Transit of Venus

A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black dot moving across the face of the Sun; the duration of such transits is several hours. A transit is similar to a solar eclipse by the Moon. While the diameter of Venus is more than three times that of the Moon, Venus appears smaller, travels more across the face of the Sun, because it is much farther away from Earth. Transits of Venus are among the rarest of predictable astronomical phenomena, they occur in a pattern that repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The periodicity is a reflection of the fact that the orbital periods of Earth and Venus are close to 8:13 and 243:395 commensurabilities; the last transit of Venus was on 5 and 6 June 2012, was the last Venus transit of the 21st century.

The previous pair of transits were in December 1874 and December 1882. The next transits of Venus will take place on 10–11 December 2117 and 8 December 2125. Venus transits are of great scientific importance as they were used to gain the first realistic estimates of the size of the Solar System. Observations of the 1639 transit, combined with the principle of parallax, provided an estimate of the distance between the Sun and the Earth, more accurate than any other up to that time; the 2012 transit provided scientists with a number of other research opportunities in the refinement of techniques to be used in the search for exoplanets. Venus, with an orbit inclined by 3.4° relative to the Earth's appears to pass under the Sun at inferior conjunction. A transit occurs when Venus reaches conjunction with the Sun at or near one of its nodes—the longitude where Venus passes through the Earth's orbital plane —and appears to pass directly across the Sun. Although the inclination between these two orbital planes is only 3.4°, Venus can be as far as 9.6° from the Sun when viewed from the Earth at inferior conjunction.

Since the angular diameter of the Sun is about half a degree, Venus may appear to pass above or below the Sun by more than 18 solar diameters during an ordinary conjunction. Sequences of transits repeat every 243 years. After this period of time Venus and Earth have returned to nearly the same point in their respective orbits. During the Earth's 243 sidereal orbital periods, which total 88,757.3 days, Venus completes 395 sidereal orbital periods of 224.701 days each, equal to 88,756.9 Earth days. This period of time corresponds to 152 synodic periods of Venus; the pattern of 105.5, 8, 121.5 and 8 years is not the only pattern, possible within the 243-year cycle, because of the slight mismatch between the times when the Earth and Venus arrive at the point of conjunction. Prior to 1518, the pattern of transits was 8, 113.5 and 121.5 years, the eight inter-transit gaps before the AD 546 transit were 121.5 years apart. The current pattern will continue until 2846, when it will be replaced by a pattern of 105.5, 129.5 and 8 years.

Thus, the 243-year cycle is stable, but the number of transits and their timing within the cycle will vary over time. Since the 243:395 Earth:Venus commensurability is only approximate, there are different sequences of transits occurring 243 years apart, each extending for several thousand years, which are replaced by other sequences. For instance, there is a series which ended in 541 BC, the series which includes 2117 only started in AD 1631. Ancient Indian, Egyptian and Chinese observers knew of Venus and recorded the planet's motions; the early Greek astronomers called Venus by two names—Hesperus the evening star and Phosphorus the morning star. Pythagoras is credited with realizing. There is no evidence. Venus was important to ancient American civilizations, in particular for the Maya, who called it Noh Ek, "the Great Star" or Xux Ek, "the Wasp Star". In the Dresden Codex, the Maya charted Venus's full cycle, but despite their precise knowledge of its course, there is no mention of a transit.

However, it has been proposed that frescoes found at Mayapan may contain a pictorial representation of the 12th or 13th century transits. The Persian polymath Avicenna claimed to have observed Venus as a spot on the Sun; this is possible, as there was a transit on May 24, 1032, but Avicenna did not give the date of his observation, modern scholars have questioned whether he could have observed the transit from his location at that time. He used his transit observation to help establish that Venus was, at least sometimes, below the Sun in Ptolemaic cosmology, i.e. the sphere of Venus comes before the sphere of the Sun when moving out from the Earth in the prevailing geocentric model. In 1627, Johannes Kepler became the first person to predict a transit of Venus, by predicting the 1631 event, his methods were not sufficiently accurate to predict that the transit would not be visible in most of Europe, as a consequence, nobody was able to use his prediction to observe the phenomenon. The first recorded observation of a transit of Venus was made by Jeremiah Horrocks from his home at Carr House in Much Hoole, near Preston in England, on 4 December 1639.

His friend, Willi

Herty Field

Herty Field known as Alumni Athletic Field, was the original on-campus playing venue for football and baseball at the University of Georgia in Athens, Georgia. It opened in the Fall of 1891 and hosting the first UGA home football game against Mercer University on January 30, 1892. Before its use for athletics, the field was a marching ground. Under the direction of Dr. Charles Herty, a professor of Chemistry at UGA and the creator of the UGA varsity football and baseball teams, the field was landscaped to host games and practices for the University's varsity and intramural activities. Outside his faculty duties, Herty served as the Instructor in Physical Culture from 1894 to 1896 and as Physical Director from 1896 until his resignation from UGA in November 1901, he led efforts to improve the field including raising USD$1,900.00 in 1897 from UGA alumni to further landscape the field and build bleachers. The field was referred to as Alumni Athletic Field. Herty Field was converted into a parking lot in the 1940s.

Herty Field historical marker

Juan B. Ambrosetti Museum of Ethnography

The Juan B. Ambrosetti Museum of Ethnography is an Argentine museum maintained by the University of Buenos Aires School of Philosophy and Letters and located in Buenos Aires. An estate on an eight-hectare property in Buenos Aires' Nueva Pompeya ward became the site of a homemade museum in 1866, when 14-year-old Francisco Moreno and his father classified and mounted their extensive collection of fossils and artifacts, gathered in excursions along the property and surroundings; the younger Moreno organized his collection as a public display, with funding from the Province of Buenos Aires, inaugurated the Anthropology and Ethnography Museum of Buenos Aires in 1879. Featuring over 15,000 artifacts, the collection was transferred to the new La Plata Museum in 1888. Explorations in the Gran Chaco region conducted at the time by University of Buenos Aires naturalist Juan Bautista Ambrosetti led to an extensive, new collection, in 1904, the latter inaugurated the University of Buenos Aires Museum of Ethnography.

The museum became the first in Argentina to introduce guided excursions for its patrons, travels along the Inca road system resulted in the 1908 discovery of Pucará de Tilcara, among the best-preserved ruins of settlements by Pre-Inca cultures in the area. Elaborate petroglyphs and over 3,000 other relics were recovered and catalogued in the following three years, most were added to the collections of the Museum of Ethnography; the settlement itself was declared a UNESCO World Heritage Site in 2003. Dr. Ambrosetti died in 1917, its management was continued by his collaborators, Drs. Salvador Debenedetti and Félix Outes; the museum was relocated to its present location in the city's Montserrat ward in 1927. Many of the collections of archeology and anthropology of the Bernardino Rivadavia Natural Sciences Museum were assigned to this museum in the decade of 1940, despite this, the institution became overshadowed, it was bolstered, however, by the 1958 creation of a Degree in Anthropology by the University of Buenos Aires, the institution was subsequently transferred to the university's School of Philosophy and Letters.

Official website