Civilization VII: Earthrise will let players explore and colonize celestial bodies, but those planets will not have hex maps for placing individual cities, buildings or improvements. Creative director Ed Beach makes that distinction in Firaxis' September 23 developer Q&A.

Exploration uses human and rover missions to planets, moons and asteroids, with resources and future colony locations among the objectives. The team describes solar-system exploration through roughly 2050 as its frame of reference.

Cities and districts on Civilization VII’s main world map
The main Civilization VII map. Firaxis says Earthrise’s Planetarium will not use this kind of individual city and building placement.Firaxis Games / 2K

The Planetarium is an abstract solar-system view

Players can open a planet to inspect its characteristics and moons, and see which competitors have started exploring or colonizing there. Beach describes a more abstract system than the main game map.

Hex-based planetary maps are discussed as a possible future direction, not a promised Earthrise feature.

The Earthrise announcement places the paid expansion in 2027 without an exact release date. If off-world city construction is the feature you want, wait for further demonstrations: the confirmed Planetarium does not provide that kind of building placement.