How many black holes are there in each galaxy?
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Most astronomers believe that the Milky Way Galaxy -- the galaxy in which our solar system is located -- contains millions of black holes. Scientists have found a number of black holes in the Milky Way. These objects are in binary stars that give off X rays. A binary star is a pair of stars that orbit each other. \n\nhttp://www.nasa.gov/worldbook/blackhole_worldbook.html
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LAYMAN'S THEORY\n\nBlack holes are objects so massive and compact that no physical body or signal—not even light—can escape from their gravitational pull once it has crossed the so-called "event horizon" around the black hole (for a black hole of the mass of our sun the event horizon would have a radius of just 3 km, hence black holes are comparably small objects in astronomical terms). Besides the frequent stellar mass black holes (which are thought to be generated at the death of stars about 10 times or more massive than our sun) there is a second class of black holes, which reside in the centers of almost all galaxies and are a million to billion times as massive as our sun. Such so-called supermassive black holes are thought to be the central engine of "Quasars," the most distant and luminous objects known in the universe. Their electromagnetic emission is thought to arise when gas heats up to temperatures of million of degrees before falling beyond the event horizon of a supermassive black hole. In order to find evidence for the existence of such objects, one has to show that so much matter is concentrated in such a small volume that all alternatives to black hole can be excluded—e.g., dense clusters of dark astrophysical bodies such as planets, neutron stars, etc. This is a difficult task in extragalactic systems because of their incredibly large distance. The center of our home galaxy, the Milky Way, however, is about 100 times closer than our next major neighbour galaxy, the Andromeda galaxy. Therefore the undertaking of finding strong direct evidence for the existence of supermassive black holes is most easily done in the Milky Way. For probing the gravitational field at the center of the Milky Way one can use stars as test particles. Imagine the following scenario: If our sun did not give off any light, we would still know of its existence because the gravitational pull of the Sun (along with the angular momentum of the Earth) makes our home planet move around it once a year. In a similar way we have observed the movements of stars close to the supposed supermassive black hole, called Sagittarius A*, in the center of our Milky Way for over a decade. A star was found that moves around Sagittarius A* once every 15 years. By inferring the properties of its orbit with the help of Kepler's laws it was straightforward to show that the (dark) object that forces the star onto its orbit must have about 3.5 million times as much mass as our sun. Furthermore, this mass must be concentrated into a volume just about three times as large as our solar system. Since there is no other known physical object with these properties that can be stable over a significant length of time (compared to the lifetime of our galaxy of about 10 billion years) we concluded that the Sagittarius A* is indeed a supermassive black hole.
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Greetings,\n\nThe number that would answer your question has not been named yet.  There are billions of stars in our galaxy alone, and there are billions and billions of galaxies.\n\nWe will never know how many stars there are because there are literally too many to count.\n\n-matt
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There are _trillions_ of stars in the Universe.  Our galaxy, the Milky Way, is composed of 300 - 400 billion stars.  There are _billions_ of galaxies in the Universe, many dwarfing the size of ours.\n\nThe chance of other life _not_ being out there is so close to zero that it can't even be calculated.  There are infinite possibilities in this Universe, and we haven't begun to study more than a tiny bit of them.\n\nTo anybody that has the audacity to say "no" there isn't, then get an ego check.  We aren't the only intelligent life in a Universe of infinite possibilities.
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there are as many as 200 billion galaxies in the observable universe
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Yes!\n\nOur galaxy is rotating, in the sense that all the stars are in orbits around a common center, which happens to have a big black hole. Because the distribution of mass in something like a galaxy is different from a solar system, these orbits are not simple ellipses.\n\nIt takes the sun (and the rest of the solar system) about 250 million years to make it all the way around.\n\nOur Galaxy is also interacting with other galaxies, in particular with the Andromeda Galaxy which is, relatively speaking, close by.\n\nIn fact, our Galaxy and Andromeda are headed for a collision in about, oh, a few billion years. However the distance between stars in a galaxy is such that there will be fewm if any, star-star collisons.
