Diana (mythology)

In Roman mythology, Diana was the goddess of the hunt, being associated with wild animals and woodland, and also of the moon. In literature she was the equivalent of the Greek goddess Artemis, though in cult beliefs she was Italic, not Greek, in origin. Diana was worshipped in ancient Roman religion and is currently revered in the religions of Religio Romana Neopaganism and Stregheria.

Along with her main attributes, Diana was an emblem of chastity. Oak groves were especially sacred to her. According to mythology, Diana was born with her twin brother Apollo on the island of Delos, daughter of Jupiter and Latona. Diana made up a trinity with two other Roman deities: Egeria the water nymph, her servant and assistant midwife; and Virbius, the woodland god.

In the arts

Since the Renaissance the mythic Diana has often been expressed in the visual and dramatic arts, including the opera L'arbore di Diana. In the sixteenth century, Diana's image figured prominently at the Château de Fontainebleau, in deference to Diane de Poitiers, mistress of two French kings. At Versailles she was incorporated into the Olympian iconography with which Louis XIV, the Apollo-like "Sun King" liked to surround himself.

There are also references to her in common literature. In Shakespeare's play, Romeo and Juliet, many references are made to Diana. Rosaline, a beautiful woman who has sworn to chastity, is said to have "Dian's wit". Later on in the play, Romeo says, "It is the East, and Juliet is the sun. Arise fair sun, and kill the envious moon." He is saying that Juliet is better than Diana and Rosaline for not swearing chastity. Diana is also a character in the 1876 Leo Delibe ballet 'Sylvia'. The plot deals with Sylvia, one of Diana's nymphs and sworn to chastity and Diana's assault on Sylvia's affections for the shepherd Amyntas.

In Jean Cocteau's 1946 film La Belle et la Bête it is Diana's power which has transformed and imprisoned the beast.

In literature

In comic book lore, the character of Wonder Woman who hails from Paradise Island which is rich in Greek mythology is written to be a descendant of the Gods, and named after the moon goddess, Diana.

Diana, like many aspects of mythology, is depicted in the comic books Asterix. In the Roman temples, many times a statue of Diana can be seen in the background, depicted as a well rounded lady, usually sitting on a stag, who appears to be suffering.

In language

Both the Romanian word for "fairy", zânǎ^[6] and the Asturian word for "water nymph", xana, seem to come from the name of Diana.

moon

Moon

A full moon as seen by an observer on Earth
Designations
Adjective	"lunar"
Orbital characteristics
Perigee	363 104 km (0.002 4 AU)
Apogee	405 696 km (0.002 7 AU)
Semi-major axis	384 399 km (0.002 57 AU[1])
Eccentricity	0.054 9[1]
Orbital period	27.321 582 d (27 d 7 h 43.1 min[1])
Synodic period	29.530 588 d (29 d 12 h 44.0 min)
Average orbital speed	1.022 km/s
Inclination	5.145° to the ecliptic[1] (between 18.29° and 28.58° to Earth's equator)
Longitude of ascending node	regressing by one revolution in 18.6 years
Argument of perigee	progressing by one revolution in 8.85 years
Satellite of	Earth
Physical characteristics
Mean radius	1 737.10 km (0.273 Earths)[1][2]
Equatorial radius	1 738.14 km (0.273 Earths)[2]
Polar radius	1 735.97 km (0.273 Earths)[2]
Flattening	0.001 25
Circumference	10 921 km (equatorial)
Surface area	3.793 × 107 km² (0.074 Earths)
Volume	2.195 8 × 1010 km³ (0.020 Earths)
Mass	7.347 7 × 1022 kg (0.012 3 Earths[1])
Mean density	3 346.4 kg/m³[1]
Equatorial surface gravity	1.622 m/s² (0.165 4 g)
Escape velocity	2.38 km/s
Sidereal rotation period	27.321 582 d (synchronous)
Equatorial rotation velocity	4.627 m/s
Axial tilt	1.542 4° (to ecliptic) 6.687° (to orbit plane)
Albedo	0.12
Surface temp. equator 85°N[5]	min mean max 100 K 220 K 390 K 70 K 130 K 230 K
Apparent magnitude	−2.5 to −12.9[3] −12.74 (mean full moon)[2]
Angular diameter	29.3 to 34.1 arcminutes[2][4]

Some details of the Earth-Moon system. Besides the radius of each object, the radius to the Earth-Moon barycenter is shown. Photos from NASA. Data from NASA. Planets aren't spheres and orbits aren't circles, so numbers are only indicative. The Moon's orbital plane precesses about the Earth in an 18.6 year cycle. Its axis is located by Cassini's third law.

moon

The Moon (Latin: Luna) is Earth's only natural satellite and the fifth largest natural satellite in the Solar System.

