Saturn Is Composed Mainly of Helium and This Gas
This page is the CodyCross answer for the clue below from Greece, Group 664, Puzzle 1 (World Heritage Sites).
Question is: Saturn Is Composed Mainly of Helium and This Gas
and the answer is: HYDROGEN
Word Meaning:
HYDROGEN — (uncountable) The lightest chemical element (symbol H), with an atomic number of 1 and atomic weight of 1.008.
Definitions from Wiktionary.