What comet returns to the inner Solar System about every 76 years?

Halley’s Comet returns to the inner Solar System about every 76 years. Its official designation is 1P/Halley, and its orbital period varies because gravitational and physical effects slightly alter its path.

Astronomers had recorded earlier appearances, including one in 240 BC, but Edmond Halley recognized in 1705 that the comets seen in 1531, 1607, and 1682 were the same object. He predicted its return, and it reappeared in 1758, providing striking support for Newtonian gravitational theory.

Halley’s orbit is highly elongated and retrograde. It travels from near the Sun to beyond the orbit of Neptune, and its closest approach to the Sun lies between the orbits of Mercury and Venus. The comet last passed through the inner Solar System in 1986 and is expected to return in 2061.

It is often confused with other famous comets, such as Hale-Bopp or Hyakutake, but those do not follow Halley’s roughly 75-to-76-year cycle. Halley also gave its name to the Halley-type class of comets.