Venus is the second planet from the Sun and is the sixth largest. It is the brightest object in the night sky except for the Moon. Venus orbits the Sun once every 224.7 Earth days and gets as close to the Sun as 107.476 million kilometers and as far away from the Sun as 108.942 million kilometers. This makes the orbit of Venus less elliptical and more circular than any other planets. The temperature on the surface of Venus can reach as high as 740 degrees Kelvin. This is due to a phenomenon called the greenhouse effect whereby carbon dioxide in the atmosphere of Venus traps the Suns heat inside. This makes Venus the hottest planet in the Solar System. Venus is even hotter than Mercury despite being farther away from the Sun.
Venus is 12,100 kilometers in diameter and has a mass of 4.869e+24 kilograms. This makes Venus similar to the Earth and has often been called Earths sister planet. But the similarities end there. One major difference between the Earth and Venus is that Venus rotates on its axis from east to west, which means if you lived on Venus you would see the Sun rise in the west and set in the east. The atmosphere on Venus is mostly carbon dioxide choked with sulfuric acid and has a pressure at the surface more than 92 times the pressure at sea level on Earth. Unlike the Earth, Venus does not have a magnetic field generated by its iron core. This may be the result of how slowly Venus rotates on its axis. The only magnetic field Venus has is very weak and is produced by the interaction of the solar wind and the ionosphere of Venus.
The surface of Venus is difficult to see through the thick, dense clouds and the first crude images of the surface were obtained using ground based radar. More detailed images were obtained by the Magellan spacecraft which was launched to Venus on May 4, 1989 and spent four and a half years radar mapping 98 percent of the surface of Venus. Later, the European Space Agency launched the Venus Express on November 9, 2005 and on April 11, 2006 it slipped into a polar orbit around Venus. These probes have now provided us with an accurate map of Venus.
Most of the surface of Venus is relatively flat plains created by giant pools of lava. Venus has thousands of small volcanoes and hundreds of large volcanoes many of which are over 100 kilometers in diameter. There are fairly large craters scattered at random all over the surface of Venus. These craters are more than 2 kilometers wide and smaller craters do not exist because smaller meteors burn up in the thick atmosphere of Venus. The map of Venus is dominated by two large highland areas, the Ishtar Terra, where the Maxwell Montes, the highest mountain can be found and the Aphrodite Terra highlands.
More missions to Venus are planned for the future and NASAs MESSENGER spacecraft just completed two flybys of Venus in October 2006 and June 2007 while on its way to Mercury. A spacecraft called BepiColombo, which was launched by the European Space Agency, will also perform two flybys of Venus on its way to Mercury. Japan is planning to launch the Planet-C Venus climate orbiter in 2010 and NASA has proposed a spacecraft called VISE the Venus In-Situ Explorer which will actually land on Venus. Once on the surface the Venus In-Situ Explorer will take a core sample and examine it. These mission to Venus will tell us more about the chemical composition and climate on Earths sister planet.