Venus

Venus is the second planet from the Sun and the third smallest in our solar system . The planet is named after Venus , the Roman goddess of love, beauty and fertility. The Italian physicist Galileo Galileo observed the planet in the early 1600 s, and discovered that it had phases like the moon. This was among the first observations that clearly contradicted Ptolemy ' geocentric model that placed the earth at the center of the universe , and let the sun and the other planets revolve around the earth.

After the Moon , Venus is the brightest natural object in the night sky and it is bright enough to cast shadows. Since Venus is a planet in the present in relation to the earth, it seems never to be far away from the sun. If you are far enough north (for example, Tromse) on earth is Venus in certain periods circumpolar and visible all night. The same is the case in certain other periods if you are far enough south on earth. It is called the evening star when it is visible after sunset and morning star when it is visible before sunrise.

Venus is classified as a terrestrial planet and is sometimes called Earth's "sister planet" because of the relatively similar size, gravity and composition. The planet is covered by an opaque layer of highly reflective clouds of sulfuric acid to prevent the surface can be seen in visible light from space. Venus has the densest atmosphere of all the terrestrial planets in the solar system, consisting mostly of carbon dioxide . Venus has no carbon cycle that keeps carbon left in rocks and other surface features, and it does not appear that there are any organic life to absorb the carbon in biomass. The surface is a dusty dry desert landscape with many plate-like stones that are periodically refreshed by volcanism .

Early it was speculated much about the surface, but in the 1900 s revealed planetology some of the secrets, and in 1990-1991 charted Magellan project surface in detail. The reason is showing signs of extensive volcanism, and the sulfur in the atmosphere may indicate relatively recent eruptions. The lack of evidence of lava flows associated with the visible caldera remains an enigma. The planet has few impact craters , which shows that the surface is relatively young - ca. 300-600 million years old. There is no evidence of plate tectonics . This may be due to strong faults and that the mantle has a high viscosity . This difference between earth and Venus can be explained by the absence of water. Radioactivity create more heat in Venusian inner than that emitted at the surface.This heat may be released during periods when the surface is undergoing massive transformation.