Halley's Comet: Facts, History and the Next Return

The orbit in numbers

Halley follows a long, stretched ellipse. At its closest point to the Sun, called perihelion, it was 0.5871 astronomical units (AU) away on February 9, 1986. One AU is the average Earth-Sun distance, about 150 million km (93 million miles), so that is about 87.8 million km (54.6 million miles). At its farthest point, called aphelion, NASA says it reached 35.25 AU in 1948, beyond the orbit of Neptune.

The period is not a fixed number. NASA says it has been as short as 74.42 years (1835 to 1910) and as long as 79.25 years (451 to 530). The planets cause the changes. When Edmond Halley's prediction came due in 1758, close passes by Jupiter and Saturn delayed the comet by a few months.

Halley's orbit is retrograde, which means it circles the Sun the opposite way from the planets. NASA also says the orbit is tilted 18 degrees to Earth's. The nucleus reflects only about 3 percent of the sunlight that hits it, which is why it looks so dark up close.

Sightings through history

NASA says astronomers have linked the comet's appearances to records going back more than 2,000 years.

• 240 BCE: The first firm record, in the Chinese chronicle known as Records of the Grand Historian.
• 837: Halley passed closest to Earth on April 10, at 0.033 AU (about 4.9 million km, or 3.1 million miles), and reached about magnitude -3.5 (on the magnitude scale, lower numbers are brighter).
• 1066: The comet appeared in April and came within about 14 million km (9 million miles) of Earth. English observers saw an omen, and Duke William of Normandy saw a good sign. It appears in the 11th-century Bayeux embroidery that tells the story of the Norman invasion, and the Battle of Hastings was fought on October 14.
• 1705: Edmond Halley used Isaac Newton's ideas about gravity to show that the bright comets of 1531, 1607 and 1682 were the same object.
• 1758: The predicted return arrived, a few months late because of Jupiter and Saturn.
• 1986: The latest return. Earth and the comet were on opposite sides of the Sun at perihelion, which made it a disappointing show for Earth-based observers.

The 1986 spacecraft encounters

An international group of spacecraft, sometimes called the Halley Armada, met the comet in 1986. NASA lists the Soviet Vega 1 and Vega 2 probes, ESA's Giotto, and Japan's Suisei and Sakigake, plus other spacecraft that collected data from farther away.

Giotto launched on July 2, 1985, and ESA gives March 14, 1986 as the encounter date. It returned the first close-up images of a comet nucleus and the first look at a nucleus's shape. ESA reports that the surface is very dark, and that jets of gas and dust erupt from it. It also found the first evidence of organic material in a comet. A separate ESA page lists the nucleus as about 16 by 8 by 8 km and says it is darker than coal.

The encounter was rough. Giotto recorded about 12,000 dust impacts during the flyby. After the particle that spun it, contact returned about 32 minutes later, and the probe kept sending data for about 24 hours. ESA says that by the time the spacecraft was reactivated in 1990, three instruments, including the camera, were disabled. It still flew by Comet Grigg-Skjellerup on July 10, 1992. The Rosetta mission later followed a comet for two years, and Halley's 1986 visit remains one of the early milestones.

The activity level was impressive. ESA says Halley released about 30 metric tons per second of gas and dust at its peak near the Sun. The general idea of what that means for a comet is in the overview of comet anatomy.

The meteor showers Halley makes

Every return leaves behind ice and rocky dust. NASA says this debris stream produces two weak meteor showers each year: the Eta Aquarids in May and the Orionids in October. A meteor is a flash of light made when a dust grain burns up in Earth's air. The guide to comet tails explains how a warming comet sheds that dust in the first place.

The 2026 Orionids are already over. NASA listed the peak night as October 21 to 22, with about 10 to 20 meteors per hour under dark skies, and activity running until about November 7. The Eta Aquarids peak in early May. NASA's next listed peak night is May 5 to 6, 2027, and it says the Southern Hemisphere is better placed for this shower because the radiant sits higher in the sky there. The full list of annual showers, with dates and tips, is in the guide to watching a meteor shower.

The return in 2061

NASA gives the next perihelion as July 28, 2061. It adds that Earth-based viewing should be favorable that time, since the comet and Earth will be on the same side of the Sun. That is the opposite of the 1986 geometry.

Brightness is harder to forecast than the date, and Halley's 1986 show is a reminder of how viewing geometry matters. The date can also shift by small amounts because planetary gravity keeps nudging the orbit. For how people watch comets today, see the guide to seeing a comet.

Common mistakes and myths

"Halley's Comet comes back every 76 years exactly." The average is 76 years, but the gaps have run from about 74.4 to 79.3 years.

"Edmond Halley discovered the comet." People had been recording it for over 2,000 years. Halley's contribution, in 1705, was to show that the comets of 1531, 1607 and 1682 were one object and to predict its return.

"Halley's Comet causes the Perseids." The Perseids come from Comet Swift-Tuttle, according to the Planetary Society. Halley's showers are the Eta Aquarids and the Orionids.

"You can see Halley's Comet now." As of November 2026 it is far from the Sun and will not return to the inner Solar System until 2061.

"A comet's return is the same show every time." The 1986 return was poor for observers on Earth, and 2061 is expected to be better.

Frequently asked questions

When will Halley's Comet return?

Its next perihelion is on July 28, 2061, according to NASA.

Is Halley's Comet or its meteor shower visible this year?

The comet itself is far from the Sun. Its dust makes the Orionids in October and the Eta Aquarids in May. The 2026 Orionids ended in early November, and NASA's next listed Eta Aquarid peak is May 5 to 6, 2027. Meteors are best watched with the naked eye. If you use binoculars for anything else in the sky, never point binoculars or a telescope at the Sun without a proper solar filter made for that purpose.

How big is Halley's nucleus?

NASA lists it as about 15 by 8 km (9.3 by 5 miles). ESA lists about 16 by 8 by 8 km.

Why does the orbital period change?

The gravity of the planets, mainly Jupiter and Saturn, speeds up or slows down the comet each time it passes. That is why the period ranges from 74.42 to 79.25 years.