Jumat, 30 Januari 2009

venus

Venus was a major Roman goddess principally associated with love, beauty and fertility, the equivalent of the Greek goddess Aphrodite.

Venus was the consort of Vulcan. She was considered the ancestor of the Roman people by way of its legendary founder, Aeneas, and played a key role in many Roman religious festivals and myths.

Venus in mythology

For more details on this topic, see Aphrodite.

Like most other gods and goddesses in Roman mythology, that of Venus consists of whole-cloth borrowings from the Greek mythology of her equivalent counterpart Aphrodite.

Cult

Her cult began in Ardea and Lavinium, Latium. On August 15, 293 BC, her oldest-known temple was dedicated, and August 18 became a festival called the Vinalia Rustica. On April 25, 215 BC, a temple to Venus was dedicated outside the Colline gate on the Capitol, to commemorate the Roman defeat at the Battle of Lake Trasimene. In some myths, Eros is the son of Venus and Ares, who was the god of war.

Associated deities

Venus was commonly associated with the Greek goddess Aphrodite and the Etruscan deity Turan, borrowing aspects from each.

Additionally, Venus has been compared to other goddesses of love, Tlahuizcalpantecuhtli in Aztec mythology, Kukulcan in Maya mythology, Frigg and Freyja in the Norse mythos, and Ushas in Vedic religion. Ushas is also linked to Venus by a Sanskrit epithet ascribed to her, vanas- ("loveliness; longing, desire"), which is cognate to Venus, suggesting a Proto-Indo-European link via the reconstructed stem *wen- "to desire".[1]

Venus is also associated with the Latvian god Auseklis, whose name derives from the root aus-, meaning "dawn". Auseklis and Mēness, whose name means "moon", are both Dieva dēli ("sons of God").

Epithets

Like other major Roman deities, Venus was ascribed a number of epithets to refer to different aspects or roles of the goddess.

Venus Acidalia was,[ according to Servius, derived from the well Acidalius near Orchomenus, in which Venus used to bathe with the Graces; others con­nect the name with the Greek acides (άκιδες), i.e. cares or troubles.

Venus Cloacina ("Venus the Purifier"), was a fusion of Venus with the Etruscan water goddess Cloacina, likely resulting from a statue of Venus being prominent near the Cloaca Maxima, Rome's sewer system. The statue was erected on the spot where peace was concluded between the Romans and Sabines.

Venus Erycina ("Venus from Eryx"), also called Venus Erucina, originated on Mount Eryx in western Sicily. Temples were erected to her on the Capitoline Hill and outside the Porta Collina. She embodied "impure" love, and was the patron goddess of prostitutes.

Venus Felix ("Lucky Venus") was an epithet used for a temple on the Esquiline Hill and for a temple constructed by Hadrian dedicated to "Venus Felix et Roma Aeterna" ("Favorable Venus and Eternal Rome") on the north side of the Via Sacra. This epithet is also used for a specific sculpture at the Vatican Museums.

Venus Genetrix ("Mother Venus") was Venus in her role as the ancestress of the Roman people, a goddess of motherhood and domesticity. A festival was held in her honor on September 26. As Venus was regarded as the mother of the Julian gens in particular, Julius Caesar dedicated a temple to her in Rome. This name has also attached to an iconological type of statue of Aphrodite/Venus.

Venus Kallipygos ("Venus with the pretty bottom"), a form worshipped at Syracuse.

Venus Libertina ("Venus the Freedwoman") was an epithet of Venus that probably arose from an error, with Romans mistaking lubentina (possibly meaning "pleasurable" or "passionate") for libertina. Possibly related is Venus Libitina, also called Venus Libentina, Venus Libentia, Venus Lubentina, Venus Lubentini and Venus Lubentia, an epithet that probably arose from confusion between Libitina, a funeral goddess, and the aforementioned lubentina, leading to an amalgamation of Libitina and Venus. A temple was dedicated to Venus Libitina on the Esquiline Hill.

Venus Murcia ("Venus of the Myrtle") was an epithet that merged the goddess with the little-known deity Murcia or Murtia. Murcia was associated with the myrtle-tree, but in other sources was called a goddess of sloth and laziness.

