Halley's Comet
- a periodical comet with an orbital period of about 76 years, its reappearance in 1758-9 having been predicted by Edmond Halley. It was first recorded in 240 BC and last appeared, rather faintly, in 1985-6.哈雷彗星（公转周期为76年, 埃德蒙·哈雷准确预测了它会在1758-1759年重新出现; 关于此彗星的最早记载是在公元前240年, 最近一次较黯淡的出现是在1985-1986年）。