Eric Walker added a number of topics and Planetary Collisions Can Drop the Internal Pressures in Planets | www.caltech.edu and Radioactive elements may be crucial to the habitability of rocky planets to Planets, and added Planets to Outer space
Eric Walker added ESO Telescope Reveals What Could be the Smallest Dwarf Planet Yet in the Solar System | ESO to Dwarf planets, and added Dwarf planets to Planets