PPT Slide
Atmospheres are a natural consequence of planetary formation and evolution
Gases (e.g., H2O, CO2, Nitrogen, etc.) were present in the Solar nebula as it collapsed to form the Sun and planets…
If an object is massive enough, and through radioactive decay of elements, its interior will be heated, releasing gases that escape to the surface. Again, if the planet is massive enough, it can retain some gases….