Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: copernicus1234 on 06/05/2014 22:21:10
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I was thinking and I came up with this odd vision. In this vision, it was stated, to me that the stars in the universe, including our sun, are stationary, based on experimental measurements. Example, a photograph of the celestial universe, in the last ten years, there have not been a measureable change in the positions of the stars. Probably in the last 100 years, since photograph, there hasn't been any changes of position, of the stars, and 1000 years there is no evidence (photography) and the time problem (no clocks). Isn't the assumed motion of the stars in the universe caused by the earth's daily and yearly rotational motions? Can someone explain to me how the distances of the stars, not including the sun, is measured. This in a very perplexing problem that has keep me awake, at night. Thank you. Also, all the movies suchas Star Wars and Burn-e represent a celestial universe that is stationary. Did you see Pesto? with the rabbit. how cute.
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I think the stars do slowly move, but you're right, it may be slower than can be easily determined using a century or so of photographic evidence. Hand drawn star charts may not have the accuracy required to determine star position through a few past centuries, but may be useful for observing closer phenomena such as planets and comets, or perhaps some of the nearest stars.
One very powerful tool is redshift/blueshift. Essentially various chemicals create a very specific band pattern of the light spectrum which one assumes should be universal everywhere. However, there are variations in these spectrum bands. When a star is approaching us, the frequency gets shorter, or blue shifted due to the speed differential. When a star is receding from us, the frequency gets longer, or red shifted.
This redshift/blueshift then gives us the relative velocity of stars around us.
What was found is that the more distant stars all tend to be redshifted indicating that they are receding from us, and the amount of redshift is related to the distance. Sorry, I don't have the specifics on how the actual distances are determined.
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I'm not sure about the "stationary" universe with Star Wars and Star Trek.
There are many "errors", and they don't necessarily show very good orbital dynamics or perspective. Since many objects move together, distances would be relatively stable, and should be able to be easily compensated by computers.
In fact, the future projections of our actual Voyager and Pioneer probes must include calculations of the movement of the stars over the next few million years.
Back to Star Trek, distances are always a bit hard to understand. When one sees the Zefram Cochrane ship hit "warp speed", it shows what appear to be stars flying by. Yet, after a few moments, they turn around and see Earth in the distance (which wouldn't be possible if they had passed other stars).
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CliffordK................."One very powerful tool is redshift/blueshift. Essentially various chemicals create a very specific band pattern of the light spectrum which one assumes should be universal everywhere. However, there are variations in these spectrum bands. When a star is approaching us, the frequency gets shorter, or blue shifted due to the speed differential. When a star is receding from us, the frequency gets longer, or red shifted."
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The red/blue shift is produced by the earth's daily and earth motions, not the motion of the stars.
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It is true that the annual orbit of the Earth around the Sun results in a parallax shift between closer stars and more distant stars. This effect has been used to measure the distance to closer stars (...after it was used to show that the Earth orbits around the Sun). But after a year, the stars are back to their original positions - or would be if they had no "Proper Motion".
Sir Edmund Halley identified that several stars had shifted positions across the sky when he examined an ancient Greek star map. The positions of certain stars were so different that no accomplished astronomer like Hipparcos could get it so wrong. We now know that these stars are close to the Sun (compared to most stars in our galaxy), and so they appear to move more rapidly across the sky, independent of the rotation of the Earth around its axis, or rotation around the Sun.
See: http://en.wikipedia.org/wiki/Proper_motion#Stars_with_high_proper_motion
Just as the Sun's gravity causes the Earth to orbit the Sun, the Milky Way's gravity causes the Sun and other stars to orbit the Galaxy. These stars move across the sky at different rates, just as the planets in our solar system move across the sky at different rates (but the planets just appear to move a lot quicker because they are much closer). If these stars were not orbiting the galaxy, but were stationary in space, this would only be a temporary event, as they would all immediately accelerate towards a growing black hole at the center of the galaxy.
The Hipparcos satellite (http://en.wikipedia.org/wiki/Hipparcos) measured the parallax and proper motions of 100 thousand stars; the current Gaia mission (http://en.wikipedia.org/wiki/Gaia_(spacecraft)) is planned to measure about 1 billion stars
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There are plenty of binary star systems where the stars can be seen to orbit each other, and stars have been seen to move as they orbit the central galactic black hole (http://www.astro.ucla.edu/~ghezgroup/gc/pictures/orbitsMovie.shtml), so movement can be observed in human timescales.