Earth, Venus or Mars; Codycross Explores Ours
This page is the CodyCross answer for the clue below from Physics, Group 1886, Puzzle 1 (Thermal Conductivity).
Question is: Earth, Venus or Mars; Codycross Explores Ours
and the answer is: PLANET
Word Meaning:
PLANET — (now historical or astrology) Each of the seven major bodies which move relative to the fixed stars in the night sky—the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn.
Definitions from Wiktionary.