The 18th element of the periodic table. a noble gas that makes up about 1% of Earth's atmosphere. Since it is the most abundant noble gas on Earth, it is used by humans for a variety of industrial and scientific processes that require a chemically and thermally inert gas. It is used in both incandescent lights and some gas-discharge lamps. Dr. Phlox once used an argon lamp to help the creature Sluggo survive away from his native argon-rich atmosphere. The shuttlecraft Galileo was stranded twice on terrestrial bodies with trace amounts of argon in their atmospheres, which isn't a lot, but it's weird that it happened twice.