comet
n. countablen. a bright object in space that looks like a star with a long, glowing tail. It is made of ice and dust and moves around the sun.
n. a celestial body consisting of a nucleus of ice and dust that, when near the sun, creates a tail of gas and dust particles pointing away from the sun.
The comet is visible in the night sky this week.
Astronomers used high-powered telescopes to track the comet as it approached the inner solar system.
Unlike planets which follow nearly circular paths, a comet typically travels on a highly elliptical orbit, spending most of its existence in the freezing outer reaches of the solar system.
From Middle English comete, partly from Old English comēta and partly from Old French comete, both from Latin comētēs, from Ancient Greek κομήτης (komḗtēs, “longhaired”), short for ἀστὴρ κομήτης ([astēr] komētēs, "longhaired [star])" and referring to the tail of a comet, from κόμη (kómē, “hair”). Compare English faxed star and Latin crīnīta stēlla (“comet”, literally “(long) haired star”).