# Was the sun assumed to be at rest aether frame?

Back in the past, was the sun assumed to be at rest in the luminous aether frame?

• How long ago is "was", please? In any case, what research have you done? For much of history, the Sun was assumed to be moving round the Earth… not "at rest" in any frame. For a little while, the Sun was taken to be a body at rest, with all else in the solar system rotating around it. In recent centuries, the Sun has been clearly seen as moving with respect to everything else and still, apparently, the resting point around which all else in the system rotates. Which works for you? – Robbie Goodwin Feb 25 at 21:39

Not necessarily. They did not know the velocity of the Sun with respect to aether. What they tried to do is to measure the speed of the Earth with respect to aether. If any velocity were detected, one could infer the speed of the Sun. But no speed was detected. And the idea that the Earth is at rest while everything else moves looked absolutely implausible in 19th century.

• Hi Sir Alexandre, My textbook Kleppner, uses the value of $v$ , the average orbital speed of Earth round the sun as the speed of Earth thorough ether in the Michelson morley experiment. So I think back then they thought that the sun might be at rest in the ether. – Kashmiri Feb 25 at 14:41
• Does the author of that textbook have a historical note about that calculation? I suspect not. Just because they do the calculation that way in that specific textbook (i.e. assume the Sun is at rest w.r.t. the aether), does not imply that is how the calculation was done "in the past." – Daddy Kropotkin Feb 25 at 21:49
• The book is highly reputable from MIT, Although they have not added much historical notes about it. That made me ask this question. – Kashmiri Feb 26 at 4:25

19th centry astronomers believed that the Sun and the Solar System revolved around the central point of the Milky Way Galaxy. Thus 19th centry physicists should have believed that the Sun moved with respect to the aether.

By the beginning of the 19th century, astronomers were certain that the Sun was a star in the Milky Way Galaxy, which most astronomers assumed was the entire universe, though there were speculations that other galaxies might exist beyond the Milky Way.

According to Newton's law of gravity all objects in the Milky Way Galaxy must revolve around the barycenter, the mathematical center of mass, of the Milky Way Galaxy.

Star Names: Their Lore and Meaning Richard Hincley Allen, 1899, 1963, The section on constellation Hercules - star Lambda Heruclis says:

Athough Johann Tobias Mayer of Gottingen seems to have been the pioneer, in 1760, in the efforts to ascertain the direction of the sun's movement among the stars, yet Sir William Herschell was thes first successful investigator as to this, about 1806, and he settled upon the vicinity of Lambda as the objective point of our solar system, the Apex of the Sun's Way; and his determination was, in a great measure, confirmed by later astronomers.

And Wikpedia says:

In 1783, English-German astronomer William Herschel described the solar apex, the point in sky towards which the Solar System is moving; using data from double stars, he identified this position as close to Lambda Herculis. Today it is known the solar apex is not so close to this star, however it is only 10° away from the position currently accepted (in Hercules, southwest of Vega).[14][15][16]

https://en.wikipedia.org/wiki/Lambda_Herculis[1]

Astronomers knew that the distances between one star and its nearest neighbor must be immense, to say nothing of the distance from one one edge of the Milky Way Galaxy accross the center point to the opposite edge. But they didn't know what the scale of interstellar space was until the distances to three stars were measured in the late 1830s and the distances to several more were measured in following decades.

I happen to own an astronomy book written by Ormsby M. Mitchell (1810-1862),The Planetary and Stellar Worlds, 1851.

https://en.wikipedia.org/wiki/Ormsby_M._Mitchel[2]

Lecture X the Motions and Revolutions of the Fixed Stars, pages 318-319, describes Madler's theory that Alcyone in the Pleiades star cluster is the central sun at the center of gravity of the Milky Way Galaxy (then assumed to be the entire universe).

After a profund examination, Madler reached the conclusion that Alcyone, the principal star in the group of the Pleiades, now occupies the centre of gravity, and is at present the sun about which the universe of stars comprising our central system are all revolving.

Star Names: Their Lore and Meaning Richard Hincley Allen, 1899, 1963, the section on Canis Major - Sirius says:

The celebrated Kant thught that Sirius was the central sun of the Milky Way;...

If Sirus was the central sun, other stars would revolve around it. Emmanuel Kant lived from 1724 to 1804.

Star Names: Their Lore and Meaning Richard Hincley Allen, 1899, 1963, the section on Taurus - The Pleidades - Alcyone says:

Madler located in Alcyone the center of the universe, but his theory has been shown to be fallacius. There is no satisfactory reason for his conclusions, and little more for Miss Clerke's remarks about the probable size and distance of Alcyone,--that it shines to its fellow stars with a luster eighty three times that of Sirius in terrestrial skies, while its intrinsic briliancy, as compared with that of the sun is 1000 times greater. All this rests upon the extremely doubtful assumption of a parallax of 0".013 deduced from the star's proper motion.

If Alcyone was in the center of the universe all the other stars would have to revolve around it.

Actually Alcyone is even farther than Miss Clerke said, since it now listed as having about 2,400 times the luminosity of the Sun.

https://en.wikipedia.org/wiki/Alcyone_(star)[3]

At the present time the Sun is believed to orbit the gravitational center of the Milky Way Galaxy in a roughly circular orbit at a distance of about 27,140 plus or minus 460 light years from the central point.

It takes the Solar System about 240 million years to complete one orbit of the Milky Way (a galactic year),[16] so the Sun is thought to have completed 18–20 orbits during its lifetime and 1/1250 of a revolution since the origin of humans.

https://en.wikipedia.org/wiki/Milky_Way#Sun's_location_and_neighborhood[4]

If the Sun has an perfectly circular orbit of exactly 27,140 light years radius, and thus exactly 185,415.052 light years circumference, and it takes exactly 240,000,000 years to make one orbit, the line between the Sun and the center of the Galaxy would change its angle very slightly during any time period which is understandable by humans.

There are 360 degrees of arc in a full circle, so it would take 666,666.666 years for the angle to the Sun to move by one degree as seen from the galaxtic center.

There are 60 minutes of arc in a degree, so it would take 11,111.1111 years for the angle to the Sun to move by one minute as seen from the galactic center.

There are 60 seconds of arc in a minute of arc, so it would take 185.185 years for the angle to the Sun to move by one second as seen from the galactic center.

In Edgar Allan Poe's story "Mellonta Tauta" (1849), a journel written in the year 2848, it is said: