Sources & attribution

Planet and Solar System data

Planet sizes, masses, densities, surface gravity, orbital periods and related values are based primarily on NASA data. The project’s original structured dataset was adapted from Devstronomy’s NASA data scraper and has since been extended and checked against current NASA and JPL reference tables.

• Devstronomy NASA data scraper — planets.json
• NASA Science — planetary data table and fact sheets
• NASA/JPL — planetary physical parameters
• NASA Science — planet sizes and locations

Live Earth–Moon distance

The live Earth–Moon distance is calculated for the current time with Astronomy Engine. That result is combined with NASA-based diameters for Earth, the Moon and the planets to test what fits in the gap. Astronomy Engine is open-source software released under the MIT License and validated by its maintainers against sources including JPL Horizons.

• Astronomy Engine
• NASA/JPL Horizons

The Sun’s energy and Earth’s share

The statement that Earth receives about one part in 2.2 billion of the Sun’s total energy is a rounded, derived comparison. NASA gives the Sun’s luminosity as about 3.85 × 10²⁶ watts and the power intercepted by Earth as about 1.8 × 10¹⁷ watts. Dividing the second figure by the first gives roughly one part in 2.1–2.2 billion.

The accompanying statement that about 30% of incoming solar energy is reflected to space is also rounded from NASA’s account of Earth’s energy budget.

• NASA Science glossary — solar luminosity
• NASA Cosmicopia — solar power intercepted by Earth
• NASA Earth Observatory — climate and Earth’s energy budget

Outer Solar System and scale

Explanations of the Kuiper Belt, heliosphere and Oort Cloud, and the approximate distances used in the large-scale journeys, are checked against NASA’s Solar System exploration material. The Oort Cloud is theoretical and its boundaries are estimates, so the experience presents those distances as approximate rather than exact edges.

• NASA Science — Kuiper Belt
• NASA Science — Oort Cloud facts
• NASA Science — the heliosphere

Maps

The football-scale maps are displayed with the open-source Leaflet mapping library. Map data and standard map tiles are provided by OpenStreetMap contributors. OpenStreetMap attribution also appears beside the maps themselves.

• Leaflet
• © OpenStreetMap contributors

Images and illustrations

NASA and NASA/JPL are the principal sources for photographic images of planets, moons and other Solar System objects. Some source images have been cropped, resized, had their backgrounds removed, or been combined into original explanatory graphics for this site. Other diagrams, scale models and interface illustrations were created for Scale the Solar System.

NASA should be acknowledged as the source of its material. NASA’s presence here does not imply that NASA has reviewed or endorsed this site. Individual NASA pages can also contain separately copyrighted third-party material, which is why image provenance continues to be checked at asset level.

• NASA Image and Video Library
• NASA images and media usage guidelines