Update 0.990.46.1980: The Climate Model

Author: Dr. Megan Tannock

Have you ever wondered how the temperature might vary across different parts of the surface of your favorite planet or moon as the sun sets, or as you travel from the equator to the poles?

Wonder no more! We have introduced a climate model to SpaceEngine, which is currently available in the Public Beta here on Steam. Instructions for opting in and out of beta testing are available here. Please check the list of limitations at the bottom of this post before reporting any bugs.

You can find temperatures, pressures, and other information related to climate on a new tab on the in-game wiki for Climate. The tab displays a variety of parameters related to climate for planets and moons. The main feature of the tab is local temperatures that change with time, latitude, longitude, and altitude on planets and moons. For planets and moons with atmospheres, local pressure, density, and speed of sound values are available too. The Climate tab also shows daily and annual temperature averages, minimums, and maximums on planet and moon surfaces.

Information found on the Climate tab accounts for much more than just the position on a planet. The SpaceEngine climate model calculates a global temperature map based on energy transport calculations and accounts for planetary albedo, presence of an atmosphere, atmosphere properties (including wind speeds, radiation and advection, and greenhouse effects), internal planetary heating, day sides, night sides, axial tilt (for seasons and varying daylight hours, polar days and polar nights), eccentric orbits, tidal locking, and incident light of all stars in the system. Additionally, the altitude dependence had a major overhaul from its previous implementation. Now, we use real vertical temperature profile data for different types of atmospheres, allowing for exciting behavior like temperature inversions (like we see at the tropopause, stratopause, and mesopause for Earth).

Note this is not a visual update to planetary surfaces, but it’s a big step toward a more complete climate model in SpaceEngine.

Figure caption: The new Climate tab of the in-game wiki. Values update in real-time as you change the latitude, longitude, and altitude on a planet, and as time progresses. As with the other wiki tabs, you can change the units to your preferred units in the General tab in the Settings Menu.

How does the SpaceEngine climate model work?

A more detailed look at the physics and calculations behind our climate model will be available in the coming weeks!

All planets are born hot, but without a sustained energy source like fusion taking place inside of stars, they cool quickly. So unless planets are very young, almost all of their energy comes from stellar irradiation. Therefore, the main focus of SpaceEngine’s climate model is on stellar irradiation. We also account for internal planetary heating and greenhouse effects, when an atmosphere is present.

In our climate model, we start by calculating the Planetary Equilibrium Temperature (the theoretical temperature of a planet if it were a blackbody heated only by its parent star), then calculate surface temperature around the planet with a simple thermal transport model. This model has three variations for terrestrial planets, gas giant planets, and tidally locked planets (that can be terrestrial or gas giant). Each variation has a day/night temperature pattern based on real physics and observations of exoplanets. Every planet and moon in SpaceEngine has unique physical properties, so the final model for every planet is different and computed specifically for that planet. We have also introduced a global wind speed parameter (for planets with atmospheres)