Diameter: 7,520 miles (12,100 km)
Mean distance from Sun: 67,200,000 miles (108,200,000 km)
Orbital period (year): 225 Earth days
Rotation period (day): 243 Earth days
Atmosphere: 96.5% carbon dioxide, 3.5% nitrogen, traces of sulfur dioxide, water vapor, argon, carbon monoxide and helium
Venus is sometimes called “Earth's twin.”
Earth and Venus are about the same size, but Venus is a bit smaller and less dense than Earth. The gravitational pull on Venus is also less, so someone weighing 100 pounds on Earth would weigh only 91 pounds on Venus. However, the air pressure is 92 times greater than on Earth, so instead of feeling lighter, you would be squashed.
Venus is more often mistaken for a UFO than any other astronomical object.
Venus is amazingly bright and can easily be mistaken for an aircraft coming towards you. Venus is often the brightest object in the sky except for the Moon. This is because besides being the nearest planet to us, Venus is surrounded by a highly reflective white cloud layer. At its very brightest you can see it during the day.
Like the Moon, Venus has phases.
Venus shines by reflected sunlight, as the Moon does. It also seems to change shape and size as it orbits the Sun. You can see these changes through a telescope or good binoculars. This diagram from the University of Michigan astronomy site shows the phases. You can see that although a full moon is very bright, the full Venus isn't nearly as bright as a crescent Venus.
Venus has been known as both the “morning star” and the “evening star.”
Ancient astronomers once thought that Venus was two different objects. Later on they realized that it was actually a planet and there was only one. When it's moving towards us in its orbit, we can see it in the evening and when it's moving away from us, we see it in the morning.
Venus was the Roman goddess of love and beauty, but the planet has also represented war.
We know this beautiful planet as the goddess of love, but in the Mayan and other civilizations of Central America, a decision to go to war was strongly influenced by the position of Venus in the sky. And the Babylonians associated the planet Venus with Ishtar who was their goddess of both love and war. (Babylonia was an ancient civilization in the Middle East.)
Venus spins backwards.
Astronomers say that its rotation is retrograde. That means that Venus spins on its axis in the opposite direction to which Venus and all the other planets go around the Sun. It also means that if you were on Venus you'd see the Sun rise in the west and set in the east. Or you would if you could see the Sun – remember the thick clouds.
Most of the features on Venus have been named after women.
The mountains and craters and other features are named for goddesses and mythological figures, writers and scientists and other prominent women.
Venus is the hottest planet in the Solar system, even though it's not the closest to the Sun
Mercury is the nearest planet to the Sun, but Venus has its cloud cover and carbon dioxide atmosphere to keep the heat in. The surface temperature is about 465 degrees Celsius (870 degrees Fahrenheit). This is hot enough to melt lead. There wouldn't be any iced water to cool you down either – Venus is a very dry world.
A day on Venus is nearly four months long.
Venus takes 225 Earth days to orbit the Sun and 243 Earth days to rotate once on its axis. It looks as though a day on Venus is longer than a year! But Earth turns on its axis in the same direction as it orbits the Sun, and Venus doesn't. Venus goes around the Sun in the same direction as Earth does, but it rotates in the opposite direction. If you could see the Sun rising and setting from Venus, it would rise in the west and set in the east. One full day would be 117 Earth days long.
NASA Magellan Guide, http://www2.jpl.nasa.gov/magellan/guide8.