Belus is a searing hot world with temperatures rising well over 500 c. However temperatures can drop to below -162 c on the side facing away from the sun. The planet's terrain is extremely rugged, pot-marked by craters which have chipped away large portions of the surface. It is hinted that a wreckages of unknown origin pre-dating the Forerunners are situated at the bottom of these craters though ONI has kept this highly classified.