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Black Holes are strongly suspected to be responsible for a few powerful X-ray stars, and also to be at the center of most Galaxies - including ours.\n\nBut, while these are all much to far away for us to get to now - probably ever. You can see what the trip would be like with the Virtual Trips to Black Holes and Neutron Stars web page:\nhttp://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html\nand with the animations on the Falling into a Black Hole page:\nhttp://casa.colorado.edu/~ajsh/schw.shtml
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Number of atoms in the universe:\n10^11 galaxies * 10^11 stars in each * 10^33 grams in each star * 6x10^23 atoms of hydrogen per gram = about 10^79 atoms.  There are probably more photons but photons are so. . . insubstantial. Neutrinos?  Well, you ever try to catch one? They are only slightly easier to find than ghosts.
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The spiral arms and the "halo" in the center, which is thought to be massive amounts of stars and light trapped in an extremly large black hole.\n\nAlso, there is evidence in super nova explosions that show the propable formations of large black holes and, eventually, galaxies.
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Sorry to Sun of Samsa.  I meant to give you a thumbs up!  The Black Hole Singularity is infinitely small (infinite density and ZERO volume).  The effects of the hole can be miles or light years across!
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Take into consideration the billions of stars in this galaxy. Then take into consideration the billions of galaxies in the local cluster. Then take into consideration the billions of clusters in the local supercluster. Then take into consideration the billions of superclusters in the local segment of the wall. Then take into consideration the billions of segments in the Great Wall. Then take into consideration the billions of walls in the Universe. It's even possible there's more than one universe! \n\nWhat do you believe? I think there is life out there. But are they sentient and advanced? Maybe. Maybe not.
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Ok, how about this:\n\nAstronomers estimate that there are at least 70 sextillion (7×10^22) stars in the known universe. That is 230 billion times as many as the 300 billion in our own Milky Way.\n\n(shamelessly stolen from Wikepedia)
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A galaxy is a swirling collection of stars. our own Milky Way galaxy contains hundreds of billions of stars, of which our sun is only one amongst these billions and billions.\n\nA solar system is just a single sun that has planets revolving around it. A galaxy is made up of billions of such suns. And some scientists believe that as many as 25% of the stars could have planets. That means billions and billions of solar systems in our own galaxy.\n\nHere'a a picture of our closest neighbor, the Andromeda galaxy. It has close to one-trillion stars.\n\nHope this heolps. Cheers\n\nhttp://en.wikipedia.org/wiki/Andromeda_Galaxy
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Solar winds,nebulars,planets,milky way,\nmeteors,comets,darkness,\nsolar systems,black holes,\npulsars,nova's,super nova's.\nsatalites,Asteroids.\nspiral galaxys,oval galaxys\nhelp u.
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"Our own Milky Way, a typical giant spiral galaxy, includes at least 100 billion stars in its diameter." \n100 billion\n\nEncyclopedia Britannica. Astronomy. 2000. "There are about 100 billion stars in the Milky Way Galaxy" \n100 billion\n\nEddington, A. S. The Interior of a Star. 1926. "The Sun belongs to a system containing some 3,000 million stars." 3 billion\n\nBoorstein, Daniel J. Discovery of the World. New York: Random House, 1983: 320. "...the Galaxy is nothing else but a mass of innumerable stars planted together in clusters."\ninnumerable\n\nButterworth, Paul. Stars in Our Galaxy. Ask a High-Energy Astronomer. 1998. "We can only see a few thousand stars at most with our unaided eyes. These are a mixture of stars which are nearby, and bright stars which are further away; but they are only a tiny fraction of the 100,000,000,000 stars in our own galaxy." \n100 billion
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No, but there are other Galaxies in the Universe
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Thirteen.\n\nOriginally it was thought there were the nine that were 'found' by Voyager 2 in 1986. Since then there's been more exploration and the discovery using the Hubble Telescope in December last year brought the current total to 13.  There's also incomplete rings called Ring Arcs