Halley is the most famous comet in history, recorded by astronomers at every return for more than two thousand years. Roughly every 76 years it dives from beyond Neptune to inside Venus’s orbit and lights up Earth’s skies. In 1986 ESA’s Giotto probe flew within about 600 km and returned the first close-up pictures of a comet nucleus: a dark, 15-km peanut venting bright jets of gas.
Chinese astronomers recorded it as far back as 240 BC.
Its 1066 apparition is stitched into the Bayeux Tapestry.
The nucleus reflects only ~4% of sunlight - darker than charcoal.
The comet that proved comets return
In 1705 Edmond Halley used Newton’s new theory of gravity to show that the bright comets of 1531, 1607 and 1682 followed the same orbit - they were one object, and he predicted it would return in 1758. When it appeared on schedule, years after his death, it was the first proof that comets are ordinary members of the Solar System obeying the same laws as planets, not omens drifting through the atmosphere.
Physical characteristics
Diameter
11 km
Dimensions
15 × 8 km
Mass
2.200e+14 kg
Geometric albedo
0.04
Atmosphere and composition
Atmosphere
None at rest; near the Sun it grows a glowing coma of gas and dust roughly 100,000 km across.
Composition
An “icy dirtball”: water ice, frozen CO and CO₂, and very dark carbon-rich dust.
Orbit and activity
Perihelion distance
0.59 AU
Aphelion distance
35.1 AU
Origin
Halley-type - likely scattered inward from the Kuiper belt long ago
Last perihelion
9 Feb 1986
Next perihelion
28 Jul 2061
Associated meteor shower
Orionids (October) and Eta Aquariids (May)
Discovery
Discovered by
Edmond Halley
Year
1705
How
recognised the comets of 1531, 1607 and 1682 as one object and predicted its 1758 return
Missions
GiottoESA · Flyby probe · 1985–1992 · completed
ESA’s first deep-space mission dived to within 596 km of Halley’s Comet in March 1986, returning the first close-up images of a comet nucleus - a dark, peanut-shaped body venting jets of gas and dust.