Ersark's geography is comprised mostly of rocky, irradiated wastelands. The two main continents, Garthur and Reidabond, are equally as inhospitable. The most striking geographic feature on the planet is the Sorich Crater, which is a relic from a nuclear war on the planet (specifically one of the nukes in the war that destroyed the atmosphere). The crater is more than 400 km in diameter, making it more than twice as large as the Chicxulub crater on Earth.
Little is known of Ersark's climate prior to the fall, but it can be assumed that the planet in general was temperate, if a little dry. Now, however, Ersark's climate is usually hot and humid (and said humidity usually comes from acid rain, which falls on the planet near-constantly now). The very atmosphere is poisonous, with acid and radiation polluting the once vibrant planet.
Almost all of Ersark's native plant and animal life went extinct when Ersark's biosphere broke down after the fall. Nowadays, the most common non-Sarken life on Ersark are genetically altered creatures brought over from other worlds. Giant cockroaches, enhanced from cockroaches brought over from Earth, make up one of the most common species on the planet, replacing the extinct gaggerpach beetles that made up a large part of the original Sarken diet.
Despite the inhospitable atmosphere, Ersark is densely populated. Its cities are sprawling, much larger than the cities of Earth, with factories constantly spewing out more toxic chemicals into the atmosphere and the oceans, polluting the land even more. The most populous city on Ersark is the capital city Ulderkel, which has a population of 430 million people.
Of the 7 billion people that live on Ersark, only 3 billion of them are sarken. Kakkons make up the next biggest minority, at 2 billion. 1 billion of the remaining individuals are loyalist volun, while raijalresh, airoth and qualls make up less than 500 million.
Ersark's moon, Kose, is a selenitic moon that is widely populated much like Ersark itself. The moon is also just as polluted as Ersark, with its formerly barren climate Ersaformed to resemble its mother planet. It alone is home to 2 billion colonists, making it one of the most populous Sarken colony worlds in the Hegemony.