The most famous comet of all — Halley’s comet — returns to our inner Solar System every ~76 years.

Using Newton’s gravitational law, Edmond Halley calculated that this 1682 comet also appeared in 1607 and 1531.

In 1705, he predicted the comet’s 1758 return and every subsequent ~76 years thereafter, periodically.

This prediction was confirmed by Johann Georg Pallich, who observed Halley’s comet on Christmas Day, 1758.

Every 74-79 years, the comet returns: most recently in 1986 and next in 2061.

Like all comets, fragments break off when it approaches the Sun.

Cometary debris spreads out along its orbit, creating meteors upon encountering our atmosphere.

Earth passes through this debris stream annually in mid-to-late October, creating the Orionids meteor shower.

Unlike most periodic comets, Halley’s comet crosses Earth’s orbit twice, also giving rise to May’s Eta Aquariids.

The link between meteor showers and comets is recent: uncovered by John Couch Adams in the 1860s.

To catch the Orionids, observe the southeast skies starting at midnight.

These meteors all originate from the constellation of Orion, appearing throughout the sky.

The peak yields ~30 meteors-per-hour, occurring from midnight to dawn on October 21-22.

Only December’s Geminids surpass the Orionids for the remainder of 2020.


Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.