Stellar Mass and size

[whulorigan]

... 13th magnitude.

I don't know what the lack of electrical lights would have had on seeing back then.

I have been out where the only lights were flashlights, no LED ones back when I was a kid, and star seeing was very good.

A (good) human eye can discern down to about 6th magnitude. All of the stars that come down to us from antiquity are at least that bright or brighter. Uranus is about 5.5 or so, and is just barely visible to the naked eye if you know where to look and have good eyes.

13th magnitude is 7 orders of magnitude too dim to be seen by the naked eye (good or otherwise).

edit: isn't Uranus or Neptune on its side ? I don't remember what astronomers have said did that.

Neptune's rotational axis is tilted by about 28^o relative to its orbital plane. Uranus's is tilted by about 98^o (it effectively "rolls" thru its orbit).

 

[JimMarn]

I didn't think 13th magnitude would be seeable with just the human eye. I know some star clusters and double stars are a test of eyesight, but they would have to be mag 6 or brighter as you point out.