From Halopedia, the Halo wiki
Sephune III is the terrestrial planet orbiting the star Sephune. The planet was the final resting place of the now destroyed UNSC Promise of Dawn, after its escape from the events of the Fall of Reach in 2552.
The planet was a Covenant world, colonized prior to the end of the Human-Covenant War. In late 2553, Jul 'Mdama's Covenant faction was using the world to gather resources and established a military foothold on the planet. This faction destroyed the original dwelling of the survivors of the Promise of Dawn at some point prior to this, forcing them to relocate. The Shipmaster in charge expressed concern that a Demon could have been drawn to the planet as a result of the destruction, but was reassured that this was not the case by his subordinate. He insisted that the humans could not find out about the nature of their work on the world. Shortly after this, the Shipmaster gave the order to destroy the human settlement and the kill the occupants, the latter effort failing due to the intervention of Linda-058.
Topography and ecology
The planet appears a dull red color from orbit, as does a large amount of the ground, which is also displayed in its plant life. There is a variety of plant life on the world, including fern-like plants, grasses and trees. Sephune III has at least one mountainous region which is covered in snow. It is unclear if the planet has large bodies of liquid water on the surface, however the presence of clouds, snow, and glacial ice suggests that there is a functioning water cycle..
List of appearances