Every October, Earth runs through dust shed by comet 1P/Halley. The grains are small, old, and spread along the comet's orbit. When one hits the upper air, it makes an Orionid.
They arrive fast — about 66 km/s — which is why Orionids look quick and bright even though the particles are tiny. Speed, not size, does the work.
The same dust stream gives a second shower each year. Earth meets it again in May as the Eta Aquariids. One comet, two showers: the Orionids in October and the Eta Aquariids in spring.
Halley itself was last here in 1986 and is not due back until 2061. The meteors are the part of the comet we can still meet every year.
For peak timing and how to watch, use the Orionids 2026 guide. If you need the basic kit, see the Starter Kit.
Source: NASA's Orionids page.