VENUS

       Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has no natural satellite. After the Moon, it is the brightest natural object in the night sky. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°.

       Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). However, it has also been shown to be radically different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet's surface is 92 times that of Earth's. With a mean surface temperature of 462 °C (863 °F), Venus is by far the hottest planet in the Solar System. Venus may have possessed oceans in the past, but these would have vaporized as the temperature rose.

       Venus is one of the four terrestrial planets in the Solar System, meaning that, like Earth, it is a rocky body. In size and mass, it is similar to Earth, and is often described as Earth's "sister" or "twin". The diameter of Venus is 12,092 km (only 650 km less than Earth's) and its mass is 81.5% of Earth's.

       The absence of evidence of lava flow accompanying any of the visible caldera remains an enigma. The planet has few impact craters, demonstrating the surface is relatively young, approximately 300–600 million years old. In addition to the impact craters, mountains, and valleys commonly found on rocky planets, Venus has some unique surface features.
       Without seismic data or knowledge of its moment of inertia, little direct information is available about the internal structure and geochemistry of Venus. The similarity in size and density between Venus and Earth suggests they share a similar internal structure: a core, mantle, and crust. Like that of Earth, the Venusian core is at least partially liquid because the two planets have been cooling at about the same rate.

        Venus has an extremely dense atmosphere, which consists mainly of carbon dioxide and a small amount of nitrogen. The atmospheric mass is 93 times that of Earth's atmosphere, whereas the pressure at the planet's surface is about 92 times that at Earth's surface—a pressure equivalent to that at a depth of nearly 1 kilometer under Earth's oceans.

        Venus is always brighter than any star (apart from the Sun). The greatest luminosity occurs during crescent phase when it is near Earth. The planet is bright enough to be seen in a mid-day clear sky, and it can be easy to see when the Sun is low on the horizon. As an inferior planet, it always lies within about 47° of the Sun.