Venus

Venus is the second planet from the sun and passes closer to the Earth than any other planet at a minimum distance of 108 million km. It can reach magnitudes of -4.7, which is much brighter than the next planet, Jupiter. This is because of its dense atmosphere, which reflect about 65% of the light hitting them.

Venus is the Roman god of love and beauty.

Venus' orbit is the least eccentric of all the planets, but unnusually, the planet itself spins slowly and in reverse compared with the other planets. A Venusian day is 243 Earth days, whilst a year is 225 days.

Venus has no moons.

Semimajor axis (km) 108.21x106 Perihelion (km) 107.48x106 Aphelion (km) 108.94x106 Mean orbital speed (km s-1) 35.02 Sidereal orbit period (days) 224.701 Tropical orbit period (days) 224.695 Synodic period (days) 583.92 Length of day (hours) 2802 Sidereal rotation period (hours) -5832.5 Obliquity to orbit (deg) 177.36

Semimajor axis (AU) 0.72333199 Eccentricity 0.00677323 Inclination (deg) 3.39471 Longitude of ascending node (deg) 76.68069 Longitude of perihelion (deg) 131.53298 Mean longitude (deg) 181.97973 Discoverer Unknown Date of Discovery Classical J2000 Data from NSSDC

Venus has been visited on several occasions by unmanned probes, first in 1962 by Mariner 2, then Mariner 10 (1974) in a flyby to Mercury and later by Pioneer Venus (1978) and also the USSR's landers Venera 7 in 1970 and Venera 9 in 1975. Most recently, Magellan (launched 1989) mapped 98% of Venus' surface.

Venus is very similar to the earth in both size (650km less) and mass and it is probable that it's core is similar too. It seems to have many small volcanoes to relieve the stress of the magma beneath the crust rather than just at the plate boundaries as on the Earth. Magellan data on Venus' gravitational field suggests the planet has a thicker crust than was previously thought.

The clouds of Venus rotate once every four days in a retrograde direction as a result of strong winds. They are composed largely of (80% concentration) sulphuric acid. The surface is sprayed with acid rain as a result. It was only possible to detect the length of the Venusian day by radar as the clouds entirely engulf the surface.

Only in the 1950s, by the planet's radio emissions, did astronomers get any clue as too the surface conditions. It turned out that Venus is hot, hotter than boiling water, which was confirmed when the USSR's Venera 4 was destroyed due to the temperature and pressure. Surface temperature was found to be about 750K and the pressure 90 times that of Earth. This is because of the greenhouse effect, the sunlight reaching the surface is absorbed and reemitted by the planet, only to be absorbed like a blanket by the carbon dioxide atmosphere and sulphuric acid clouds.

There are several continental areas, notably Ishtar Terra, the size of the USA and the largest of all; Aphrodite Terra. There is a large mountain range, Maxwell Montes, reaching 12km above the surroundings in Ishtar Terra, while Aphrodite Terra has a vast system of valleys spanning thousands of kilometres.

Mass (kg)	4.8685x1024
Equatorial radius (km)	6051.8
Polar radius (km)	6051.8
Mean density (kg m-3)	5243
Equatorial surface gravity (m s-2)	8.87
Escape Velocity (km s-1)	10.36
Black-body temp (K)	231.7
Solar intensity (W m2)	2613.9
Natural satellites	0