About this data
Planet Explorer covers the eight planets of our Solar System, plus a short selection of notable exoplanets found elsewhere in the Milky Way. Every planet card lists the same ten quick facts so worlds can be compared directly.
What the facts mean
- Distance from Sun is the mean orbital distance in astronomical units (1 AU = Earth's distance).
- Mass is expressed as a multiple of Earth's mass.
- Day length is the rotation period; year length is the orbital period.
- Average temperature is a surface value for rocky planets and a cloud-top value for the giants.
Figures follow widely published planetary reference values (NASA planetary fact sheets and equivalent sources), rounded for readability. Moon counts change as new discoveries are confirmed, so treat them as a recent snapshot rather than a final total.
The Milky Way is estimated to contain hundreds of billions of planets. Only a few thousand have been confirmed so far, which is why the exoplanet section is a curated highlight reel rather than a complete catalogue.