Friday, January 27, 2006

Venuses orbit

Although all planets' orbits are elliptical, Venuses orbit is the closest to circular, with an eccentricity of less than 1%.

As Venus is closer to the Sun than the Earth, it always appears in roughly the same direction from Earth as the Sun (the greatest elongation is 47.8°), so on Earth it can usually only be seen a few hours before sunrise or a few hours after sunset. However, when at its brightest, Venus may be seen during the daytime, making it one of only two heavenly bodies that can be seen both day and night (the other being the Moon). It is sometimes referred to as the "Morning Star" or the "Evening Star", and when it is visible in dark skies it is by far the brightest star-like object in the sky.

The cycle between one maximum elongation and the next lasts 584 days. After these 584 days Venus is visible in a position 72 degrees away from the previous one. Since 5 * 584 = 2920, which is equivalent to 8 * 365 Venus returns to the same point in the sky every 8 years (minus two leap days). This was known as the Sothis cycle in ancient Egypt, and was familiar to the Maya as well. Another association is with the Moon, because 2920 days equal almost exactly 99 lunations (29.5 * 99 = 2920.5).

At inferior conjunction, Venus can get closer to earth than any other planet--little more than 100 times the Moon's average distance. On December 16th, 1850, Venus reached the lowest distance to earth since 1800, with a value of 0,264138541298281 AU = 39514827 kilometres. This will be the closest approach of Venus to earth until December 16th, 2101 when Venus will reach a distance of 0,26431736 AU = 39541578 kilometres to earth.

Monday, January 23, 2006

Venuses Name

Venus is named after the Roman goddess of love, Venus.

The adjective is Venusian it is commonly used for Venus, but it is etymologically incorrect. The true adjective, coming from Latin, Venereal, is avoided because of its modern association with sexually transmitted diseases. Some astronomers use Cytherean, which comes from Cythera. Other less common adjectives include Venerean, Venerian, and Veneran.

The Chinese, Korean, Japanese and Vietnamese cultures refer to the planet as the metal star, 金星, based on the Five Elements.

Friday, January 20, 2006

Earlier Views of Venus

In earlier times, there was considerable speculation concerning the possibility of life on Venus, sometimes with rather elaborate characteristics. In 1686 a French "man of letters", Bernard de Fontenelle, wrote that


I can tell from here . . . what the inhabitants of Venus are like; they resemble the Moors of Granada; a small black people, burned by the sun, full of wit and fire, always in love, writing verse, fond of music, arranging festivals, dances, and tournaments every day. (As Quoted in National Geographic, June, 1975)


Now apart from the fact that this description is rather unremarkable because it sounds like an everyday student life around a great University , it turns out that monsieur de Fontenelle was quite incorrect about Venus and its conjectured inhabitants.