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Halley’s Comet – Comet · Returns every ~76 years
Image: NASA/W. Liller · Public domain
☄️ Comets · Comets & Space Visitors

Halley’s Comet

Comet · Returns every ~76 years

Halley’s Comet is the most famous comet of all, and the only bright comet that comes back often enough that a person can see it twice in a lifetime. Right now it is far out beyond Neptune, on its way back towards the Sun.

  • ~76 yearsOrbit
  • ~15 × 8 kmNucleus
  • 1986Last visit
🔭 Find it in the sky

Take a closer look

Darker than coal

Giotto’s pictures showed that Halley’s icy heart is wrapped in a crust darker than coal, reflecting only about 4% of the sunlight that hits it. Underneath lies ice mixed with dust. As the Sun warms the comet, jets of gas burst out through cracks and build its glowing head and tail.

A wrong-way orbit

Halley’s path around the Sun is a long, stretched-out oval. At its closest it swoops inside the orbit of Venus; at its farthest it drifts beyond Neptune, creeping along slowly. Strangest of all, it travels around the Sun in the opposite direction to all the planets.

Through the tail

In 1910 Earth passed through the edge of Halley’s tail. Some newspapers warned of poisonous gas, and a few sellers even made money from “comet pills”. Nothing happened at all – a comet’s tail is so thin that it is far emptier than the air around you.

How we found out

  1. 240 BC

    Chinese astronomers record it – one of the earliest known sightings.

  2. 1066

    It appears before the Battle of Hastings and is stitched into the Bayeux Tapestry.

  3. 1705

    Edmond Halley realises that comets seen in 1531, 1607 and 1682 were the same object, and predicts it will return in 1758.

  4. 1758

    On Christmas night it is spotted again, just as predicted. Halley had died 16 years earlier, but the comet gets his name.

  5. 1986

    The European spacecraft Giotto flies past and takes the first close-up pictures of a comet’s nucleus: a dark, peanut-shaped lump.

🤔 Something to wonder about

Where do comets come from?

See it yourself

It returns in 2061 – but you can see pieces of it every year! The Orionid meteor shower (around 21 October) and the Eta Aquariids (early May) are dust left behind by Halley’s Comet.

Got it?

Mark Halley’s Comet as explored to earn 10 XP.