How do we know the location and distance of the galactic center?
820102
Well, we know that the galaxy is rotating, if for no other reason than by analogy with other galaxies we see in the universe which we can see rotating.  Moreover, we more or less know the basic shape of the galaxy, which is a rotating disk of stars with a central ball shaped bulge of stars (which also rotates, but the important thing here is the disk).  Additionally we can infer from observations that whatever the center of the galaxy is, we're not it.  :)\n\nUsing the doppler shifts of light, we can tell how fast other stars or clouds of dust in the galaxy are moving with respect to us (but only in the sense that this would be the speed if the star/dust was moving directly towards or away from us).  So, you measure the speed of things around the disk of the galaxy, and there will be four directions in which the speed you measure will be zero.  The final thing we do is look to see which direction has more "stuff".  The direction with more stars and dust (and the central bulge too) is the one which is the center of the galaxy.\n\nNow, if you're wondering why you just wouldn't look for the central bulge or the direction with more stars and dust, well, this will give you the general direction of the galactic center, but it's not very precise.  It's the astronomical equivalent of saying, "It's over that-away".  To get something more precise and exact, you need to do something else, which could be what I was saying above.  Above you would get four pretty precise and exact directions separated by 90 degrees on the sky, and all that's left is to tell which one is towards the center of the galaxy, which is when you fall back on the obvious method as the way to pick between the four more precise answers.  Basically, if you had a big compass engraved on a stone on the ground without any directions marked, having someone tell you that "North is that-away" gesturing in some direction will tell you which of the directions on the compass is north.\n\nOne interesting thing to note is that today our telescopes have improved to the point where we can take pictures of the center of the galaxy and see stars moving around it very quickly.  If we didn't know where the center of the galaxy was and had those pictures we could make a pretty good guess and say that that's where the center of the galaxy is.
1161939
This is difficult to answer.  Is there a galaxy destroyed everytime I clean my fingernails?\n\nI don't feel we have a good measure of what a galaxy is, our galaxy seems huge, yet we know very little about the boundaries (i.e. what if there were another galaxy right next to ours that we could not reach, like we were different slices of bread, intimately close, yet forever separated)
980491
Our solar system is located in the outer reaches of the Milky Way Galaxy, which is a spiral galaxy. The Milky Way Galaxy contains roughly 200 billion stars. Most of these stars are not visible from Earth. Almost everything that we can see in the sky belongs to the Milky Way Galaxy. \n\nThe sun is about 26,000 light-years from the center of the Milky Way Galaxy, which is about 80,000 to 120,000 light-years across (and less than 7,000 light-years thick). We are located on on one of its spiral arms, out towards the edge, called the "Orion Arm". \n\nIt takes the sun (and our solar system) roughly 200-250 million years to orbit once around the Milky Way. In this orbit, we (and the rest of the Solar System) are traveling at a velocity of about 155 miles/sec (250 km/sec). \n\nThe centre of the Milky Way Galaxy lies in the direction of the constellation Sagittarius.
495737
Smartie pants?\nEvidence points to a massive black hole at the center of the galaxy (Milky Way).  The black hole, with a mass more than three million times that of our sun, would appear to be in the constellation of Sagittarius.
22208
The Milky Way is the galaxy we live in. Our Solar System is inside some constelation within the galaxy. A Galaxy has millions of stars and Solar Systems.\n\nThe sun is far from being the origin of the Big Bang. It's just a REALLY REALLY small part of it.\n\nOh, Milky Way is also a chocolate bar.
1057373
When we look toward the galactic center we see a long, thin strip. This suggests a disk seen edge-on, rather than a ellipsoid or another shape. We can also detect the bulge at the center. Since we see spiral galaxies which are disks with central bulges, this is a bit of a tipoff. \n\nWhen we measure velocities of stars and gas in our galaxy, we see an overall rotational motion greater than random motions. This is another characteristic of a spiral.
