Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Vorador on 18/10/2013 09:47:39
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Hello everyone,
Stellar aberration is taken as one of the strongest observational evidence for heliocentric model of the solar system. I wanted to know why this phenomenon can not be explained by the geocentric model (since it is caused by relative motion of stars and earth)?
Thank you! :)
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The direction and magnitude of stellar aberration is determined by:
- the rotation speed of the Earth at the place of the observer (diurnal aberration)
- the speed of the Earth relative to the Solar System (annual aberration)
- the speed of the Solar System relative to the Milky Way (secular aberration)
In other words: the direction and magnitude of stellar aberration is not determined by the motion relative to the observed stars but to the motion relative to Solar System, Milky Way, ... . The annual aberration for any star in a given direction is the same, independent of the motion of the observed star.
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In the days when the structure of the solar system was in hot dispute, it was thought that the stars were unmoving and unchanging*, all at the same distance (http://en.wikipedia.org/wiki/Flammarion_engraving). So they would have expected no motion from the stars.
So the observation of stellar aberration (http://en.wikipedia.org/wiki/Aberration_of_light) that light from the stars appeared at a slightly different angle on a yearly cycle indicated that the Earth was moving around the Sun every year; the Earth was not stationary at the center of the universe, with the Sun orbiting around the Earth every day.
*Some known exceptions included the star Algol (http://en.wikipedia.org/wiki/Algol), "the ghoul", a short-term eclipsing binary; and the occasional appearance of a Nova (meaning "new star", but we now know it represents the death of a star).
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In the days when the structure of the solar system was in hot dispute, it was thought that the stars were unmoving and unchanging*, all at the same distance (http://en.wikipedia.org/wiki/Flammarion_engraving). So they would have expected no motion from the stars.
So the observation of stellar aberration (http://en.wikipedia.org/wiki/Aberration_of_light) that light from the stars appeared at a slightly different angle on a yearly cycle indicated that the Earth was moving around the Sun every year; the Earth was not stationary at the center of the universe, with the Sun orbiting around the Earth every day.
*Some known exceptions included the star Algol (http://en.wikipedia.org/wiki/Algol), "the ghoul", a short-term eclipsing binary; and the occasional appearance of a Nova (meaning "new star", but we now know it represents the death of a star).
I see. So stellar aberration alone isn't evidence enough that earth circles the sun.
Thank you for your answers and sorry for such a late response.