Stargazing in October: Halloween fireballs

This month, we’ll enjoy a display of Orionid meteors, writes Nigel Henbest

The break-up of a giant comet may produce fireballs – and killer space rocks (Benjamin Inouye/CC BY 4.0)

When you’re out trick-or-treating this Halloween, keep an eye on the sky for an unusual cosmic treat – brilliant shooting stars called fireballs. They may represent the afterlife of a huge comet that died 20,000 years ago.

Every year, we experience regular showers of shooting stars, when the Earth ploughs into trails of dust shed by comets as they tramp around the solar system. This month, for instance, we’ll enjoy a display of Orionid meteors on the night of 21 October: these are fragments littering the orbit of Halley’s comet, that burn up in the Earth’s atmosphere way over our heads and seem to stream outwards from the constellation Orion.

From late October into mid-November, we cross the path of a comet called Encke – named after German astronomer Johann Encke who calculated its orbit in 1819. While a comet like Halley sweeps in from the far parts of the solar system, Encke’s comet doesn’t stray further out than the asteroid belt between Mars and Jupiter, looping around the sun in just 3.3 years. It’s a small and faint beast, though, so only rarely is Encke’s comet visible without a telescope.