Lucius Lucretius Trio was a Roman moneyer, who minted two denarii in c. 76 BCE.
His coin showing the laureate head of Neptune is in the collections of the Museum of Fine Arts, Boston.
The other has a radiate Sol (Sun) on the obverse and a crescent moon and seven stars on the reverse. The stars are the Septem Triones (Ursa Major), a pun of the moneyer cognomen.
A lunar phase or Moon phase is the apparent shape of the Moon's directly sunlit portion as viewed from the Earth. Because the Moon is tidally locked with the Earth, the same hemisphere is always facing the Earth. In common usage, the four major phases are the new moon, the first quarter, the full moon and the last quarter; the four minor phases are waxing crescent, waxing gibbous, waning gibbous, and waning crescent. A lunar month is the time between successive recurrences of the same phase: due to the eccentricity of the Moon's orbit, this duration is not perfectly constant but averages about 29.5 days.
Nereid, or Neptune II, is the third-largest moon of Neptune. It has the most eccentric orbit of all known moons in the Solar System. It was the second moon of Neptune to be discovered, by Gerard Kuiper in 1949.
A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn, Uranus, and Neptune. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion.
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core, releasing this energy from its outer photosphere. Astronomers classify it as a G-type main-sequence star.
Triton is the largest natural satellite of the planet Neptune. It is the only moon of Neptune massive enough to be rounded under its own gravity and hosts a thin, hazy atmosphere. Triton orbits Neptune in a retrograde orbit—revolving in the opposite direction to the parent planet's rotation—the only large moon in the Solar System to do so. Triton is thought to have once been a dwarf planet from the Kuiper belt, captured into Neptune's orbit by the latter's gravity.
In Sabine and ancient Roman religion and myth, Luna is the divine embodiment of the Moon. She is often presented as the female complement of the Sun, Sol, conceived of as a god. Luna is also sometimes represented as an aspect of the Roman triple goddess, along with Diana and either Proserpina or Hecate. Luna is not always a distinct goddess, but sometimes rather an epithet that specializes a goddess, since both Diana and Juno are identified as moon goddesses.
A crescent shape is a symbol or emblem used to represent the lunar phase in the first quarter, or by extension a symbol representing the Moon itself.
Thalassa, also known as Neptune IV, is the second-innermost satellite of Neptune. Thalassa was named after sea goddess Thalassa, a daughter of Aether and Hemera from Greek mythology. "Thalassa" is also the Greek word for "sea".
Despina, also known as Neptune V, is the third-closest inner moon of Neptune. It is named after Greek mythological character Despoina, a nymph who was a daughter of Poseidon and Demeter.
Galatea, also known as Neptune VI, is the fourth-closest inner moon of Neptune, and fifth-largest moon of Neptune. It is named after Galatea, one of the fifty Nereids of Greek legend, with whom Cyclops Polyphemus was vainly in love.
Sailor Neptune is a fictional lead character in the Sailor Moon media franchise. Her alternate identity is Michiru Kaiou, a teenage Japanese schoolgirl and violinist. Michiru is a member of the Sailor Soldiers, female supernatural fighters who protect the Solar System from evil.
A classical planet is an astronomical object that is visible to the naked eye and moves across the sky and its backdrop of fixed stars. Visible to humans on Earth there are seven classical planets. They are from brightest to dimmest: the Sun, the Moon, Venus, Jupiter, Mars, Mercury and Saturn.
The conjoined representation of a crescent and a star is used in various historical contexts, including as a prominent symbol of the Ottoman Empire, and in contemporary times, as a national symbol by some countries, and as a symbol of Islam. It was developed in the Greek colony of Byzantium ca. 300 BC, though it became more widely used as the royal emblem of Pontic king Mithridates VI Eupator after he incorporated Byzantium into his kingdom for a short period. During the 5th century, it was present in coins minted by the Persian Sassanian Empire; the symbol was represented in the coins minted across the empire throughout the Middle East for more than 400 years from the 3rd century until the fall of the Sassanians after the Muslim conquest of Persia in the 7th century. The conquering Muslim rulers kept the symbol in their coinage during the early years of the caliphate, as the coins were exact replicas of the Sassanian coins.
The planet Neptune has 16 known moons, which are named for minor water deities and a water creature in Greek mythology. By far the largest of them is Triton, discovered by William Lassell on 10 October 1846, 17 days after the discovery of Neptune itself. Over a century passed before the discovery of the second natural satellite, Nereid, in 1949, and another 40 years passed before Proteus, Neptune's second-largest moon, was discovered in 1989.
The naming of moons has been the responsibility of the International Astronomical Union's committee for Planetary System Nomenclature since 1973. That committee is known today as the Working Group for Planetary System Nomenclature (WGPSN).
The definition of the term planet has changed several times since the word was coined by the ancient Greeks. Greek astronomers employed the term ἀστέρες πλανῆται, 'wandering stars', for star-like objects which apparently moved over the sky. Over the millennia, the term has included a variety of different celestial bodies, from the Sun and the Moon to satellites and asteroids.
Planetary symbols are used in astrology and traditionally in astronomy to represent a classical planet or one of the modern planets. The classical symbols were also used in alchemy for the seven metals known to the ancients, which were associated with the planets, and in calendars for the seven days of the week associated with the seven planets. The original symbols date to Greco-Roman astronomy; their modern forms developed in the 16th century, and additional symbols would be created later for newly discovered planets.
Neptune is the eighth and farthest known planet from the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth. Compared to its fellow ice giant Uranus, Neptune is slightly more massive, but denser and smaller. Being composed primarily of gases and liquids, it has no well-defined solid surface, and orbits the Sun once every 164.8 years at an orbital distance of 30.1 astronomical units. It is named after the Roman god of the sea and has the astronomical symbol , representing Neptune's trident.
In astrology, planets have a meaning different from the astronomical understanding of what a planet is. Before the age of telescopes, the night sky was thought to consist of two similar components: fixed stars, which remained motionless in relation to each other, and moving objects/"wandering stars", which moved relative to the fixed stars over the course of the year(s).
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