Refractometry

Abstract

The satellite, fully 150 kilometers in diameter, was close enough to Euterpe to shine like a brilliant dot of sparkling light. It was so close to the planet that one could see it sweep west to east across the sky, outstrip** the planet’s slow rotational motion. It brightened as it rose towards zenith, and dimmed as it dropped towards the horizon again. One watched it with fascination the first night; with less the second; and with a vague discontent the third – assuming the sky was clear on those nights, which it usually wasn’t.