The average centre-to-centre distance from the Earth to the Moon is 384,403 km, about thirty times the diameter of the Earth. The Moon's diameter is 3,474 km,^[6] a little more than a quarter that of the Earth. Thus, the Moon's volume is about 2 percent that of Earth; the pull of gravity at its surface is about 17 percent that at the Earth's surface. The Moon makes a complete orbit around the Earth every 27.3 days (the orbital period), and the periodic variations in the geometry of the Earth–Moon–Sun system are responsible for the lunar phases that repeat every 29.5 days (the synodic period).

The Moon is the only celestial body to which humans have travelled and upon which humans have performed a manned moon landing. The first artificial object to escape Earth's gravity and pass near the Moon was the Soviet Union's Luna 1, the first artificial object to impact the lunar surface was Luna 2, and the first photographs of the normally occluded far side of the Moon were made by Luna 3, all in 1959. The first spacecraft to perform a successful lunar soft landing was Luna 9; this was soon followed with the first successful lunar soft landing by Surveyor 1 and the first unmanned vehicle to orbit the Moon by Luna 10, all in 1966.^[6] The United States (U.S.) Apollo program achieved the only manned missions to date, resulting in six landings between 1969 and 1972. Human exploration of the Moon ceased with the conclusion of the Apollo program, although a few robotic landers and orbiters have been sent to the Moon since that time. Several countries have announced plans to return humans to the surface of the Moon in the 2020s.

Name and etymology

The proper English name for Earth's natural satellite is, simply, the Moon (capitalized).^[7][8] Moon is a Germanic word, related to the Latin mensis (month). It is ultimately a derivative of the Proto-Indo-European root me-, also represented in measure^[9] (time), with reminders of its importance in measuring time in words derived from it like Monday, month and menstrual. The related adjective is lunar, as well as an adjectival prefix seleno- and suffix -selene (from selēnē, the Ancient Greek word for the Moon). In English, the word moon exclusively meant "the Moon" until 1665, when it was extended to refer to the recently-discovered natural satellites of other planets.^[9] Subsequently, these objects were given distinct names in order to avoid confusion.^[8] The Moon is occasionally referred to by its Latin name Luna, primarily in science fiction.

Lunar surface

Main article: Geology of the Moon

Two sides of the Moon

The Moon is in synchronous rotation, meaning that it keeps nearly the same face turned towards the Earth at all times. Early in the Moon's history, its rotation slowed and became locked in this configuration as a result of frictional effects associated with tidal deformations caused by the Earth.^[10]

Long ago when the Moon spun much faster, its tidal bulge preceded the Earth-Moon line because the non-fluid crust could not rapidly adjust to keep this bulge in a direct line facing Earth.^[11] The Moon's rotation swept the bulge beyond the Earth-Moon line. The pull of gravity on the out-of-line bulge caused a torque, slowing the Moon spin, like a wrench tightening a nut. When the Moon's spin slowed enough to match its orbital rate, then the bulge always faced Earth (the bulge was in line with Earth), and the torque disappeared. That is why the Moon rotates at the same rate as it orbits and we always see the same side of the Moon.

Small variations (libration) in the angle from which the Moon is seen allow about 59% of its surface to be seen from the earth (but only half at any instant).^[6]

Near side of the Moon		Far side of the Moon

The side of the Moon that faces Earth is called the near side, and the opposite side the far side. The far side is often inaccurately called the "dark side," but in fact, it is illuminated exactly as often as the near side: once per lunar day, during the new moon phase we observe on Earth when the near side is dark. The far side of the Moon was first photographed by the Soviet probe Luna 3 in 1959. One distinguishing feature of the far side is its almost complete lack of maria.