The unique astronomy of Istria is by far its most defining feature. Istria's solar system is binary - it orbits two suns, Chende and Atlo. This bizarre orbital pattern has an incredible important effect on the climate of Istria.
Istria orbits these suns in the shape of a figure eight, meaning that during one half of its orbit, it orbits around Chende and during the other it orbits around Atlo.
In addition, Istria orbits its suns in such a way that its axis of rotation is always pointing directly towards the center of the nearest sun, as illustrated in this diagram:
White = Istria
Yellow = Chende
Red = Atlo
Green = Istria's axis of rotation
Because of the behavior of Istria's axis as it revolves around its suns, the Northern Hemisphere (the side of Istria from which the green arrow is pointing in the diagram) will always be facing Chende when Istria is revolving around Chende, and the Southern Hemisphere will always be facing Atlo when revolving around Atlo. This has led the inhabitants of Istria to associate the Northern Hemisphere with Chende, and similarly, the Southern Hemisphere with Atlo. In fact, Istrians will often refer to a hemisphere by the name of the the name of its associated sun.
Effect on Climate
- Main article: Seasons of Istria
As one might imagine, the particular orbit of Istria has a profound effect on its climate that has shaped the history of its people since the beginning of recorded history, and continues to guide it to the present day. The most notable example of this is the Great Migration which most of the inhabitants of Istria undertake every year.
Chende is Istria's yellow sun and was formed from the spirit of Austral. A G star, Chende is important in the astronomy of Istria. It traditionally held special importance to the humans and later the tieflings, especially during the empire of Bael Turath, because Austral created the human race and because Bael Turath was largely situated on Istria's northern hemisphere under the light of Chende.
Chende was obliterated during the events of Apocalypse Eclipse.
Atlo is Istria's red sun and was formed from the spirit of Borias. An M class star, Atlo is important to the astronomy of Istria. It has traditionally held importance to the dwarves and the dragonborn, as was integral to the cosmogony of Arkhosia. Atlo is significant to the dwarves because Borias formed their race, and is significant to the dragonborn because their empire of Arkhosia ruled in the southern hemisphere under the light of Atlo.
- Anaki was turned into a cube during the events of The Hand and the Eye.
- Anaki was destroyed when Chende exploded in Apocalypse Eclipse.