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Showing posts with label Astronomy. Show all posts
Showing posts with label Astronomy. Show all posts

Friday, 21 October 2022

Lost star catalog of ancient times comes to light

 Around 130 BC, the great Greek astronomer Hipparchus drew up the very first star catalog ever, containing descriptions and coordinates of some 850 naked-eye stars in the northern sky.

At least, that's what later sources say - copies of Hipparchus's list have never been found. Until now, that is. Writing in the Journal of the History of Astronomy, three European scientists claim to have uncovered a small part of the long-lost catalog. "I felt nothing short of awe when I first heard about it," says astronomy historian and writer William Sheehan.

In the 2nd century AD, Claudius Ptolemy compiled a catalog of 1,025 stars in 48 constellations to include in his magnum opus, Almagest. Ptolemy also hinted at the existence of an earlier listing, some scholars have suggested that Ptolemy's work was based not on his own observations but on Hipparchus's catalog.

Hipparchus was born around 190 BC in Nicaea, in what is now northwestern Turkey, but he carried out most of his astronomical work on the island of Rhodes. He made the first estimates of the distances and sizes of the Moon and the Sun, and was the first to discover precession: the slow wobble in the orientation of the Earth's spin axis. According to astronomy historian Bradley Schaefer (Louisiana State University), Hipparchus was "arguably the best and greatest astronomer in the world before Copernicus."

"Only one of his many books, The Commentaries, has survived," says Schaefer, "with the most important loss being his influential star catalog." That's why scientists are elated about the new find. "It [...] illuminates a crucial moment in the birth of science, when astronomers shifted from simply describing the patterns they saw in the sky to measuring and predicting them," astronomy historian James Evans (University of Puget Sound, Washington) told Nature.

Peter Williams (Cambridge University, UK) and Victor Gysembergh and Emmanuel Zingg (Sorbonne University, Paris) studied the Codex Climaci Rescriptus, a 9th- or 10th-century manuscript from the Saint Catherine's Monastery on the Sinai peninsula in Egypt. The codex, which is now kept at the Museum of the Bible in Washington, D.C., contains Christian texts in Syriac...<<<Read More>>>...

Monday, 15 July 2013

Boötes Constellation

Constellation-Guide: Boötes constellation lies in the northern hemisphere. Its name comes from the Greek word Βοώτης, Boōtēs, which means ox driver, plowman, or herdsman. The correct pronunciation is /boʊˈoʊtɨs/, with each ‘o’ pronounced separately and stress on the second syllable. Boötes was first catalogued by the Greek astronomer Ptolemy in the 2nd century. The constellation is home to Arcturus, the third individual brightest star in the night sky, after Sirius in Canis Major and Canopus in Carina constellation.

Boötes is traditionally depicted as a herdsman with two hunting dogs on a leash and a club in his other hand. In the sky, Boötes follows Ursa Major around the pole. In one story, the constellation represents a ploughman driving the oxen in the Ursa Major constellation, followed by his two dogs, Asterion and Chara (represented by the constellation Canes Venatici, the Hunting Dogs). The ploughman’s oxen are tied to the polar axis and their movement keeps the skies in constant rotation ... read more>>>...