July 29, 2005 John Norris john@john-norris.net A Proposal: Audio Files for use while viewing subject. The following is a proposed file and text for wikipedia, or other community based process for creating content. In particular this "Audio Tour" is created to be used while viewing the astronomical object M13. The audio file is temporarily kept at: http://home.comcast.net/~john_norris_test/m13/audio_tour_m13.ogg Text Follows: == M-13 The Great Globular Cluster in Hercules- Audio Tour (English) == [[media:en_Audio_Tour_M13.ogg]] (Text for the Wikipedia Audio Tour for M-13) High in the night time summer skies of North America strides the constellation Hercules. The mighty god Hercules was revered by the Greeks for his strength. Indeed, the constellation named after him is the 5th largest of all the 88 modern constellations and features the brightest globular cluster (apparent Magnitude of 5.8) seen from this hemisphere- Messier number 13. [[#Notes|1]] M-13, also known as NGC 6205, or The Great Globular Cluster in Hercules, is shown in some drawings of the constellation to be on the left side of Hercules' chest. Alternatively, Hercules can be drawn so that M13 is to one side of his head. [[#Notes|2]] M13 is also part of the group of four stars creating "The Keystone" asterism [[#Notes|3]] Looking at M13 from a modern perspective, shows that it resides outside the Milky Way's galactic disk. You are looking beyond the flat plane where the earth resides in the Milky Way's spiral arms. M13 is in the Milky Way's halo a sphere of material extending in all directions from the Milk Way's center out to 100,000 light years. [[#Notes|4]] M13 itself is over 20,000 light years from earth. [[#Notes|5]] 20,000 years ago the photons making the journey to your eyes were just leaving M13. 20,000 years ago on earth, the last ice age was at its peak, lower Sea Levels were allowing people to walk across the Bering Straight to North America [[#Notes|6]] , the Great Barrier Reef was beginning to form [[#Notes|7]] , and Saber Toothed Cats and Wooly Mammoths roamed the earth. [[#Notes|8]] M13 is, of course, considerably older. Forming long before the Earth, it may be one of the oldest type of objects in the universe. In front of you is a something that is perhaps 10 to 15 billion years old [[#Notes|9]] M13 is massive. While a common test for good viewing is to see M13 with the naked eye[[#Notes|10]] , to really appreciate M13 takes a bit more power and understanding. A 4 inch telescope will show hundreds of stars, and 8 inch scope gives a view that Sue French and Alan Dyer describe as "a splattering of sugar grains sparkling in front of a dimmer glow of unresolved stars." [[#Notes|11]] Larger scopes have resolved about 30,000 stars, with the center too dense to count. [[#Notes|12]] However, M13 is estimated to have 1 million stars. While M13 takes up 20 arc minutes of our sky [[#Notes|13]] , about 2/3 the size of the moon, just the central part is 100 light years in diameter [[#Notes|14]] . Here, in the center, there would be one star for every cubic light year[[#Notes|15]]. The closest star to our earth is Proxima Centauri at almost 4 light years away. [[#Notes|16]] Imagine sitting on a planet of a sun in the center of M13- the sky would be dense with stars as bright as Venus. [[#Notes|17]] In our sky M13 has been "re-discovered" as a comet. As many people turned their eyes to the sky during Comet Halley's approach in 1986, folks saw the fuzzy patch of M13 and reported it a comet [[#Notes|18]] On November 16, 1974 M13 was sent a radio message from Earth. During the dedication of a major upgrade to the 1000 feet in diameter Arecibo radio telescope a radio transmission was sent. It was the first deliberate message to extraterrestrials and consisted of basic information about humans and science. The act was mostly symbolic as M13 will have moved by the time the message gets there. However somewhere between you and M13 is that radio transmission, still traveling out further out into space. [[#Notes|19]] Since you are in the neighborhood, you might also check out m57, the Ring Nebula in the constellation Lyra, Music provided by Philip Chavaroche, and is licensed under a Creative Commons Attribution ShareAlike license 2.0 . ( track N3, Voyage Cosmique; via Opsound.org; http://perso.wanadoo.fr/philippechavaroche/) This audio file and corresponding text licensed under the Creative Commons Attribution ShareAlike 2.0 license. =NOTES= # http://en.wikipedia.org/wiki/Hercules_(constellation) 7/15/05 # http://en.wikipedia.org/wiki/Hercules_(constellation) 7/15/05 # Jeff Kanipe (2000). "A Sky Watcher's Year". Cambridge University Press, Cambridge UK pg 81 # Iain Nicolson" (1999). "Unfolding Our Universe". Cambridge University Press, Cambridge UK pg 199 # " Astronomy Picture of the Day August 19, 1998" Robert Nemiroff (MTU) & Jerry Bonnell (USRA) # "Summary of 100,000 Years" National Climatic Data Center Paleoclimatology Program http://www.ngdc.noaa.gov/paleo/ctl/100k.html Retrieved 7/15/05 # "How the Great Barrier Reef was formed" Australian Institute of Marine Science Retrived7/15/05 # "Mammoth Hairy" Anna http://trillian.com/animals/mammoth.htm Retrieved 7/18/05 # "A Sky Watcher's Year" pg 81 # Guy Consolmagno Dan M Davis (2000). "Turn Left at Orion" Cambridge University Press, Cambridge UK pg 102 # Retrieved 7/15/05 # "Turn Left at Orion" pg 103 # Wil Tirion and Brian Skiff (2000) "Bright Star Atlas" Willmann-Bell, Inc Richmond Virginia # Ibid # "A Sky Watcher's Year" pg 80 # Retrieved 7/15/05 # "A Sky Watcher's Year" pg 80 # "A Sky Watcher's Year" pg 79 # Retrieved 7/16/05