Realms of Alézun'Teran do not possess a celestial sphere in the same vein as planetary objects within Nanmir'Ath do.
Instead, they — preferably — have what is known as a Himlavalv; artifacts of power in a class all of their own, known as geographical artifacts. In colloquial terms, they are known as skies, and not all know of their true nature. Only the poorest of craftsmanships are notable to the naked human eye, as are some that are more artistical in their appearance. An ideal Himlavalv crafted by someone experienced will not look — nor feel — any different from the sky in Mésvéstell.
Nature of Himlavalvs
The nature of Himlavalvs is a debated topic among scholars. In essence, however, they are comparable to celestial spheres; also known as atmospheres. They are what exist between a realm and the vastness of the voids, provided that they are crafted well and fused with the former. Not all too different from how their contemporaries exist between planetary objects and the vastness of space, provided that the right conditions exist for their creation and continued existence.
Functions of Himlavalv
Additionally, Himlavalvs serve similar functions as atmospheres. In fact, they are justifiably considerd to be an absolute necessity if one wishes to make a realm habitable for Melathi and Nelathi species and entities.
They stave off a considerable amount of void radiation, whose reality-distorting side-effects can cause significant harm to the integrity of a realm's fabric of reality. Subsequently, they improve their integrity, allowing realms to withstand a substantial amount of strain on a metaphysical level.
Furthermore, flora has an easier time growing and producing oxygen, provided that the fabric of reality allows the process. Said oxygen is also less likely to vanish into the vastness of the voids and is instead contained within the boundaries of the realm. The same goes for the likes of other gases, such as water vapor and carbon dioxide, the latter of which allows for a greenhouse effect to commence.
Himlavalv are intangible on a physical level. Grasping at empty air is the closest Melathi may come. It is a different tale when it concerns their metaphysical structure, which can be interacted with thanks to the assistence of various artifacts of power. Certain Nelathi are also capable of this feat, as are all Selathi. Concerning the latter, Dhavians are those who are most frequently interacting with Himlavalv, either in the process of creation, to apply altercations post-creation or to repair any damage it may have recived.
A Himlavalv has one of two metaphysical semblances; as a silky fabric that is either stretched taut or is hanging loose, or as a crystalline sheet that is as rough as a cave ceiling, or as smooth as a glass dome. This is dependable on whoever crafted it and the amount of time and effort spent on its creation.
One cannot determine the state of the Himlavalv on its semblance alone; the fabric may be durable and elastic enough to withstand a substantial amount of strain, while a crystalline sheet may be as brittle as a ceramic cup.
While all Selathi are capable of perciving the metaphysical semblance of a Himlavalv, only a select few Nelathi are capable of it. And Melathi may as well be blind, unless one has access to artifacts of power that allow for it.
Width and height
The width of a Himlavalv is entirely dependable on the size of the realm it is fused to. The height of a Himlavalv is more interchangeable, although the baseline is approximately a hundred kilometers. Dependable on the preferences and skills of the creator, the height may range from large, immense, or nigh-infinite. There has been some debate on whether or not to designate the latter their own realms, though it has gained little traction.
Reaching the end
As per their nature, Himlavalvs have an definitive end. But what exist at that end varies between instances, and what one experience — and sees — is dependable on wheter one is a Melathi or Selathi. Nelathi may experience either, depending on their metaphysical makeup.
If one is a Melathi
Melathi are most likely to never truly come into contact with the end of the Himlavalv. Instead, they are seamlessly pulled backward indefinitely, no matter how fast they fly, provided that the Himlavalv was made properly.
This effect can be overcome with the correct artifact of power, although should they reach the true end without proper protection, they will nigh-instantly vaporize due to the high concentration of energy the Himlavalv consists out of. Similar to how one would fare if one came into contact with an immensely high voltage fence without isolation.
If one is a Selathi
Selathi — or those with the proper artifacts of power — are able to touch and see the end of the Himlavalv. The most common descriptor is that of a wet or damp reflective surface that irregularly showcases illusionary capillary waves.
If the surface is distrubed, no capillary waves will manifest, and what one will find on the other side is either cold crystal or a silky smooth fabric that has a faint electrical charge to it.
Himlavals are essentially vast artworks and particularly the Dhavians have a tendency to take great pride in their crafts. Each Himlavalv is thus unique in its appearance, even if there might be difficult to discern any initial differences. The best kind of artwork is argued to be those that are ever-changing, similar to a natural sky. Although there does exist some beautiful static Himlavalvs as well, most of which depict starry skies or dusks.
What may enhance an Himlavalv further is the application of Solis Rings and Lunais Crescents, as they divide it in a day and night cycle if properly crafted and configured.
What does it look like if there exists no Himlavalv and the realm is open to the vastness of the voids? A faint approximation of an atmosphere will manifest. This is an automatic reaction by a properly made fabric of reality that Dhavians have no control over.
A standard atmosphere has a faint luminescent bluish-white shade to it and a height of roughly seventy kilometers. The air of the realm is thin if it exists at all and sprinkled with tiny grains of suspended ice. Beyond that, a cold, pitch-black space opens up and spews out reality-distorting radiation. An intermitted unknown sound resonate from this opening, which they describe as shrieking, and it can be heard whether one is deaf or not.