How Jupiter rewrote comet 67P’s orbit

A 1959 close pass moved 67P’s perihelion from 2.7 AU to 1.28 AU — and another encounter is due in 2220.

Published 2026-10-23

Comet 67P has not always come this close to the Sun. Its present orbit is only a few decades old, and it is already scheduled for another change.^[2]

Where Jupiter-family comets come from

Comets with periods under about 20 years and orbits shaped mainly by Jupiter are called Jupiter-family comets.^[4] 67P is thought to have started out in the Kuiper belt, beyond Neptune, before successive encounters with the giant planets moved it inward.^[2]

February 4, 1959

That day the comet passed about 0.0515 AU (7.7 million km) from Jupiter. The encounter pulled its perihelion — its closest point to the Sun — from about 2.7 AU in to about 1.28 AU.^[2] Suddenly the comet’s ices were warming much more strongly at each return, which is part of why it was bright enough to be caught on a photographic plate ten years later.^[3]

The orbit today

• Perihelion ≈ 1.24 AU, a bit outside Earth’s orbit.^[1]
• Aphelion ≈ 5.68 AU, just beyond Jupiter.^[1]
• Period ≈ 2,350 days, about 6.4 years, with an inclination of about 7°.^[1]

The 2220 encounter

Orbit calculations show the comet passing about 0.14 AU from Jupiter in November 2220, moving perihelion in to about 0.8 AU — inside Earth’s orbit.^[2] Interactions like this continue until a comet is thrown out of the Solar System or hits the Sun or a planet.^[2]

Why it matters

A comet that moves closer to the Sun loses material faster. 67P already sheds about a metre of surface per orbit on average, so each orbital change also changes how quickly it wears away.^[2][5]

Numbered citations link to the sources list on the 67P/Churyumov–Gerasimenko overview page.