Fri Apr 13, 2012, 12:28 PM
n2doc (43,961 posts)
My God It's full of Stars
In this image, the NASA/ESA Hubble Space Telescope has captured the brilliance of the compact centre of Messier 70, a globular cluster. Quarters are always tight in globular clusters, where the mutual hold of gravity binds together hundreds of thousands of stars in a small region of space. Having this many shining stars piled on top of one another from our perspective makes globular clusters a popular target for amateur skywatchers and scientists alike. Messier 70 offers a special case because it has undergone what is known as a core collapse. In these clusters, even more stars squeeze into the object's core than on average, such that the brightness of the cluster increases steadily towards its centre.
The legions of stars in a globular cluster orbit about a shared centre of gravity. Some stars maintain relatively circular orbits, while others loop out into the cluster's fringes. As the stars interact with each other over time, lighter stars tend to pick up speed and migrate out toward the cluster's edges, while the heavier stars slow and congregate in orbits toward the centre. This huddling effect produces the denser, brighter centres characteristic of core-collapsed clusters. About a fifth of the more than 150 globular clusters in the Milky Way have undergone a core collapse.
Although many globular clusters call the galaxy's edges home, Messier 70 orbits close to the Milky Way's centre, around 30 000 light-years away from the Solar System. It is remarkable that Messier 70 has held together so well, given the strong gravitational pull of the Milky Way's hub.
Messier 70 is only about 68 light-years in diameter and can be seen, albeit very faintly, with binoculars in dark skies in the constellation of Sagittarius (The Archer). French astronomer Charles Messier documented the object in 1780 as the seventieth entry in his famous astronomical catalogue.
This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. The field of view is around 3.3 by 3.3 arcminutes.
ESA/Hubble & NASA
12 replies, 3515 views
My God It's full of Stars (Original post)
Response to n2doc (Original post)
Fri Apr 13, 2012, 12:40 PM
longship (35,735 posts)
2. Globular clusters are beautiful
My fave is of course M13, the Hercules cluster, and the largest visible from my latitude (just below 45N). I like it from my 10" reflector. It looks like a gleaming plate of sparkling diamonds. Stunningly beautiful.
Thanks for the eye candy.
Response to Motown_Johnny (Reply #5)
Fri Apr 13, 2012, 10:04 PM
Fumesucker (45,851 posts)
6. Our local astronomy club has a 30" Newtonian..
We were looking at a globular cluster one night through it and I mentioned "Nightfall", nobody else had heard of it..
Response to Fumesucker (Reply #6)
Sat Apr 14, 2012, 07:17 AM
Motown_Johnny (21,944 posts)
7. Wow, the short story should be required reading
for astronomy buffs. Maybe you can just read it out loud one night while people are waiting for their turn at the telescope.
"Nightfall" is a 1941 science fiction short story by Isaac Asimov about the coming of darkness to the people of a planet ordinarily illuminated at all times on all sides. It was adapted into a novel with Robert Silverberg in 1990. The short story has been included into 48 anthologies, and has appeared in six collections of Asimov's stories. The Science Fiction Writers of America voted "Nightfall" the best science fiction short story written prior to the 1965 establishment of the Nebula Awards, in 1968, and included it in The Science Fiction Hall of Fame Volume One, 1929-1964.
The Novel is good too but not so much that people should be forced to read it (or have it read to them).
Response to Leontius (Reply #9)
Sat Apr 14, 2012, 08:03 PM
Motown_Johnny (21,944 posts)
10. It looks like they did it twice, in 1988 and again in 2000
Radio, film, television
Nightfall (CBC), a supernatural/horror radio series produced and aired by CBC Radio from 1980 to 1983
Nightfall (1957 film), a 1957 movie directed by Jacques Tourneur
Nightfall (1988 film), a 1988 adaptation of the Asimov short story
Nightfall (2000 film), a 2000 adaptation of the Asimov short story
Nightfall (2012 film), a 2012 action film directed by Chow Hin-yeung
Operation Nightfall, a fictional operation in the television series 24
But I never heard of them before (or if I did I forgot about them). Maybe I will try to look for them online.
Edit to add: The 2000 version in on Netflix and stars David Carradine
Planet Aeon's six suns keep it bathed in endless light. But darkness is coming. An archeological dig uncovers evidence of a celestial phenomenon that will bring with it the first nightfall in 1,000 years. As the planet is gripped in superstitious panic, scientists race to discover what the night will bring. This classic sci-fi thriller from Gwyneth Gibby stars David Carradine and is based on an award-winning story by Isaac Asimov.
David Carradine,Jennifer Burns,Joseph Hodge