Earth has been long abandoned due to its toxic atmosphere. It is now overgrown with mutated jungle structures that have devoured most of the prior signs of civilization. Infestation and roaming wildlife still inhabit its surface but anything of value was stripped by scavengers generations ago.
Earth is a planet under Grineer control, and is the first planet players can access. It is linked through junctions to Mars and Venus. Lua, the Earth's moon, becomes accessible from Earth (without a junction) after players complete the quest The Second Dream.
Earth is the only planet to feature the Grineer ForestTileset. Every four hours, the forest tileset will change from day to night, mimicking the day cycles in real life. The change will feature different vegetation that can be scanned for extracts that are used to craft Antitoxins, Apothics and medical regeneration packs, with Sunlight variants during the day and Moonlight variants at night.
Various geological events and formations pertaining to Earth (Lith, Cambria, Mantle).
The personification of the Earth in Greek Mythology (Gaia).
Despite being previously described as a "desolate, ruined world" Earth has very lush forests, which Vay Hek tried to destroy during The Cicero Crisis. This original description is probably no longer canon.
This also means that Earth is the earliest place for Kubrow mods to be obtained.
Earth seems to have the largest variety of enemy levels in the game, with most missions being at levels 1-8, Vay Hek's Assassination at 20-25, and The Law of Retribution being at levels 70-80.
Earth is the first and only planet to have a day-night cycle, which changes every 4 hours (12, 4, 8 am and pm eastern American time) with the exception of its Dark Sector nodes, Coba and Tikal, which remain in the dark.