Venus the meaning in Latin is youthful. This planet was named after the Roman Goddess of love and beauty. Venus is the second planet from the Sun and the sixth largest. Venus’ orbit is the most nearly circular of that of any planet, with an eccentricity of less than 1%.
Venus has been known since prehistoric times. It is the brightest object in the sky except for the Sun and the Moon. Since Venus is an inferior planet, it shows phases when viewed with a telescope from the perspective of Earth. Galileo’s observation of this phenomenon was important evidence in favor of Copernicus’s heliocentric theory of the solar system.
The first spacecraft to visit Venus was Mariner 2 in 1962. It was subsequently visited by many others (more than 20 in all so far), including Pioneer Venus and the Soviet Venera 7 the first spacecraft to land on another planet, and Venera 9 which returned the first photographs of the surface. The first orbiter, the US spacecraft Magellan produced detailed maps of Venus’ surface using radar. ESA’s Venus Express is now in orbit with a large variety of instruments.
Venus is one of the four solar terrestrial planets, meaning that, like the Earth, it is a rocky body. In size and mass, it is similar to the Earth, and is often described as Earth’s “sister” or “twin”. The diameter of Venus is 12,092 km (only 650 km less than the Earth’s) and its mass is 81.5% of the Earth’s.
Conditions on the Venusian surface differ radically from those on Earth, owing to its dense carbon dioxide atmosphere. The mass of the atmosphere of Venus is 96.5% carbon dioxide, with most of the remaining 3.5% being nitrogen.
In 1967, Venera-4 found the Venusian magnetic field is much weaker than that of Earth. This magnetic field is induced by an interaction between the ionosphere and the solar wind, rather than by an internal dynamo in the core like the one inside the Earth. Venus’s small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation. This radiation may result in cloud-to-cloud lightning discharges.
Little more was discovered about Venus until the 20th century. Its almost featureless disc gave no hint what its surface might be like, and it was only with the development of spectroscopic, radar and ultraviolet observations that more of its secrets were revealed. The first UV observations were carried out in the 1920s, when Frank E. Ross found that UV photographs revealed considerable detail that was absent in visible and infrared radiation. He suggested this was due to a very dense, yellow lower atmosphere with high cirrus clouds above it.
Radar observations in the 1970s revealed details of the Venusian surface for the first time. Pulses of radio waves were beamed at the planet using the 300-m radio telescope at Arecibo Observatory, and the echoes revealed two highly reflective regions, designated the Alpha and Beta regions.
The observations also revealed a bright region attributed to mountains, which was called Maxwell Montes. These three features are now the only ones on Venus that do not have female names.
Venus is usually visible with the unaided eye. Sometimes (inaccurately) referred to as the “morning star” or the “evening star”, it is by far the brightest “star” in the sky. There are several Web sites that show the current position of Venus (and the other planets) in the sky. More detailed and customized charts can be created with a planetarium program.
On June 8 2004, Venus passed directly between the Earth and the Sun, appearing as a large black dot travelling across the Sun’s disk. This event is known as a “transit of Venus” and is very rare: the last one was in 1882, the next one is in 2012 but after than you’ll have to wait until 2117. While no longer of great scientific importance as it was in the past, this event was the impetus for a major journey for many amateur astronomers.