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Celestial cartography

From Wikipedia, the free encyclopedia

Title page of the Coelum Stellatum Christianum by Julius Schiller.
Title page of the Coelum Stellatum Christianum by Julius Schiller.
This print, published in Richard Blome's "The Gentleman's Recreation" (1686) shows the diverse ways in which cosmography can be applied
This print, published in Richard Blome's "The Gentleman's Recreation" (1686) shows the diverse ways in which cosmography can be applied

Celestial cartography,[1] uranography,[2][3] astrography or star cartography[citation needed] is the fringe of astronomy and branch of cartography concerned with mapping stars, galaxies, and other astronomical objects on the celestial sphere. Measuring the position and light of charted objects requires a variety of instruments and techniques. These techniques have developed from angle measurements with quadrants and the unaided eye, through sextants combined with lenses for light magnification, up to current methods which include computer-automated space telescopes. Uranographers have historically produced planetary position tables, star tables, and star maps for use by both amateur and professional astronomers. More recently computerized star maps have been compiled, and automated positioning of telescopes is accomplished using databases of stars and other astronomical objects.

YouTube Encyclopedic

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  • ✪ History of Astronomy Part 2: Early Measurements of the Earth
  • ✪ Eyes On The Sky - Space Documentary
  • ✪ Introduction to Relocational Astrology and AstroCartography

Transcription

It’s Professor Dave, let’s take some measurements. We just talked about a few of the observations of the night sky that must have happened in every civilization throughout the world at the dawn of human history. But science is much more than just observation. It is about what we do with these observations. We look for explanations. We make models, and predictions. We take measurements, and see how they hold up to our predictions. If they don’t match, we revise the model and try again. After many centuries of pure observation, our approach to astronomy became more mathematical. Some of the earliest known scientific calculations happened during the classical period of astronomy, in Ancient Greece and other contemporaneous civilizations. What were some of these calculations, and what did they tell us? First came the realization that the earth is round. This idea first cropped up around the time of Pythagoras, although at that time it was not really based on logic but rather on the aesthetic beauty and perfection of the sphere, so it wasn’t very scientific. But just a bit later, with Aristotle, a more logical approach arose. He noticed that during a lunar eclipse, the shadow cast on the moon by the earth has a curved edge. This is representative of earth’s spherical shape. It was also realized that the stars that are visible in the night sky depended entirely on one’s location in the world. Moving north to south, a completely new set of stars becomes visible, and all the familiar ones vanish from sight. This is easily explained with a round earth, as the other half of space that surrounds the earth is only visible to the other half of the earth. Once it was determined that the earth is spherical, the next logical step was to attempt to measure the dimensions of the sphere. Eratosthenes was the first to do this, and with impressive accuracy. He reasoned that when the sun is directly overhead one object, it must cast a shadow on some other object sufficiently far away. He used a well in one part of Egypt, and an obelisk in another part of Egypt to take some measurements. At noon on the summer solstice, the sun shone directly down the well, illuminating the very bottom. Simultaneously, the sun cast a shadow on the obelisk in Alexandria revealing that the sun was seven degrees off the vertical. Now let’s draw a line from the bottom of the well to the center of the earth, and another one back up to the base of the obelisk. By simple geometry, we can see that the angle of this sector is seven degrees, which means that this distance represents a little less than a fiftieth of the way around the world. The distance between these locations was known to be five thousand stadia, so we can use a simple ratio to deduce that the circumference is around 250 thousand stadia, which is around 25 thousand miles. Given that in ancient times, the only tool available was the naked eye, these are all demonstrations that you can reproduce yourself, in case you’re curious to try. Now that we are all set with the earth, what about the distances to other objects in the sky? And how big are those? Incredibly, we were able to deduce some of these quantities as well. Take the moon for example. Around the time of Eratosthenes, another Greek named Aristarchus did some similar work. He looked at the shadow of the earth on the moon during a lunar eclipse and by comparing the curvature of the shadow and the moon itself, he deduced that the moon must have a diameter around one third that of earth. He also made estimates regarding the relative distances to the moon and sun, and although those were not as correct as his other work, he was the first to suggest that the sun is much larger than the earth, and even proposed that the earth goes around the sun. There was not sufficient evidence for this idea at the time, so the geocentric model with the rotating celestial sphere reigned supreme for many more centuries. Eventually, we did correct this oversight, and as this was one of the defining paradigm shifts in the history of astronomy, let’s move forward and talk about that next.

Contents

Etymology

The word "uranography" derived from the Greek "ουρανογραφια" (Koine Greek ουρανος "sky, heaven" + γραφειν "to write") through the Latin "uranographia". In Renaissance times, Uranographia was used as the book title of various celestial atlases.[4][5][6] During the 19th century, "uranography" was defined as the "description of the heavens". Elijah H. Burritt re-defined it as the "geography of the heavens".[7] The German word for uranography is "Uranographie", the French is "uranographie" and the Italian is "uranografia".

