Halley's Comet returns (2061)

After its 76-year loop Halley comes home — in a far better viewing geometry than 1986.

The moment of Halley's Comet returns (2061): https://nowsky.org/e/halley-return — opens at the right place and time, replayable, no login.

Available views: Orbit ✓ · Sky — (not visible in the sky)

The story

On 28 July 2061 Halley's Comet is due to return to perihelion after 76 years. Unlike 1986 it rounds the Sun on the same side as Earth, giving far better conditions for both brightness and tail — a peak near magnitude −0.3 is expected, bright enough to see from cities. Closest approach to Earth comes the day after perihelion, on 29 July.

Halley is the only comet whose every return has been recorded since 240 BC. It was in the sky at the Battle of Hastings in 1066, at the "comet panic" of 1910 and before the spacecraft armada of 1986. The 2061 return is roughly the thirty-first page of that record.

The reason 2061 is favourable is geometry: near perihelion the comet lies on the same side of the Sun as Earth, so instead of the "far-side return" of 1986 a bright comet will stand in the evening sky. Calculations put a long tail in the north-western evening sky of the northern summer.

A primary-school child of 2026 becomes an observer of 2061. For most of the world's population then it will be the first Halley of their lives, and for those who remember 1986 the second and last. Halley passed aphelion (35 AU) in December 2023 and is now on its way back; the orbit view replays the homeward journey from beyond Neptune's orbit.

Why it matters

Halley is the object that created the idea of a periodic comet. In 1705 Edmond Halley predicted that the comets of 1531, 1607 and 1682 were one body, and its return in 1758 was the first popular proof of Newtonian mechanics. The 2061 return is the fifth time that prediction comes true.

How the nucleus Giotto photographed from 596 km in 1986 — a dark peanut 15 by 8 km — has changed in 75 years is the scientific question. Several metres of surface sublimate at each perihelion, so a close encounter in 2061, if one is flown, would be the first comparison of a single comet's ageing at two epochs.

The viewing conditions of 2061 approach those of 1910, when Earth passed through Halley's tail and the comet spanned half the sky. 2061 will not be as dramatic, but for a generation that remembers the disappointment of 1986 it will show what kind of comet Halley really is.

How to watch

Halley, just past aphelion at about 35 AU, is a 28th-magnitude speck barely within reach of the largest telescopes. Select Halley in the orbit view for its current position and 76-year orbit, and move the time to 28 July 2061 for the geometry of perihelion.

Move the sky view to a late-July evening in 2061 and choose Halley's return in the event list to replay the comet and its tail in the north-west (tail length and brightness are approximate). With Seoul as the location it is calculated to stand above the north-western horizon in early evening.

Halley's dust returns twice a year as meteor showers — the Eta Aquariids in early May and the Orionids in late October; the sky view shows the radiant in the pre-dawn sky at those times.

See this for yourself — replay the moment in the orbit view

Background

The orbital elements for 2061 are computed from the 1986 observations and a model of non-gravitational forces (the recoil of outgassing), with perihelion uncertain by about a day. When large telescopes recover Halley in the late 2030s the prediction will be refined.

A close encounter in 2061, following the 1986 armada, is under discussion. Approaches such as Comet Interceptor (ESA, planned for 2029) waiting in space to intercept, or a rendezvous mission launched in the 2050s, have been proposed, but nothing is confirmed.

After 2061 the next return is 2134, when the comet is calculated to pass within 0.09 AU of Earth — a return more dramatic than 1910. Halley's period varies between 74 and 79 years from one return to the next because of planetary perturbations.

FAQ

How bright will it be?

A peak near magnitude −0.3 is expected — bright enough to see from cities.

Why better than 1986?

Near perihelion the comet lies on the same side of the Sun as Earth, so it is seen close by in the evening sky.

Where is it now?

Past aphelion (35 AU) in December 2023 and heading back, at 28th magnitude visible only to large telescopes.

When is the return after that?

2134, when it is calculated to pass within 0.09 AU of Earth — a more dramatic return.

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Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.