Spiral Nebula in Andromeda viewed edgewise
Taken with 60-inch Reflector of the Mt. Wilson Observatory
Not more than a generation ago a survival of the old idea of a fixed center was seen in the belief that Alcyone, in the Pleiades was a "central sun" about which all the stars revolved. It is now well known that the Pleiades form a moving star cluster. Alcyone is therefore drifting slowly onward through the universe and the idea of a fixed and immovable center to which man may anchor his ideas is drifting away also. There are, it is true, local centers of systems, such, for instance, as the sun occupies in the solar system or some group of stars may occupy in the stellar system to which our sun belongs, yet as a whole these systems move on and their centers with them. There is no evidence today that any absolutely immovable point exists in the heavens.
No celestial object has been found to be without the attribute of motion, not only motion onward through the universe, but also rotational motion about an axis of the body. The planets rotate on their axes as well as revolve about the sun, and the sun also turns on its axis as it moves onward through space. This rotational motion is also found in the nebulæ and star clusters as well as in the stars and planets. No object in the heavens is known to be without it. Even the slowly drifting Orion nebula possesses a rapid internal velocity of rotation. There is no such thing as a body absolutely at rest in the universe.
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TABLE
Showing the number and relative size, velocity and distribution of the various types of celestial objects.