Venus Obsequens ("Graceful Venus" or "Indulgent Venus") was an epithet to which a temple was dedicated in the late 3rd century BCE during the Third Samnite War by Quintus Fabius Maximus Gurges. It was built with money fined from women who had been found guilty of adultery. It was the oldest temple of Venus in Rome, and was probably situated at the foot of the Aventine Hill near the Circus Maximus. Its dedication day, August 19, was celebrated in the Vinalia Rustica.

Venus Urania ("Heavenly Venus") was an epithet used as the title of a book by Basilius von Ramdohr, a relief by Pompeo Marchesi, and a painting by Christian Griepenkerl.

On April 1, the Veneralia was celebrated in honor of Venus Verticordia ("Venus the Changer of Hearts"), the protector against vice. A temple to Venus Verticordia was built in Rome in 114 BC, and dedicated April 1, at the instruction of the Sibylline Books to atone for the inchastity of three Vestal Virgins.

Venus Victrix ("Venus the Victorious") was an aspect of the armed Aphrodite that Greeks had inherited from the East, where the goddess Ishtar "remained a goddess of war, and Venus could bring victory to a Sulla or a Caesar."[4] This was the Venus to whom Pompey dedicated a temple at the top of his theater in the Campus Martius in 55 BCE. There was also a shrine to Venus Victrix on the Capitoline Hill, and festivals to her on August 12 and October 9. A sacrifice was annually dedicated to her on the latter date. In neo-classical art, this title is often used in the sense of 'Venus Victorious over men's hearts' or in the context of the Judgement of Paris (eg Canova's Venus Victrix, a half-nude reclining portrait of Pauline Bonaparte).

Other significant epithets for Venus included Venus Amica ("Venus the Friend"), Venus Armata ("Armed Venus"), Venus Caelestis ("Celestial Venus"), and Venus Aurea ("Golden Venus").

Venus Astronomical symbol of Venus
Venus
Venus in real color
Designations
Adjective Venusian or (rarely) Cytherean, Venerean
Epoch J2000
Aphelion 108,942,109 km
0.728 231 28 AU
Perihelion 107,476,259 km
0.718 432 70 AU
Semi-major axis 108,208,930 km
0.723 332 AU
Eccentricity 0.006 8
Orbital period 224.700 69 day
0.615 197 0 yr
Synodic period 583.92 days[1]
Average orbital speed 35.02 km/s
Inclination 3.394 71°
3.86° to Sun's equator
Longitude of ascending node 76.670 69°
Argument of perihelion 54.852 29°
Satellites None
Physical characteristics
Mean radius 6 051.8 ± 1.0 km[2]
0.949 9 Earths
Flattening < id="cite_ref-Seidelmann2007_1-1" class="reference">[2]
Surface area 4.60×108 km²
0.902 Earths
Volume 9.38×1011 km³
0.857 Earths
Mass 4.868 5×1024 kg
0.815 Earths
Mean density 5.204 g/cm³
Equatorial surface gravity 8.87 m/s2
0.904 g
Escape velocity 10.46 km/s
Sidereal rotation
period
243.018 5 day
Equatorial rotation velocity 6.52 km/h (1.81 m/s)
Axial tilt 177.3°[1]
North pole right ascension 18 h 11 min 2 s
272.76°[3]
North pole declination 67.16°
Albedo 0.65[1]
Surface temp.
Kelvin
Celsius
min mean max

735 K[4][5]

461.85 °C
Apparent magnitude up to -4.6[1]
Angular diameter 9.7" — 66.0"[1]
Atmosphere
Surface pressure 9.3 MPa
Composition ~96.5% Carbon dioxide
~3.5% Nitrogen
0.015% Sulfur dioxide
0.007% Argon
0.002% Water vapor
0.001 7% Carbon monoxide
0.001 2% Helium
0.000 7% Neon
trace Carbonyl sulfide
trace Hydrogen chloride
trace Hydrogen fluoride

Selasa, 30 Desember 2008

VENUS


Venus (Greek: Aphrodite; Babylonian: Ishtar) is the goddess of love and beauty. The planet is so named probably because it is the brightest of the planets known to the ancients. (With a few exceptions, the surface features on Venus are named for female figures.)

