 | You can help expand this article with text translated from the corresponding article in Russian. (September 2011)Click [show] for important translation instructions.
|
Neith is a hypothetical natural satellite of Venus reportedly sighted by Giovanni Cassini in 1672 and by several other astronomers in following years. It was 'observed' up to 30 times by astronomers until 1770, when there were no new sightings and it was not found during the transit of Venus in 1761 and 1769. [1]
 |
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, another eighteen observations in 1761, including one in which a small spot was seen following Venus while the planet was in a transit across the Sun, eight observations in 1764, and by Christian Horrebow in 1768.
| Year | City | Person | Number of sightings |
|---|---|---|---|
| 1645 | Naples | Francesco Fontana | 3 |
| 1646 | Naples | Francesco Fontana | 1 |
| 1672 | Paris | Giovanni Domenico Cassini | 1 |
| 1686 | Paris | Giovanni Domenico Cassini | 1 |
| 1740 | London | James Short | 1 |
| 1759 | Greifswald | Andreas Mayer | 1 |
| 1761 | Marseilles | Joseph Lagrange | 3 |
| 1761 | Limoges | Jacques Montaingne | 4 |
| 1761 | St. Neots | unknown | 1 |
| 1761 | Greifswald | Friedrich Artzt | 1 |
| 1761 | Krefeld | Abraham Scheuten | 2 |
| 1761 | Copenhagen | Peter Roedkiær | 8 |
| 1764 | Copenhagen | Peter Roedkiær | 2 |
| 1764 | Copenhagen | Christian Horrebow and others | 3 |
| 1764 | Auxerre | Marian | 3 |
| 1768 | Copenhagen | Christian Horrebow | 1 |
Many astronomers 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. That same year, however, mathematician Jean le Rond d'Alembert wrote to Voltaire that Neith had "declined to follow his mistress during her passage over the sun", questioning whether Venus truly had a moon. [2] In 1766, the director of the Vienna Observatory speculated that the observations of the moon were optical illusions. He said: "the bright image of Venus was reflected in the eye and back into the telescope, creating a smaller secondary image." In 1777, J.H. Lambert estimated its orbital period as eleven days and three hours.
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.
An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three celestial objects is known as a syzygy. An eclipse is the result of either an occultation or a transit. A "deep eclipse" is when a small astronomical object is behind a bigger one.
Vulcan was a theorized planet that some pre-20th century astronomers thought existed in an orbit between Mercury and the Sun. Speculation about, and even purported observations of, intermercurial bodies or planets date back to the beginning of the 17th century. The case for their probable existence was bolstered by the support of the French mathematician Urbain Le Verrier, who had predicted the existence of Neptune using disturbances in the orbit of Uranus. By 1859 he had confirmed unexplained peculiarities in Mercury's orbit and predicted that they had to be the result of the gravitational influence of another unknown nearby planet or series of asteroids. A French amateur astronomer's report that he had observed an object passing in front of the Sun that same year led Le Verrier to announce that the long sought after planet, which he gave the name Vulcan, had been discovered at last.
The following is a timeline of Solar System astronomy and science. It includes the advances in the knowledge of the Earth at planetary scale, as part of it.
In astronomy, a transit is the passage of a celestial body directly between a larger body and the observer. As viewed from a particular vantage point, the transiting body appears to move across the face of the larger body, covering a small portion of it.
An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks from view (occults) an object in the background. In this general sense, occultation applies to the visual scene observed from low-flying aircraft when foreground objects obscure distant objects dynamically, as the scene changes over time.
Skathi, also named Saturn XXVII and originally spelled Skadi, is a natural satellite of the planet Saturn. Skathi is one of Saturn's irregular moons, in its Norse group of satellites. It was discovered on September 23, 2000, by a team of astronomers led by Brett Gladman. The team announced their discovery on December 7, 2000, along with seven other satellites of Saturn, namely; Tarvos, Ijiraq, Thrymr, Siarnaq, Mundilfari, Erriapus, and Suttungr. The moon was named after Skaði, a figure in Norse mythology, as part of an effort to diversify the largely Greek and Roman names of astronomical objects.
A transit of Venus takes place when Venus passes directly between the Sun and the Earth, becoming visible against the solar disk. During a transit, Venus can be seen as a small black circle moving across the face of the Sun.
A transit of a minor planet takes place when a minor planet passes directly between an observer and another heavenly body, obscuring a small part of that body's disc. From the perspective of observers on Earth, transits of the Sun and Moon by minor planets are very rare, as the minor planets orbiting between the Earth and those bodies are few and very small. Transits of the Sun would be more visible from the outer planets.
Solar eclipses on Jupiter occur when any of the natural satellites of Jupiter pass in front of the Sun as seen from the planet Jupiter.
Mercury is the closest planet to the Sun and lacks any natural satellites. An undiscovered moon orbiting the planet was hypothesized to exist in the early 1970s, but it turned out to be misinterpreted data from the star 31 Crateris. Observation of a moon of Mercury from Earth would be difficult because Mercury is relatively close to the Sun. For example, Mercury was not observed in the infrared spectrum until 1995. NASA's MESSENGER spacecraft, which orbited Mercury from 2011 to 2015, did not detect any moon. Mercury's small Hill sphere limits the potential for a natural satellite to exist.
GiovanniDomenico Cassini, also known as Jean-Dominique Cassini was an Italian mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the County of Nice, part of the Savoyard state. Cassini is known for his work on astronomy and engineering. He discovered four satellites of the planet Saturn and noted the division of the rings of Saturn; the Cassini Division was named after him. Giovanni Domenico Cassini was also the first of his family to begin work on the project of creating a topographic map of France.
Discovery and exploration of the Solar System is observation, visitation, and increase in knowledge and understanding of Earth's "cosmic neighborhood". This includes the Sun, Earth and the Moon, the major planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, their satellites, as well as smaller bodies including comets, asteroids, and dust.
Rømer's determination of the speed of light was the demonstration in 1676 that light has an apprehensible, measurable speed and so does not travel instantaneously. The discovery is usually attributed to Danish astronomer Ole Rømer, who was working at the Royal Observatory in Paris at the time.
Jean-Baptiste Chappe d'Auteroche was a French astronomer, best known for his observations of the transits of Venus in 1761 and 1769.
The history of Mars observation is about the recorded history of observation of the planet Mars. Some of the early records of Mars' observation date back to the era of the ancient Egyptian astronomers in the 2nd millennium BCE. Chinese records about the motions of Mars appeared before the founding of the Zhou dynasty. Detailed observations of the position of Mars were made by Babylonian astronomers who developed arithmetic techniques to predict the future position of the planet. The ancient Greek philosophers and Hellenistic astronomers developed a geocentric model to explain the planet's motions. Measurements of Mars' angular diameter can be found in ancient Greek and Indian texts. In the 16th century, Nicolaus Copernicus proposed a heliocentric model for the Solar System in which the planets follow circular orbits about the Sun. This was revised by Johannes Kepler, yielding an elliptic orbit for Mars that more accurately fitted the observational data.
C/1769 P1 (Messier) is a long-period comet that was visible to the naked eye at its last apparition in 1769. The comet is classified as a great comet due to its superlative brightness.
The following outline is provided as an overview of and topical guide to Venus:
The word "transit" refers to cases where the nearer object appears smaller than the more distant object. Cases where the nearer object appears larger and completely hides the more distant object are known as occultations.
| Geography | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Astronomy |
| ||||||||||||
| Exploration |
| ||||||||||||
| Related | |||||||||||||
