Halley's Comet returns (2061)
After a journey of about 76 years, Halley's Comet returns to its closest point to the Sun on 28 July 2061. This time it passes the Sun on the same side as Earth, so it is expected to look much brighter than in 1986.
Available views: Orbit ✓ · Sky — (not visible in the sky)
The story
Halley's Comet is expected to pass its closest point to the Sun, called perihelion, on 28 July 2061. The very next day, 29 July, it comes closest to Earth, at a distance of about 0.48 AU, or roughly half the distance between Earth and the Sun.
This return is highly anticipated because of where the comet will be. In 1986, Halley was on the opposite side of the Sun from Earth as it swung around, making it the least favourable return on record, and at its brightest it reached only magnitude 2.1. In 2061 it will be on the same side of the Sun as Earth and is expected to reach about magnitude −0.3, similar to the brightest stars in the night sky.
Halley has been part of human records for a very long time. Its appearances go back to a Chinese record from 240 BC, and it also appears in the Bayeux Tapestry, which shows the Battle of Hastings in England in 1066. In 1910, Earth passed through the comet's tail on 19 May, and some people who feared the gas in the tail panicked.
On 9 December 2023, Halley passed its farthest point from the Sun, called aphelion. That distance is about 35 AU, roughly the distance of Pluto's orbit. The comet is now heading back towards the Sun, and the orbit view shows this return journey starting from beyond the orbit of Neptune.
When and where to see it
Halley is now more than 30 AU from the Sun and extremely faint. When it was last photographed in 2003, at a distance of 28 AU, it was magnitude 28.2, hundreds of millions of times fainter than the faintest stars visible to the naked eye. Choosing Halley in the orbit view draws its current position and its 76-year orbit, and moving the date to 28 July 2061 shows its passage through perihelion.
In the sky view, moving the date to late July 2061 and choosing Halley's return from the event list shows the comet's position and tail in the sky at that time (tail length and brightness are approximate). Setting the location to your own city shows when and in which direction the comet rises on a given day.
Dust shed by Halley comes back twice a year as meteor showers: the Eta Aquariids in early May and the Orionids in late October. While waiting for the comet, the radiants of these showers can be seen in the pre-dawn sky view around those dates.
See this for yourself — replay the moment in the orbit view
Past returns and history
Halley's orbital period changes a little at each return because the planets tug on it, and since 240 BC it has ranged between 74 and 80 years. During the 2061 return, it will pass fairly close to Jupiter on 9 September 2060 and come within about 0.054 AU of Venus on 20 August 2061.
In 1986, several spacecraft, including Giotto, visited Halley. Missions for 2061 have also been proposed, but none has been confirmed. ESA's Comet Interceptor, for comparison, is due to launch in 2028–2029 and wait at L2 for a newly discovered comet to visit; it is not aimed at Halley.
After 2061, the next return is in 2134. The comet will pass perihelion on 27 March that year and come within about 0.092 AU of Earth, roughly 14 million km, on 7 May. Its brightness is expected to reach about magnitude −2.0, even brighter than in 2061.
Why it matters
Halley's Comet was the first object to show that comets return on a regular schedule. In 1705 Edmond Halley argued that the comets seen in 1531, 1607 and 1682 were the same one, and predicted that it would return around 1758. When the comet was found again on 25 December 1758, people could see for themselves that Newton's theory of gravity worked.
On 14 March 1986, ESA's Giotto spacecraft flew within 596 km of Halley's nucleus and photographed it. The nucleus is about 15 by 8 km, with a shape compared to a peanut or a potato, and it is very dark. Because a comet loses ice and dust each time it comes near the Sun, scientists think Halley has been slowly shrinking over a very long time.
The 2061 return is also the fifth time Halley's prediction will come true, following the returns of 1759, 1835, 1910 and 1986. Since the 1986 return was hard to see, 2061 will give many people a chance to see how bright Halley can really be.
FAQ
How bright will it be?
About magnitude −0.3 is expected. That is much brighter than the 2.1 of 1986 and similar to the brightest stars.
Why will it be easier to see than in 1986?
In 2061 the comet will be on the same side of the Sun as Earth when it swings around. In 1986 it was on the opposite side.
Where is it now?
It passed aphelion at about 35 AU on 9 December 2023 and is now heading back towards the Sun. It is far too faint to see with the naked eye or an ordinary telescope.
When is the return after that?
In 2134. On 7 May it will come within about 0.092 AU of Earth and is expected to reach about magnitude −2.0.
Related
- Halley's Comet perihelion (1986)
- Comet Hale–Bopp perihelion
- Comet Tsuchinshan–ATLAS (2024)
- Halley's Comet — object index
- Neptune — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.