CosmosComet1 min read

Halley's Comet

An icy visitor that returns every human lifetime.

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ESA / Giotto / Halley Multicolour Camera Team

Size: 11 km
Distance from Earth: 5.30 billion km
Temperature: 100 K (-173 °C)

Halley's Comet Mount Everest

Drawn to true scale.

Halley's CometSize11 km
Mount EverestSize8.8 km

Halley's Comet Sun Distance from Earth

Sun

Distance from Earth

150 million km

35.4×

farther from Earth

Halley's Comet

Distance from Earth

5.30 billion km

Halley's Comet is roughly 35.4× farther from Earth than Sun.

Picture this

Most people see Halley's Comet at most twice in their lives. It last visited in 1986. Its next pass is due in 2061. The same chunk of ice has been doing this since before the pyramids.

Fact

Halley's Comet is a peanut-shaped chunk of ice and dust about 15 km long, on a 76-year orbit that swings it from beyond Neptune to inside Venus's orbit. When it nears the Sun, the ice boils off and it grows two tails — one of dust, one of ionised gas — that stretch tens of millions of kilometres across the sky. Edmond Halley was the first to realise that comets seen in 1531, 1607, and 1682 were the same object returning. He predicted its 1758 comeback. He didn't live to see it, but it came.

Glossary

glossary.orbit.term

Did you know?

The 1986 ESA Giotto spacecraft flew within 600 km of Halley's nucleus — close enough that a dust grain punched through its camera. Most of what we know about the surface comes from that single fly-by.

Quick facts

Nucleus is roughly 15 × 8 km — irregular, peanut-shaped.
Orbital period: about 76 years. Last seen 1986; next expected ~2061.
Surface is darker than coal — one of the darkest objects in the Solar System.
Loses about a metre of surface ice each pass; will eventually fizzle out.
First record of an observation is from 240 BCE in Chinese chronicles — 22 confirmed apparitions on record.