Venus has been known since prehistoric times. It is the brightest object in the sky except for the Sun and the Moon. Like Mercury, it was popularly thought to be two separate bodies: Eosphorus as the morning star and Hesperus as the evening star, but the Greek astronomers knew better. (Venus's apparition as the morning star is also sometimes called Lucifer.)

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.

Venus surfaceVenera 9 surface photo
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
radar mapMagellan radar map (false color)
produced detailed maps of Venus' surface using radar. ESA's Venus Express is now in orbit with a large variety of instruments.

Venus' rotation is somewhat unusual in that it is both very slow (243 Earth days per Venus day, slightly longer than Venus' year) and retrograde. In addition, the periods of Venus' rotation and of its orbit are synchronized such that it always presents the same face toward Earth when the two planets are at their closest approach. Whether this is a resonance effect or merely a coincidence is not known.

Venus is sometimes regarded as Earth's sister planet. In some ways they are very similar:

  • Venus is only slightly smaller than Earth (95% of Earth's diameter, 80% of Earth's mass).
  • Both have few craters indicating relatively young surfaces.
  • Their densities and chemical compositions are similar.
Because of these similarities, it was thought that below its dense clouds Venus might be very Earthlike and might even have life. But, unfortunately, more detailed study of Venus reveals that in many important ways it is radically different from Earth. It may be the least hospitable place for life in the solar system.

VenusVenus in visible light from Galileo
The pressure of Venus' atmosphere at the surface is 90 atmospheres (about the same as the pressure at a depth of 1 km in Earth's oceans). It is composed mostly of carbon dioxide. There are several layers of clouds many kilometers thick composed of sulfuric acid. These clouds completely obscure our view of the surface. This dense atmosphere produces a run-away greenhouse effect that raises Venus' surface temperature by about 400 degrees to over 740 K (hot enough to melt lead). Venus' surface is actually hotter than Mercury's despite being nearly twice as far from the Sun.

Venus UVVenus in ultra-violet light
There are strong (350 kph) winds at the cloud tops but winds at the surface are very slow, no more than a few kilometers per hour.

Venus probably once had large amounts of water like Earth but it all boiled away. Venus is now quite dry. Earth would have suffered the same fate had it been just a little closer to the Sun. We may learn a lot about Earth by learning why the basically similar Venus turned out so differently.

Most of Venus' surface consists of gently rolling plains with little relief. There are also several broad depressions: Atalanta PlanitiaGuinevere Planitia,Lavinia Planitia. There two large highland areas: Ishtar Terra in the northern hemisphere (about the size of Australia) and Aphrodite Terra along the equator (about the size of South America). The interior of Ishtar consists mainly of a high plateau, Lakshmi Planum, which is surrounded by the highest mountains on Venus including the enormous Maxwell Montes.

Sif MonsSif Mons (Magellan radar)
Data from Magellan's imaging radar shows that much of the surface of Venus is covered by lava flows. There are several large shield volcanoes (similar to Hawaii or Olympus Mons) such as Sif Mons. Recently announced findings indicate that Venus is still volcanically active, but only in a few hot spots; for the most part it has been geologically rather quiet for the past few hundred million years.

There are no small craters on Venus. It seems that small meteoroids burn up in Venus' dense atmosphere before reaching the surface. Craters on Venus seem to come in bunches indicating that large meteoroids that do reach the surface usually break up in the atmosphere.

The oldest terrains on Venus seem to be about 800 million years old. Extensive volcanism at that time wiped out the earlier surface including any large craters from early in Venus' history.

Venusian coronaeCoronae
Venusian pancakesPancake volcanoes
Magellan's images show a wide variety of interesting and unique features including pancake volcanoes (left) which seem to be eruptions of very thick lava and coronae (right) which seem to be collapsed domes over large magma chambers.

The interior of Venus is probably very similar to that of Earth: an iron core about 3000 km in radius, a molten rocky mantle comprising the majority of the planet. Recent results from the Magellan gravity data indicate that Venus' crust is stronger and thicker than had previously been assumed. Like Earth, convection in the mantle produces stress on the surface. However on Venus the stress is relieved in many relatively small regions instead of being concentrated at the boundaries of large plates as is the case on Earth.

Venus has no magnetic field, perhaps because of its slow rotation.

Venus has no satellites, and thereby hangs a tale.

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.

www.nineplanets.org