Hal ‧ ley's com ‧ et /ˌhæliz ˈkɒmət, ˌheɪl- $ -ˌkɑː-/ BrE AmE
a ↑ comet (=an object in space like a bright ball with a long tail) that moves around the Sun and passes close to the Earth every 76 years. It was named after the English ↑ astronomer Edmund Halley (1656–1742), and it last appeared close to the Earth in 1986.