Stellarscope

Stellarscopes are used to bottle the light of stars. Each star has a different color of light. It is illegal to bottle the light from the unmapped stars.

Book 1: Keeper
Sophie was assigned a star-mapping project in her Universe class by Sir Astin. She had to use a stellarscope to bottle the light of the 6 stars on the list and then bottle the light of a seventh, based on the pattern. She went with Dex to Moonglade, a beach with few visitors, to do their Universe homework. They set up a stellarscope to bottle the light of the stars. After Dex finished his assignment, Sophie bottled the light of the first 6 stars. Her pattern was metals, but when she plotted the stars on a map, the stars formed two lines pointing to Elementine, an unmapped star. The stellarscope got very hot after they bottled the light, because the light from Elementine was Quintessence, light in its truest form.

Book 3: Everblaze
Sophie and Fitz have to get lots of Quintessence to put out the Everblaze. They bottle the light of Elementine  using a stellarscope.