429063
The Milky Way is moving at about 1,342,161 mph towards a galactic cluster known as Abell 3627\nhttp://answerway.com/expertans.php?category=243&expertname=Locii&catnam=Physics\n\nOur galaxy is NOT moving towards the center (or centre) of the universe. The universe has no center!\nhttp://sciastro.astronomy.net/sci.astro.9.FAQ\n\nGod should be spelled B-I-G B-A-N-G\nPBrax@netscape.com
429107
Our Galaxy has a bulge of stars at the center, wherein there may lie a giant black hole at the center. The galactic center lies in the direction of the constellation Sagittarius.\n\nRegular black holes are thought to form from heavy stars (perhaps those which start off with masses more than 20 or 25 times that of the Sun, but this is still an area of active research). When these stars end their lives in a supernova explosion, their cores collapse and gravity wins out over any other force that might be able to hold the star up.\n\nEventually, the star collapses so much that it is contained within its Schwarzschild radius, or event horizon, the boundary within which light cannot escape. At this point, the black hole is extremely tiny; a black hole with the mass of the Sun would fit in a small town, while one with the mass of the Earth would fit in the palm of your hand! The material inside the Schwarzschild radius will continue to collapse indefinitely, reaching the point where our understanding of the laws of physics breaks down. But no information from inside the Schwarzschild radius can escape to the outside world.\n\nSupermassive black holes, meanwhile, form differently - perhaps from the merger of many smaller black holes early in the universe's history - and grow over the years as they suck in gas from their surroundings. The formation of these objects and their relationship to the galaxy that harbors them is still an area of active research.\n\nWe have never sent anything to one.
362021
We can only give a rough guess as to how many galaxies there are, and it's billions at least. All but the closest ones visible as galaxies to the naked eye have names. Our local galaxy is the Milky Way, which you can see in a dark place on a clear night as a streak of stars running across the sky. A cluster is a group of galaxies.\n\nSome galaxies we have discovered with Hubble and other new telescopes seem to crashing into each other, and the Milky Way may be on its way to having a galactic interloper in the far future.
890850
Yes, our galaxy (and the local group) is generally heading in the direction of the virgo cluster of galaxies. All together, we are moving in the direction of a much larger structure called the 'Great Attractor' that is in the direction of the constallation of Centaurus. I'm guessing that this is what you heard about.\n\nhttp://en.wikipedia.org/wiki/Great_Attractor
818302
Firstly- 'miles' aren't the useful unit of measure here- they're far too small.\n\nWhile the galaxy is 100,000 light years in diameter- you don't need to travel 100,000 light years in order to leave it.  It's fairly flat- like a record er... uh.. .I mean CD.  Plus- we're about 2/3'rds of the way out on an arm.  So- you can leave in the plane of the galaxy and be pretty much outside of it in 20,000 light years.  Or- go out normal to (perpendicular to) the plane, and be out in about 5,000 light years.
1073938
Well dear....we aren't centrally placed in our milky way galaxy.....our solar system lies at a distance of about 30,000 light years from its centre....and we don't know the extremities of our universe yet hence our position with respect to the universe can't be measured..
699930
The Milky Way is the galaxy which is the home of our Solar System together with at least 200 billion other stars (more recent estimates have given numbers around 400 billion) and their planets, and thousands of clusters and nebulae.\nAs a galaxy, the Milky Way is actually a giant, as its mass is probably between 750 billion and one trillion solar masses, and its diameter is about 100,000 light years. Radio astronomial investigations of the distribution of hydrogen clouds have revealed that the Milky Way is a spiral galaxy.\nOur solar system is thus situated within the outer regions of this galaxy, well within the disk and only about 20 light years "above" the equatorial symmetry plane (to the direction of the Galactic North Pole, see below), but about 28,000 light years from the Galactic Center.
553690
The only direct way to measure a star's distance is by its parallax, but the accuracy of parallax get worse that farther away the star is, and at a distance of 1200 or more light years it is pretty bad. Recently the Hipparcos satellite was able to measure the parallax of thousands of stars to a precision never before obtained. You may be seeing distances from earlier measurements and the new Hipparcos data disagree by quite a bit for stars over a hundred or two light years away.
333419
Dubhe is 124 light years away from us.\nAlkaid is 100\nPhecda is 84\nAlioth is 81\nMegrez is 81\nMerak is 79\nMizar is 78\nDivide by 3.26 to get parsecs.
387950
That would be OGLE-2005-BLG-390Lb, a planet we belive to be orbiting around the star OGLE-2005-BLG-390L.  There is debate on if this detection is really a planet, as the technique used to find it was a one-shot event (gravitational micro-lensing), and can not be repeated.\n\nIf it is a planet it would be the most distant one we have ever found with a distance of between 18,200 and 24,800 light years away from us, in the direction of the galactic center.
247943
A planet is classified by its size/mass.  They are currently reveiwing the catagory, which may end up in pluto being excluded from the solar system.  \nAs far as getting to another galaxy, there is a way, we just haven't figured it out yet.  The closest galaxy is andromeda (sp), which is billions of lightyears away.  And since we can't even reach the speed of light, well, intergalactic travel isn't very likely in the near future.