orthogon wrote: Lothario O'Leary wrote:
speising wrote:yeah, it's a stupid convention.
just about every sf book since ever has numbered planets with roman numerals from I (Sol III), why didn't astromomers adopt that sensible notation?
Now I'm wondering what would Earth be called under the astronomical exoplanet convention, assuming Sol for the star.
If all the planets are considered to be discovered at the same time, probably Sol d; in realistic order of discovery... probably either Sol f or Sol g, after Jupiter, Saturn, Neptune, Uranus, and possibly Venus, probably in that order.
I was trying to work out your order, but I now realise you probably mean "realistic order of discovery by observers from another solar system
". I was trying to figure out the actual
historical order of discovery by humans -- I thought you were positing that in a sense Venus and Mars were discovered before Earth, in that they were identified as celestial bodies by proto-astronomers before Earth itself was recognised as being the same type of thing as them.
I didn't even think of that
possibility. I was, indeed, considering a "realistic" order of discovery if Earth was an exoplanet
(i.e. from another solar system).
Soupspoon wrote:I was thinking that "Sol b" would have been the Moon (later deprecated), at first (c-g being one order or other of the five other pre-George's Star 'discoveries').
But then I realised that it would maybe be "Terra c" (assuming b being Sol, maybe verse-vica if otherwise) until shown otherwise.
I'd say it probably went like this: Sun and Moon (likely, but not certainly, in that order), Mars (obvious color), Jupiter, Venus (it took a while to figure out it wasn't two
celestial bodies), Mercury (inconvenient to observe); then eventually Earth joined the list, and it stayed stable until the discovery of Georgium Sidus.
This means that, as of just before Earth would have joined the list, the numbering would've been Terra b-g for Sun and Moon, Mars, Jupiter, Venus and Mercury respectively.
When Earth does join the list, things depend on which description we use (Ptolemaic, Copernician, Tychonic, or one of the weird versions from the early heliocentrists).
Assuming a straight switch from Ptolemaic to Copernician, we probably
would've, theoretically, ended up with either Sol b-e (renumbered) or Sol d-g (keeping the numbers) for Mars, Jupiter, Venus and Mercury.
In the former case Earth is straightforwardly Sol f (Georgium Sidus/Uranus is Sol g, Ceres is Sol h, and it gets messy after that); in the latter case, Earth is probably
Sol h (but could in principle also end up as Sol b).