Astrologians: What They Could Be Telling Us

[Cilia]

Ah, interesting, though I'm not aware of the this Titan/Tietan thing you're talking about.

The end boss of the Labyrinth of the Ancients is named "Titan" in Japanese, as a reference to the same endboss of the same dungeon in FFIII. It's spelled differently than the Primal "Titan," though, because katakana (I believe it's katakana; I know next to nothing about Japanese language) uses phonetic spelling, rending his name something more like "Tietan." Essentially they're able to get away with using the same name for two different characters thanks to phonemes.

Since English and most other supported languages don't do this, they renamed the LoA endboss "Acheron" as a reference to the palette-swapped version of FFIII Titan who appeared up in Syrcus Tower. Then when it was time to actually climb Syrcus Tower, lo and behold... mobs named Acheron were up there. So they had to change the LoA endboss' name again to Phlegethon. They ran into a similar hiccup with Ishgard's "astrologians." They're really just astrologers, divining the future though celestial movements. They don't have the magical capabilities of the Sharlayan Astrologians.

Exactly!
The Allagan were able to send Dalamud, which is huge, into space.
I don't see why someone like Cid couldn't make at least a small probe with its own reserve-tank of aether and launch it to space.

The Allagans sent Dalamud into space, but we don't have their technological advancement (and, by Cid's own admission, maybe never will).

Aether would probably not be a good fuel source, since it's gaseous (we think). Ceruleum might work better, but we don't know if it can function as rocket fuel and even if it can whether or not it's of a high enough grade to send a probe into space.

Either way, I don't recall video communication being available with the present technology. The Garleans have audio, and so do we though linkpearls, but even if we were able to shoot a probe into space all it would do is confirm the existence of space... which we already know exists. We also don't have the tech to send things into space; the Ixal Beastman Quests are the development of an airship that can fly higher than the clouds, so until the end of that line we can't even break the cloud ceiling. Maybe.

Even if we do have a planetary system for astrology to be based on, we can't assume anything about it since this is a fantasy setting. This world could have a geocentric model and unique laws of gravitation (or ignore gravity all together). Retrograde motion could literally happen as opposed to being just an optical illusion.

The world might have a geocentric model. This is a definite possibility.

However gravity certainly exists, probably with a similar strength to Earth's. When you jump you fall, do you not? We can't get precise measurements to determine the gravity constant, but...