Astrometry

Star catalogues

Hyg-aqr.png
Bay-aqr.png
Aqr-kstars.png
Aquarius according to
Hyginus
Aquarius according to
Johann Bayer's Uranometria,
based on Rudolphine Tables
Aquarius according to
KStars

A determining fact source for drawing star charts is naturally a star table. This is apparent when comparing the imaginative "star maps" of Poeticon Astronomicon – illustrations beside a narrative text from the antiquity – to the star maps of Johann Bayer, based on precise star-position measurements from the Rudolphine Tables by Tycho Brahe.

Important historical star tables

Star atlases

Naked-eye

Telescopic

Photographic

  • 1914 Franklin-Adams Charts, by John Franklin-Adams, a very early photographic atlas.
  • The Falkau Atlas (Hans Vehrenberg). Stars to magnitude 13.
  • Atlas Stellarum (Hans Vehrenberg). Stars to magnitude 14.
  • True Visual Magnitude Photographic Star Atlas (Christos Papadopoulos). Stars to magnitude 13.5.
  • The Cambridge Photographic Star Atlas, Axel Mellinger and Ronald Stoyan, 2011. Stars to magnitude 14, natural color, 1°/cm.

Modern

  • Bright Star AtlasWil Tirion (stars to magnitude 6.5)
  • Cambridge Star AtlasWil Tirion (Stars to magnitude 6.5)
  • Norton's Star Atlas and Reference Handbook – Ed. Ian Ridpath (stars to magnitude 6.5)
  • Stars & Planets GuideIan Ridpath and Wil Tirion (stars to magnitude 6.0)[9]
  • Cambridge Double Star Atlas – James Mullaney and Wil Tirion (stars to magnitude 7.5)
  • Cambridge Atlas of Herschel Objects – James Mullaney and Wil Tirion (stars to magnitude 7.5)
  • Pocket Sky Atlas – Roger Sinnott (stars to magnitude 7.5)
  • Deep Sky Reiseatlas – Michael Feiler, Philip Noack (Telrad Finder Charts – stars to magnitude 7.5)
  • Atlas Coeli Skalnate Pleso (Atlas of the Heavens) 1950.0 – Antonín Bečvář (stars to magnitude 7.75 and about 12000 clusters, galaxies and nebulae)
  • SkyAtlas 2000.0, second edition – Wil Tirion & Roger Sinnott (stars to magnitude 8.5)
  • 1987, Uranometria 2000.0 Deep Sky AtlasWil Tirion, Barry Rappaport, Will Remaklus (stars to magnitude 9.7; 11.5 in selected close-ups)
  • Herald-Bobroff AstroAtlas – David Herald & Peter Bobroff (stars to magnitude 9 in main charts, 14 in selected sections)
  • Millennium Star Atlas – Roger Sinnott, Michael Perryman (stars to magnitude 11)
  • Field Guide to the Stars and PlanetsJay M. Pasachoff, Wil Tirion charts (stars to magnitude 7.5)
  • SkyGX (still in preparation) – Christopher Watson (stars to magnitude 12)
  • The Great Atlas of the Sky – Piotr Brych (2,400,000 stars to magnitude 12, galaxies to magnitude 18).[10]

Computerized

Free and printable from files

See also

References

  1. ^ Warner, D. J. (1979). The Sky Explored: Celestial Cartography 1500–1800. Amsterdam and New York: Theatrum Orbis Terrarum Ltd. and Alan R. Liss, Inc.
  2. ^ Lovi, G.; W. Tirion; B. Rappaport (1987). "Uranography Yesterday and Today". Uranometria 2000.0. 1: The Northern Hemisphere to – 6 degree. Willmann-Bell, Richmond.
  3. ^ Lovi, G.; Tirion, W. (1989). Men, Monsters and the Modern Universe. Richmond: Willmann-Bell.
  4. ^ 1690: Hevelius J., Firmamentum Sobiescianum sive Uranographia.
  5. ^ c. 1750: Bevis J., Uranographia Britannica.
  6. ^ 1801: Bode. J. E., Uranographia sive Astrorum Descriptio.
  7. ^ Burritt, E. H., The Geography of the Heavens, 1833.
  8. ^ "Dürer's hemispheres of 1515 — the first European printed star charts". Ianridpath.com. Retrieved 2019-02-25.
  9. ^ "Stars & Planets Guide", IanRidpath.com.
  10. ^ "The Great Atlas of the Sky", GreatSkyAtlas.com, December 1, 2009.
  11. ^ "Stellarmap.com". Stellarmap.com. Retrieved 2019-02-25.

External links

This page was last edited on 1 November 2019, at 21:16
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