When was the center line axis of our galaxy, as it crosses the ecliptic, established, and by whom?
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The position of the center of our galaxy was first established by observations of globular clusters by Harlow Shapley.  Some clever guy (Jan Oort maybe?) did a careful study of stellar motions of stars around the sun assumed they were all orbiting something and deduced the center.  Both estimates were off because their distance estimates were wrong because no one understood how dust in the interstellar medium can make things fainter than they ought to be. \n\nSo that finds the center, a point on its rotational axis. . . . but...you ask about where it crosses the ecliptic.  . .that sounds like where the milky way cross the plane of the planets.  First guy who know about planets I guess saw that.  Some ancient somebody or other. . . .
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Our “address” is: \n\nThe third planet of the star “Sol”, which is the name of the sun. \n\nSol is about 27,000 light years from the center of the Milky Way galaxy, on the inner rim of the “Orion Arm”. The Milky Way galaxy—our galaxy—has four “spiral arms”. An “arm” of a galaxy is a very huge arc of stars that extend out from the center of the galaxy in a long spiral. \n\nThe "Milky Way" galaxy is in the “Local Group”. Galaxies are clustered into groups of galaxies, with wide areas of semi-nothingness between the groups. We have named the group of which our galaxy is part the “Local Group” for obvious reasons. \n\nThe “Local Group” is part of the “Virgo Supercluster”. A supercluster is a cluster of groups of galaxies. \n\nThe “Virgo Supercluster” is one of many clusters and superclusters in the known universe. There is no “official name” of our universe, since it is the only universe of which we know. It is therefore usually just called “the universe”. \n\nOur address is therefore the third planet of the star Sol, on the inner rim of the Orion Arm of the Milky Way galaxy, in the Local Group of galaxies, within the Virgo Supercluster, in "the universe". \n\nNow that you know the address, from whom are you expecting mail?
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All the objects in the Milky Way Galaxy orbit their common center of mass, called the Galactic Center. It includes the constellations Sagittarius, Scorpius, Ophiuchus and Scutum. For a great link that gives you a lot of specifics, including a map of the center check the sources below.
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A bunch of experts (astronomers, biologists, etc.) once met to answer your question in Greenbank, West Virginia in the 1960s.  They only concerned themselves with life in the Milky Way.  They developed a formula, sometimes called the "Drake Equation".  Depending on the numbers you place in the seven variables of the equation, you can come up with answers that range from "a million" down to "one" as the answer.
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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
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Uranus is in the middle
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I think you want Claudius Ptolemy, the Greek astronomer who lived in Alexandria Egypt in the second century.  His books Almagest and Tetrabiblios  were the authoritative works in astronomy  and astrology respectively, for centuries.\n\nHis astronomy placed Earth at the center of the universe, and used a complicated system of circles within circles to explain the motions of the planets. Nevertheless, it wasn't until Kepler (in the early 1600's) figured out that planets orbited the sun in elliptical orbits that anyone had a significantly more accurate way to calculate planetary positions.
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Us.  The Milky Way is the name of the galaxy in which we currently reside.  Aside from us, there are a lot of stars and planets and such.  There is a widespread belief that the center of the galaxy contains a black hole.
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There is a galactic alignment happening on December 21, 2012.   Due to precession of the equinoxes, on that day, the sun will appear to come up through the dark area in the center of the Milky Way. The ancient Maya believed that that spot was the center of the universe (and it's pretty close) and considered it the womb of the universe. So when the sun appears to come out of that spot, the sun is being born again. It's a new world. It's not that this world is ending (actually, it's already over), but the new world begins on that day.\nThe date on the Mayan Long Count calendar that day is 13.00.00.00.00 4 Ahau 3 Kankin.\nJohn Major Jenkins wrote an excellent book on the subject called Mayan Cosmogenesis 2012.\nI have a site and a couple of blogs on the Mayan and Aztec calendar and I've written a book called Jaguar Nights (unpublished) on the subject.
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Well you can't really have a center of the diameter line of a sphere.  But I guess the common dividing point would be where the prime merdian (zero degrees longitude) passes through the equator.  The intersection point is in the eastern Atlantic ocean, south of Ghana in Africa.
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angle b and angle c.\nthey are both on the same line of the x- axis and collide at a central point with respect to A.
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agonic line—The line through all points on the earth's surface at which the magnetic declination is zero; that is, the locus of all points at which magnetic north and true north coincide. \nThis line is a particular case of an isogonic line. The position of this line exhibits variations in time, but in 1995 was so located that it emanated from the north magnetic pole, trended southward through the Great Lakes region, left the American mainland near Mississippi, cut across South America to near Buenos Aires, thence through the south magnetic pole, and up in an irregular path on the other side of the earth to return to the north magnetic pole. At the present time, the North American segment of the agonic line is drifting very slowly westward.
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The only way that the two ships would have the same orientation or definition of up is if they are using a common reference system.  Astronomers use a galactic coordinate system that is based on the fact that most of the galaxies lie close to a plane.  In 1959, the galactic coordinate system was defined based on the orientation of the Milky Way creating a common "north" or "up" reference that is used to define the location of astronomical bodies.\n\nWhen we eventually get to the point that we have multiple spaceships travelling through regions of space away from reference points such as planets, there will likely be a common reference system in place that will tell the ships and their crews which way "up" is.
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The use of grid lines on maps (latitude and longitude) was first suggested by the Greek astronomer Hipparcus about 300 years before Christ. He was the first who devised a method for fixing the location of places on earth by observation of the the sun, moon and stars. He worked out the mathematics of spherical trigonometry, which allowed the results of these observations to be plotted on an earth which he knew already to be a sphere.\n\nLatitude can be found easily by measuring the height of the sun at noon. The measurement of longitude is not so simple as you need an accurate clock.
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i'm guessing supermassive blackholes, as it appears most if not all galaxies have one at the center.
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Copernicus was a Polish astronomer and mathematician who was a proponent of the view of an Earth in daily motion about its axis and in yearly motion around a stationary sun. This theory profoundly altered later workers' view of the universe, but was rejected by the Catholic church.
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Depends on how you define "middle." The center of the earth is the core, which is just short of 4000 miles down from the equator. If you're talking about the definition of "middle" in terms of the surface, then the only natural center is the Equator, which divides the southern and northern hemispheres. Since the Earth's rotation is uniform (at least in terms of unaided human scale observations), any attempt to define longitudinal hemispheres winds up being wholely artificial. The prime meridian (0 degrees longitude) is simply defined as the line that runs between the north and south poles that passes through the center of a particular telescope located at the Royal Observatory in Greenwich, England. There are historical reasons why that line was chosen, but at the end of the day, it's as good as any other one that you might choose. It's just that nowadays, it's what everyone agrees upon. So the middle of the western hemisphere is at 90 degrees west, 0 degrees latitude, which is very near the Galapagos Islands in the Pacific ocean and the middle of the Eastern hemisphere is in the middle of the Indian ocean, southeast of Sri Lanka.\n\nThe middles of the northern and southern hemispheres are the respective poles.