Neith (hypothetical moon)
Encyclopedia
Neith is the name given to an object first sighted by Giovanni Cassini
, which he believed to be a moon
of Venus
. It has since been determined that no such moon exists.
In 1672, Giovanni Cassini found a small object close to Venus. He did not take great note of his observation, but, when he saw it again in 1686, he made a formal announcement of a possible moon of Venus.
The object was seen by many other astronomers over a large period of time: by James Short in 1740, by Andreas Mayer in 1759, by Joseph Louis Lagrange
in 1761, eighteen observations in 1761, including one in which a small spot was seen following Venus while Venus was in transit
across the Sun
, eight observations in 1764, and by Christian Horrebow
in 1768.
Many astronomers, however, failed to find any moon during their observations of Venus, including William Herschel
in 1768.
Cassini originally observed Neith to be one-fourth the diameter of Venus. In 1761, Lagrange announced that Neith's orbital plane
was perpendicular to the ecliptic
. In 1777, J.H. Lambert estimated its orbital period as eleven days and three hours.
In 1766, the director of the Vienna Observatory
speculated that the observations of the moon were optical illusions: the bright image of Venus, he said, was reflected in the eye
and back into the telescope
, creating a smaller secondary image.
In 1884, Jean-Charles Houzeau
, the former director of the Royal Observatory of Brussels suggested that the "moon" was actually a planet which orbited the Sun every 283 days. Such a planet would be in conjunction with Venus every 1080 days, which fit with the recorded observations. Houzeau was also the first to give the object the name Neith, after an Egyptian
goddess.
The Belgian Academy of Sciences
published a paper in 1887 which studied each reported sighting of Neith. Ultimately, they determined that most of the sightings could be explained by stars which had been in the vicinity of Venus, including Chi Orionis
, M Tauri, 71 Orionis, Nu Geminorum and Theta Librae
.
Giovanni Domenico Cassini
This article is about the Italian-born astronomer. For his French-born great-grandson, see Jean-Dominique Cassini.Giovanni Domenico Cassini was an Italian/French mathematician, astronomer, engineer, and astrologer...
, which he believed to be a moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
of Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
. It has since been determined that no such moon exists.
In 1672, Giovanni Cassini found a small object close to Venus. He did not take great note of his observation, but, when he saw it again in 1686, he made a formal announcement of a possible moon of Venus.
The object was seen by many other astronomers over a large period of time: by James Short in 1740, by Andreas Mayer in 1759, by Joseph Louis Lagrange
Joseph Louis Lagrange
Joseph-Louis Lagrange , born Giuseppe Lodovico Lagrangia, was a mathematician and astronomer, who was born in Turin, Piedmont, lived part of his life in Prussia and part in France, making significant contributions to all fields of analysis, to number theory, and to classical and celestial mechanics...
in 1761, eighteen observations in 1761, including one in which a small spot was seen following Venus while Venus was in transit
Astronomical transit
The term transit or astronomical transit has three meanings in astronomy:* A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point...
across the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, eight observations in 1764, and by Christian Horrebow
Christian Horrebow
Christian Pedersen Horrebow was a Danish astronomer of the 18th century. He was a son of Peder Horrebow, whom he succeeded as director of the observatory associated with the University of Copenhagen....
in 1768.
Many astronomers, however, failed to find any moon during their observations of Venus, including William Herschel
William Herschel
Sir Frederick William Herschel, KH, FRS, German: Friedrich Wilhelm Herschel was a German-born British astronomer, technical expert, and composer. Born in Hanover, Wilhelm first followed his father into the Military Band of Hanover, but emigrated to Britain at age 19...
in 1768.
Cassini originally observed Neith to be one-fourth the diameter of Venus. In 1761, Lagrange announced that Neith's orbital plane
Orbital plane
Orbital plane may refer to:*Orbital plane *In anatomy, it refers to a specific area of the maxilla...
was perpendicular to the ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
. In 1777, J.H. Lambert estimated its orbital period as eleven days and three hours.
In 1766, the director of the Vienna Observatory
Vienna Observatory
Universitäts-Sternwarte Wien is an astronomical observatory in Vienna, Austria. It is part of the University of Vienna. The first observatory was built in 1753–1754 on the roof of one of the university buildings....
speculated that the observations of the moon were optical illusions: the bright image of Venus, he said, was reflected in the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
and back into the telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
, creating a smaller secondary image.
In 1884, Jean-Charles Houzeau
Jean-Charles Houzeau
Jean-Charles Houzeau de Lehaie was a Belgian astronomer and journalist.-Life:He was born in Havré , then in the United Kingdom of the Netherlands, later in Belgium. From 1842, he worked as a voluntary assistant at the Brussels Observatory and began writing papers. He eventually became the...
, the former director of the Royal Observatory of Brussels suggested that the "moon" was actually a planet which orbited the Sun every 283 days. Such a planet would be in conjunction with Venus every 1080 days, which fit with the recorded observations. Houzeau was also the first to give the object the name Neith, after an Egyptian
Egyptian mythology
Ancient Egyptian religion was a complex system of polytheistic beliefs and rituals which were an integral part of ancient Egyptian society. It centered on the Egyptians' interaction with a multitude of deities who were believed to be present in, and in control of, the forces and elements of nature...
goddess.
The Belgian Academy of Sciences
The Royal Academies for Science and the Arts of Belgium
There are two Royal Academies for Science and the Arts in Belgium, corresponding to the two main languages of the country, Dutch and French . The Academies are located in the Palace of Academies in Brussels....
published a paper in 1887 which studied each reported sighting of Neith. Ultimately, they determined that most of the sightings could be explained by stars which had been in the vicinity of Venus, including Chi Orionis
Chi Orionis
Chi Orionis is the name of two stars:* Chi1 Orionis * Chi2 Orionis...
, M Tauri, 71 Orionis, Nu Geminorum and Theta Librae
Theta Librae
Theta Librae is a giant star in the constellation Libra. It is located about 163 light years from the Earth and has an estimated mass about 84% greater than the Sun....
.
See also
- List of hypothetical astronomical objects
- 2002 VE682002 VE68' is a quasi-satellite of Venus. It was discovered on November 11, 2002.This asteroid is also a Mercury grazer and an Earth crosser; it seems to have been co-orbital with Venus for only the last 7000 years, and is destined to be ejected from this orbital arrangement about 500 years from now...
, a quasi-satelliteQuasi-satelliteA quasi-satellite is an object in a 1:1 orbital resonance with its planet that stays close to the planet over many orbital periods.A quasi-satellite's orbit around the Sun takes exactly the same time as the planet's, but has a different eccentricity , as shown in the diagram on the right...
of Venus