Space games and apps that use real astronomy

Almost every space game invents its universe, and there is nothing wrong with that. But a smaller number of apps are built on the real one: the actual sky over the phone, the actual physics of getting to orbit, the actual planets and their actual distances. For some people that is the whole appeal. The thing on the screen is out there.

This is a list of those, with a note on what in each is real and what is not, because none of them is entirely one or the other.

The sky itself

• Stellarium Mobile. A planetarium: hold the phone up and it shows what is behind it, to the star, for any time and place. The catalogue is the real one, the same data professional software uses. Nothing is invented. Free, with a paid version for the deep catalogue.
• Sky Guide. The same idea with more polish and a gentler tone, and with satellites and the space station drawn in as they pass. Real sky, real positions, real time. Paid, once, with a subscription for extras.
• NASA's Eyes. Not a game and barely an app: a viewer for where every active mission is right now, in real orbits, from the agency that flies them. It is the closest thing to looking out of the window. Free.

The physics

• Spaceflight Simulator. Build a rocket out of parts and try to get it into orbit, land on the Moon, or reach Mars. The planets are a scaled-down version of the real solar system, but the orbital mechanics are real, and it teaches the one thing about spaceflight that no film does: that getting to orbit is about going sideways. Free with purchases.
• TerraGenesis. Terraform Mars, Venus, the Moon and a handful of others. The starting conditions of each world are drawn from the real numbers, temperature, pressure and the rest, and the changes follow from them. The timescales and the economy are invented. Free with purchases.

The places

• Voyage. A ship travels from Earth to somewhere real and waits there until the app is opened. Every destination is an actual object or phenomenon, from low Earth orbit to the edge of the observable universe, with its real distance, and what is written about it was checked against the sources. What is invented is the ship, and how long it takes to get there, which is minutes to hours rather than the years or millennia it would really take. This site is Voyage's own, so read that with the grain of salt it deserves.
• Exoplanet. A catalogue app of every confirmed planet around another star, updated as they are found, with orbits drawn to scale. Not a game at all, and a good companion to any of the above. Free.

A note on the invented ones

Outer Wilds, No Man's Sky and Kerbal Space Program are not on this list because they are not on the iPhone, and because their universes are made up, however carefully. Kerbal's physics are real and its planets are not; Outer Wilds is a real solar system in miniature that never existed. They are among the best things ever made about space. They are just not about this space.