Starship Asterisk*

Joe Stieber wrote: ↑Fri Jun 25, 2021 4:37 am Of course, M31's satellite galaxies, M32 and M110, are also present in the picture. M110 floats above M31 while M32 is like a puffy star below-right of M31's core. There's another galaxy too, NGC 404, the "Ghost of Mirach," which is a faint smudge just above the bright star Mirach (Beta Andromedae) to the right of the chimney near the bottom.

NCTom wrote: ↑Fri Jun 25, 2021 12:30 pm What was the duration of this single exposure and where would I need to look for that information?

• Henry IV, Part I [Act II, scene 1]

• Heigh-ho! an it be not four by the day, I'll be
  hanged: Charles' wain is over the new chimney,
  and yet our horse not packed. What, ostler!

JohnD wrote: ↑Fri Jun 25, 2021 12:10 pm
What do you mean, EM? That Andromeda should have been bigger in the sky? That would have screwed up the Milky Way, which it will do, one day in the future, as we rush towards it! It's the only galaxy that's naked eye visible, and was known when the Ptolomeic model of the Universe reigned, but as a 'nebula', a cloud.

https://en.wikipedia.org/wiki/Magellanic_Clouds#History wrote:
<<The Magellanic Clouds (or Nubeculae Magellani) are two irregular dwarf galaxies visible in the Southern Celestial Hemisphere. The Magellanic Clouds have been known since ancient times by indigenous people from South America and Africa, and from the first millennium in Western Asia. The first preserved mention of the Large Magellanic Cloud is believed to be in petroglyphs and rock drawings found in Chile. They may be the objects mentioned by the polymath Ibn Qutaybah (d. 889 CE), in his book on Al-Anwā̵’ (stations of the Moon in pre-Islamic Arabian culture).Later Al Sufi, a professional astronomer, in 964 CE, in his Book of Fixed Stars, mentioned the same quote, but with a different spelling. Under Argo Navis, he quoted that "unnamed others have claimed that beneath Canopus there are two stars known as the 'feet of Canopus', and beneath those there are bright white stars that are unseen in Iraq nor Najd, and that the inhabitants of Tihama call them al-Baqar [cows], and Ptolemy did not mention any of this so we [Al-Sufi] do not know if this is true or false." Both Ibn Qutaybah and Al-Sufi were probably quoting from the former's contemporary (and compatriot) and famed scientist Abu Hanifa Dinawari's mostly lost work on Anwaa. Abu Hanifa was probably quoting earlier sources, which may be just travelers stories, and hence Al-Sufi's comments about their veracity.>>

Eclectic Man wrote: ↑Fri Jun 25, 2021 11:11 am I wonder how different Western history would have been had Andromeda been easily visible in the sky when the Roman Catholic Church decided that the whole of creation orbited the Earth. It would have been obvious that Andromeda was a system all of itself.

Chris Peterson wrote: ↑Fri Jun 25, 2021 2:27 pm

Eclectic Man wrote: ↑Fri Jun 25, 2021 11:11 am
I wonder how different Western history would have been had Andromeda been easily visible in the sky when the Roman Catholic Church decided that the whole of creation orbited the Earth. It would have been obvious that Andromeda was a system all of itself.

If we were closer to Andromeda, it would be bigger. But no brighter. The spiral structure would still be largely invisible to the eyes. It would look like a blob sticking off of the northern Milky Way, and about the same brightness as the Milky Way. There would be nothing to give away its actual size or its actual distance. Just another fuzzy gray thing in the sky.

https://en.wikipedia.org/wiki/Tycho_Brahe wrote:

In this depiction of the Tychonic system, the objects on blue orbits (the Moon and the Sun) revolve around the Earth. The objects on orange orbits (Mercury, Venus, Mars, Jupiter, and Saturn) revolve around the Sun. Around all is a sphere of fixed stars.

---

<<Tycho Brahe (14 December 1546 – 24 October 1601) aspired to a level of accuracy in his estimated positions of celestial bodies of being consistently within an arcminute of their real celestial locations, and also claimed to have achieved this level. But, in fact, many of the stellar positions in his star catalogues were less accurate than that. The median errors for the stellar positions in his final published catalog were about 1.5', indicating that only half of the entries were more accurate than that, with an overall mean error in each coordinate of around 2'. Although the stellar observations as recorded in his observational logs were more accurate, varying from 32.3" to 48.8" for different instruments, systematic errors of as much as 3' were introduced into some of the stellar positions Tycho published in his star catalog — due, for instance, to his application of an erroneous ancient value of parallax and his neglect of polestar refraction Incorrect transcription in the final published star catalogue, by scribes in Tycho's employ, was the source of even larger errors, sometimes by many degrees.>>

neufer wrote: ↑Fri Jun 25, 2021 4:29 pm

Chris Peterson wrote: ↑Fri Jun 25, 2021 2:27 pm

Eclectic Man wrote: ↑Fri Jun 25, 2021 11:11 am
I wonder how different Western history would have been had Andromeda been easily visible in the sky when the Roman Catholic Church decided that the whole of creation orbited the Earth. It would have been obvious that Andromeda was a system all of itself.

If we were closer to Andromeda, it would be bigger. But no brighter. The spiral structure would still be largely invisible to the eyes. It would look like a blob sticking off of the northern Milky Way, and about the same brightness as the Milky Way. There would be nothing to give away its actual size or its actual distance. Just another fuzzy gray thing in the sky.

It might have helped if Sirius (distance = 2.64 pc) were a hundred times closer (~0.02 pc) so that Tycho Brahe might have detected an annual parallax in sync with the "Sun's orbit".

Chris Peterson wrote: ↑Fri Jun 25, 2021 5:03 pm

neufer wrote: ↑Fri Jun 25, 2021 4:29 pm
It might have helped if Sirius (distance = 2.64 pc) were a hundred times closer (~0.02 pc) so that Tycho Brahe might have detected an annual parallax in sync with the "Sun's orbit".

Except at that distance Sirius would be inside our own Solar System, and there would be no planets with stable orbits. So there would be no Brahe to have detected it.

Sirius:
Radial velocity (Rv)	−5.50 km/s
Proper motion (μ)	RA: −1.44 Parallax/yr
Proper motion (μ)	Dec.: −3.23 Parallax/yr

Eclectic Man wrote: ↑Fri Jun 25, 2021 11:11 am I wonder how different Western history would have been had Andromeda been easily visible in the sky when the Roman Catholic Church decided that the whole of creation orbited the Earth. It would have been obvious that Andromeda was a system all of itself.