"The sky is so high, so far. So we dream of it."
The few scholars of Filgaia with the time to think of something so lofty as the heavens break the world into three: The Sea of Sand that is the earthly Filgaia; the Sea of Wind that is its open sky; and above them all, shining unchanging no matter how dire Filgaia's state may become, the great Sea of Stars.
Above the sky, but below the stars, in what few today know to call 'orbit', are some of this dying world's greatest mysteries.
Filgaia is a planet with two moons. The larger and nearer of these celestial companions is the Old Moon; the second, farther and smaller yet nonetheless too large to be a star, is called the New Moon.
The Old Moon looms larger in the sky than Earth's moon, but appears just as devoid of life from Filgaia's surface. Its orbits have long since been marked and measured, and Filgaia's navigators, be they men of the sea or of the soil, know that the Old Moon will always guide them well. To Guardianists it is held as the domain of Celesdue, the Moon Guardian. To all, it is a trustworthy beacon in the night. The Filgaians have no idea of the Old Moon's secrets, not even its name: 'Lunar' is an unfamiliar term to the people of Filgaia.
The New Moon is small in the sky, often little more than a distant, glimmering light. Yet, those who make a study of such things know that no star could be so bright nor so constant. The scholars in Sielje Region, with their telescopes and unimpeded view of the stars, claim that the object is man-made; that ancient Filgaians made it, long ago when such a thing as building a kingdom in the Sea of Stars would have been no remarkable feat. The smallfolk can't imagine such a mad idea, but it is the source of the object's name, and it did hurt its reputation: Now, the navigators of Filgaia fear the New Moon, believing it to be a lost, Demonic thing whose wandering path across the sky will lead a traveler into peril...or worse.
Other objects sprinkle Filgaia's near orbits. Filgaians know nothing of them except that their movements are predictable, but strange; some faster than normal stars, others slower, some seemingly static from any point in the world. Some are large and some are small. Drifters, through strange accidents, have occasionally returned with stories of Elw temples that they swear could only have been off in the Sea of Stars, but then Drifters always have such fantastic tales to tell.
Those marooned on Filgaia from space might well know enough about the science of orbit to place these objects as satellites, or maybe even larger orbital objects. That such achievements would be entirely beyond Filgaia as it is now only begs deeper questions, questions whose answers must lie somewhere below the spreading sands.
The Silver Star of Lunar is what Filgaians call the Old Moon. It is surely artifice from Althena that conceals the Silver Star's true nature from the people of the Blue Star, and her reasons for doing so remain a mystery.
The satellites and space stations and other strange structures that thread the distance between Lunar and Filgaia are visible from Lunar as well, and quite obviously sit between the two bodies. Lunarians can only guess at what they might be, and most of those guesses involve the machinations of the Vile Tribe. In Spira, such accusations usually land on the heads of the Al Bhed; the Al Bhed, who have long since learned that a certain minimum of mystique can be a survival aid, let the Yevonites believe what they will, but have only a little more idea of what those strange glimmers could be.
The massive body the Filgaians call the New Moon is likewise an occasional visitor to Lunar's sky. The uncanny appearance of Filgaia's second moon - more visibly strange so much closer to it - has led to a number of fanciful stories among the creative bards of Lunar's taverns, but the most common name for it is the Black Star. The Black Star is held as the vilest of ill tidings: A home to creatures so terrible the Goddess Althena banished them from Silver and Blue Stars both, entirely, and forever. To have the Black Star shining upon your path is to be walking into the arms of Althena's most hateful enemies.
The Black Star is associated with a phenomena known as the "Scarlet Night" on Lunar. When the Blue Star obscures the light of the sun, painting all of Lunar in red light, the Black Star is easily the most prominent object in the sky. The Scarlet Night is a time of terror, when it is said great sins unfold and death is never far away.
The rest of the solar system
The system to which Filgaia belongs has five known planets total. Filgaia is the fifth and seemingly the outermost one. The others orbit fairly closely to the system's star. According to astronomers, there is a good-sized gap between Filgaia and the innermost planets.
On Filgaia, the four inner planets are known, from innermost to outermost, as Luceid, Raftina, Justine, and Zephyr. Zephyr in particular is a bright planet, brighter than even its relative closeness to Filgaia would predict. In many respects it's similar to Venus in brightness and plays a similar role of the morning/evening star.
According to the observatory at Sielje, there is something called an asteroid belt between Zephyr and Filgaia. This consists of a wide field of irregularly-shaped rocky objects. These -- and the belt as a whole -- cannot be seen without a strong telescope (such as the one Sielje has). Certain other entities may be able to independently confirm the existence of the asteroid belt (but may not be taking part in the discussion for various reasons).
The belt cannot be seen from Lunar as they lack the necessary technology.
The planets meanwhile are visible from Lunar, and Meribia and Glenwood have their own names for them. The planets are named for the Four Dragons: as these roles may change, they bear the names of the previous Dragons. Colloquially they are often referred to as 'the White Dragon Star' or the 'Red Dragon Star'.
Currently they are named from innermost to outermost: Quark ('White Dragon Star'), Cyan ('Blue Dragon Star'), Rubeus ('Black Dragon Star'), and Amelia ('Red Dragon Star').
Spira has its own names for the planets as well, mostly reflecting Summoners. In order (innermost to outermost) they are: Yocun, Ohalland, Gandof... and Gilgamesh. Nobody knows why it's called Gilgamesh.