Venus, "the jewel of the sky", was once know by ancient human astronomers as the morning star and evening star, and was later referred to as Earth's sister planet. Both are similar in size, mass, density and volume. Both formed about the same time and condensed out of the same nebula. However, this is where the similarities end.
Equatorial diameter: 12104 km
Reciprocal mass, Sol: 1:408524
Surface gravity: 0.9030 G
Escape velocity: 10.360 km/s
Semimajor axis: 0.723301 au
Orbital inclination: 3°23'41"
Longitude of the ascending node: 76°39'35"
Argument of pericentre: 54°50'38"
Mean anomaly: 41°45'55"
Osculating period: 224.68667 days
Mean orbital period: 224.701 days
Mean synodic period: 1.599 days
Mean axial rotation period: 243.160 days
Mean axial inclination: 22°51'
A Venusian day is 243 standard days and is longer than its year of 225 days. Oddly, Venus rotates from east to west. To an observer on Venus, the sun would rise in the west and set in the east.
Mean max temperature: 40 C
Mean min temperature: -33 C
- Carbon dioxide, 0.96%
- Nitrogen, 75+%
- Oxygen 22.55%
- Trace amounts of: Sulfur dioxide, water vapor, carbon monoxide, argon, helium, neon, hydrogen chloride, and hydrogen fluoride.
Originally, Venus was scorched with a surface temperature of about 482°C. This high temperature was primarily due to a runaway greenhouse effect caused by the heavy atmosphere of carbon dioxide. Sunlight passed through the atmosphere to heat the surface of the planet. Heat was radiated out, but was trapped by the dense atmosphere and not allowed to escape into space. This made Venus hotter than Mercury.
Thanks to modern terraforming techniques, however, currently Venus is considered a pleasant place to live and no longer has any dramatic temperatures or weather conditions nor high air pressure.
Venus' surface is relatively young geologically speaking. It appears to have been completely resurfaced 300 to 500 million years ago. The Venusian topography consists of vast plains covered by lava flows and mountain or highland regions deformed by geological activity.
Maxwell Montes in Ishtar Terra is the highest peak on Venus. The Aphrodite Terra highlands extend almost half way around the equator. Liquid water does not exist on the surface and cannot account for the bright highlands; one theory suggests that the bright material might be composed of metallic compounds. Studies have shown the material might be iron pyrite. It is unstable on the plains but would be stable in the highlands. The material could also be some type of exotic material which would give the same results but at lower concentrations.
Venus was scarred by numerous impact craters distrubuted randomly over its surface. Small craters less that 2 kilometers (1.2 miles) were almost non-existent due to the heavy Venusian atmosphere. The exception occurs when large meteorites shatter just before impact, creating crater clusters. Volcanoes and volcanic features were even more numerous; at least 85% of the Venusian surface was covered with volcanic rock. Huge lava flows, extending for hundreds of kilometers, have flooded the lowlands creating vast plains. More than 100,000 small shield volcanoes dotted the surface along with hundreds of larger volcanos. Flows from volcanos produced long sinuous channels extending for hundreds of kilometers, with one extending nearly 7,000 kilometers (4,300 miles).
Giant calderas more than 100 kilometers (62 miles) in diameter are found on Venus. Several features unique to Venus include coronae and arachnoids. Coronae are large circular to oval features, encircled with cliffs and are hundreds of kilometers across. They are thought to be the surface expression of mantle upwelling. Archnoids are circular to elongated features similar to coronae. They may have been caused by molten rock seeping into surface fractures and producing systems of radiating dikes and fractures.