George Wrote:
<<<
In 1853 there were proponents of the idea that some of the nebulae were
galaxies external to our own, but no compelling evidence for this view. At
that time it wasn't possible to resolve individual stars in M31 (Andromeda)
or other spirals and there was no way of measuring the distances to these
objects. Thus it was quite reasonable to argue, as many astronomers did,
that they were within the Milky Way. This situation continued for some
time, & there seemed to be strong arguments against the extragalactic
character of these nebulae. E.g., in ~1889 there was what we now know to be
a supernova in M31, but since astronomers didn't know about SNs they thought
it was an ordinary nova & greatly underestimated its distance. The
extragalactic character of nebulae like M31 wasn't firmly established until
the early 1920s. So on this point I'm not sure one can be too critical of
Whewell. >>>
I had always heard that also, but then I read in Whewell about the Nebula:
"It was conceived that they were not stars, but Stellar matter in the course
of formation into stars,; and it was conceived, further, that by the gradual
concentration of such matter, whirling round its centre while it
concentrated, not only stars, that is, suns, might be formed, but also
systems of planets, circling round these suns; and thus this Nebular
Hypothesis, as it has been termed, gave a ckind of theory of the origin and
formation of systems such as the solar system. But the great telescope which
Lord Rosse has constructed, and which is much more powerful than any optical
instrument yet fabricated[is was 6 feet in diameter], has been directed to
many of the nebulae, whose apearance had given rise to this theory; and the
result has been, in a great number of cases, that the nebulare are proved to
consist entirely of distict stars; and that the diffused nebulous appearance
is discovered to have been an illusion, resulting from the accumulated
light of a vast number of small stars near to each other. In this manner, we
are led to regard every nebulae, not as an imperfectly formed star or system
but as a vast multitude of stars, and, for aught we can tell, of systesm;
for the apparent smallness and nearness of these stars are, it is thought,
mere results of the vast distance at which they are placed from us." p. 12
I reassert my claim, that knowing of a impressive point of data against the
view he was advocating, he still advocated it. Indeed, he even talks about
linear wisps of nebula being resolved into stars. But then he turns around
and calls them mere dots of light and goes into his comet claim. The point
is even with today's telescopes most stars are mere points of light and all
were that way for Whewell yet he treats points of light in the galaxies
differently than points of light not in the nebula.
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