemical procedure is CO2 → CO + O.



How long is a day on Venus?
Venus rotates (spins around) even more slowly than Mercury. One full rotation of Venus takes about 243 Earth days. Venus also rotates in the opposite direction to most of the other planets in the Solar System. One day on Venus, from noon to noon, depends on the length of the year as well as the rotation time, and is about 117 earth days.

How long is a year on Venus?
One year on Venus is almost 225 Earth days long. This is less time than it takes Venus to rotate on its axis and less than two Venus days.

What is Venus made of?
The surface of Venus, its crust, is covered in nothing but rock. But, the core of Venus is made of nickel-iron. The atmosphere around Venus is very thick and is made of carbon dioxide, nitrogen, and poisonous gasses that create high pressure and trap in heat.

How much would Venus's gravity pull on me?
If you were on Venus, it would pull you down almost as strongly as Earth. The atmosphere exerts a pressure at the surface more than 90 times Earth's normal sea-level pressure.

Who discovered Venus?
Because Venus is closer to the sun than we are on Earth, we always see it close to the sun in the sky. So it only appears for us just before sunrise in the eastern sky, or just after sunset in the western sky. Many cultures thought Venus in the morning and Venus in the evening were two separate things. The ancient Romans called the evening object Venus (after the goddess of love) and the morning object Lucifer (which means light bearer &mdash; a servant who walked ahead of the sun's chariot with a torch, to light the way). Nobody knows who first thought the two were a single object. The first known written description of them as one object was the Venus Tablet of Ammisaduqa, from about three and a half thousand years ago &mdash; 1581 BCE.

About three thousand years later, in 1610, Italian astronomer Galileo Galilei used a telescope to observe that Venus has phases, just as the moon does. Phases happen because only the side of Venus (or of the Moon) facing the Sun is lighted. The phases of Venus supported the theory of Copernicus that the planets go around the Sun. Then, a few years later in 1639, an English astronomer named Jeremiah Horrocks observed a transit of Venus. That's what it's called when Venus passes right between the Earth and the Sun, so that Venus is visible from Earth during the day as a tiny dot passing across the Sun. In 1761 a Russian astronomer, Mikhail Lomonsov, watching another transit of Venus, saw that Venus has an atmosphere.

Not much more was discovered about Venus until the 1920s. Then, a United States astronomer, Frank Ross, observed Venus using ultraviolet light &mdash; the light that causes sunburn &mdash; and for the first time saw the structure of the clouds on Venus.

However, there is only so much that can be learned about Venus by looking at it from Earth. The first successful pictures of Venus by a space probe were taken by Mariner 2 in 1962. Mariner 2 was the first space probe successfully sent to observe another planet. It showed two important things: Venus has practically no magnetic field, and Venus has temperatures of 490 to 590 K &mdash; that's as hot as the inside of a working oven on Earth!

<!-- Mariner 5 measured the power of Venus' weak magnetic field, and Mariner 10 took ultraviolet pictures revealing huge wind speeds. Venera 3 was the first probe to land on Venera, but its communications failed before it reached the surface. However, Venera 4 managed to collect data while floating down to Venus. Venera 4 measured temperature, air pressure, density, and performed eleven chemical experiments analysing the atmosphere, which was found to be 95% carbon dioxide, all before landing on the surface. Unfortunately, before it did land on the surface, its battery ran out, making it useless. Venera 5 and 6 also conducted tests in a similar manner as Venera 4 but they were crushed by the air pressure once they reached 6 km above the surface. The distance from the surface of Earth to the lowest Cirrus clouds is also 6 km. The first successful landing on Venus was by Venera 7 in 1970. The surface temperature was measured to be 455 °C to 475 °C. However, because of the extremely high temperatures on Venus, Venera 7 malfunctioned within 23 minutes of landing. Venera 8 also landed on Venus, and performed additional tests. Venera 9, in 1975 orbited Venus while dropping a ground vehicle on the surface. These two combined produced an enormous wealth of information, including that the clouds of Venus form in 3 different layers of the atmosphere. Venera 10 was a repeat of Venera 9. NASA then sent two Pioneer spacecraft to see for itself. The Pioneer Venus Multiprobe (PVM) was designed to carry 4 probes to Venus and then release the probes, each going separate directions. The Pioneer Venus Orbiter (PVO) orbited Venus. Both the PVM and the PVO conducted multiple experiments and gave information. Venera 11 and 12 flew by Venus and dropped ground vehicles on Venus to collect more information, however, that failed as the colour cameras and soil analysers both malfunctioned. In 1981, Venera 13 landed and took the first colour picture of Venus, and successfully analysed the soil. Venera 13 holds the record among space probes of lasting the longest on Venus, which was 127 minutes. Also in 1981, Venera 14 detected seismic activity on Venus. In 1984, Vega 1 and 2 were launched. Their main purposes were to mainly float in the atmosphere. They took pictures of a third of the planet, along with collecting more data about the atmosphere. The last Soviet Veneras, Venera 15 and 16 took very high resolution pictures of Venus in 1983. In 1990, the US launched a probe called Magellan, named after Ferdinand Magellan who explored the Caribbean islands in the 16th century. Magellan floated in Venus' atmosphere for 4 years before crashing partially vaporising and crashing into the atmosphere. During that time, it mapped 98% of Venus' surface. There were no more missions to Venus until the 21st century, when the European space agency (ESA) launched Venus Express. Venus Express orbited Venus from 2006 to the end of 2012. In the distant future, it is proposed that Venus should slowly begin to be inhabited by humans, but only after Mars has a population like the Earth. -->

Who is this planet named after?
Venus is named after the Roman goddess of love. Sometimes it can be seen shining brightly just before dawn or just after sunset, when it is called the Morning Star or Evening Star. Some people, like the Aztecs and the Greeks, gave Venus two names – one for the morning and one for the evening.

Because Venus and the Earth are the same size, scientists call Venus "Earth's sister planet". For a long time most scientists thought that Venus had plants, animals, and possibly even people. However because Venus is so hot we now know that it is impossible for anything to live there.

How long would it take people to get there?
It could take around a year and a half to get there. But it is very unlikely someone would go to Venus.