Venus, Mars and Earth, three out of the four inner or ‘rocky’ planets of the Solar System, have a lot in common – a solid surface you could walk on, a comparable surface composition, an atmosphere and a weather system.
Here is a patent for a portable planetarium.
Patent Information
Publication number: US3287832 A
Patent Title: Portable planetarium
Publication date: 29 Nov 1966
Filing date: 4 Sep 1962
Priority date: 4 Sep 1962
Inventors: Baerg Herbert R
Original Assignee: California Inst Res Found
Publication number: US3287832 A
Patent Title: Portable planetarium
Publication date: 29 Nov 1966
Filing date: 4 Sep 1962
Priority date: 4 Sep 1962
Inventors: Baerg Herbert R
Original Assignee: California Inst Res Found