Photo: NASA/W. Liller · Public domain
76 yrs
Halley's Comet returns about every 76 years, and its next visit is due in 2061.
5 min readLast updated
The short answer
Yes. Halley's Comet orbits the Sun about every 75 to 76 years. It last passed closest to the Sun in 1986, and its next return is expected in 2061.
Why it's true
Comets are icy bodies that travel on long, stretched orbits. Halley's swings in close to the Sun, where heat turns its ice into gas and releases dust, forming a glowing head and tail. Then it heads back out beyond the orbit of Neptune before turning around. One full loop takes roughly 76 years, varying a little because of pulls from the planets.
That period is close to a human lifetime, so Halley's is the only bright comet that most people have a realistic chance of seeing with their own eyes more than once. Records of it go back more than two thousand years, including Chinese observations and its famous appearance on the Bayeux Tapestry in 1066.
It was the first comet shown to return on a predictable schedule.
By the numbers
~76 yrs
Average orbital period
1758
Predicted return confirmed
1986
Most recent visit
2061
Next expected return
The backstory
In 1705, English astronomer Edmond Halley used Isaac Newton's new laws of gravity to study comet records. He noticed that comets seen in 1531, 1607 and 1682 followed very similar paths and concluded they were one object returning every 75 or 76 years. He predicted it would come back in 1758.
Halley died in 1742 and never saw his prediction tested. On Christmas night in 1758, a German amateur astronomer named Johann Palitzsch spotted the comet, and it reached its closest point to the Sun in early 1759. The successful forecast was a dramatic confirmation of Newton's physics, and the comet was named in Halley's honour.
A slowly shrinking comet
Each time Halley's passes the Sun, it loses some of its ice and dust. Over many thousands of years, this will gradually wear the comet down.
Scientists estimate it still has plenty of material for many more returns, so future generations will see it too.
Worth remembering
- Halley's Comet returns about every 76 years.
- Edmond Halley predicted its 1758 return using Newton's laws.
- Its next visit is due in 2061.
In context
Before Halley, many people thought comets were unpredictable omens, often linked with disasters or the deaths of kings. Showing that a comet could return on schedule turned it from a mystery into a member of the solar system, governed by the same laws as the planets.
Comets come in two broad groups. Short period comets like Halley's return within about two centuries, while long period comets can take thousands or even millions of years to complete one orbit.
Its 1986 visit was one of the least impressive in centuries, because Earth and the comet were on opposite sides of the Sun at the best moment. Many people saw only a faint smudge. The 2061 return is predicted to be much better placed for viewing. Anyone who was a child in 1986 has a chance of seeing it twice, which is part of what makes this comet such a personal, generational event.
A closer look
Inside a comet
Giotto revealed that Halley's nucleus is a dark, potato shaped body made of ice and dust, darker than coal. Jets of gas burst from its sunlit side.
Those images helped overturn the idea of comets as bright, clean snowballs. They are more like dirty iceballs.
Mark Twain and the comet
Writer Mark Twain was born in 1835, soon after the comet appeared, and said he expected to go out with it. He died in April 1910, a day after its closest approach to the Sun.
The story is often quoted because it captures how the comet's cycle matches a human lifetime.
1910 and the comet scare
In 1910 Earth passed through the comet's tail. Some people panicked after reports that the tail contained toxic gas, and sellers offered comet pills.
Astronomers explained the gas was far too thin to cause harm, and nothing happened.
Related facts
Halley's Comet appears on it the Bayeux Tapestry is really embroidery.
Another triumph of predicting the sky Neptune was found by mathematics.
Other icy worlds have jets too Enceladus sprays ice into space.
Newton's era changed how we see the world Harvard is older than calculus.
Key terms
- Nucleus
- The solid core of a comet, made of ice, dust and rock.
- Perihelion
- The point in an orbit where an object is closest to the Sun.
- Meteor shower
- A display of shooting stars as Earth passes through dust left by a comet.
Myth vs reality
Myth
Halley discovered the comet.
Reality
People had seen it for over two thousand years. Halley's achievement was proving it returns and predicting when.
People also ask
When will Halley's Comet return?
It is expected to reach its closest point to the Sun in mid 2061. Viewing conditions then should be better than in 1986.
How often does Halley's Comet come back?
About every 75 to 76 years on average. The exact period varies by a few years because planets tug on its orbit.
Who was Halley?
Edmond Halley was an English astronomer who predicted the comet's return using Newton's laws of motion and gravity. He died before seeing it come back.
Did spacecraft visit Halley's Comet?
Yes. In 1986 several probes flew past, including the European Space Agency's Giotto, which photographed its dark nucleus about 15 kilometers long.
Can we see bits of Halley's Comet every year?
Yes. Dust it has shed causes two annual meteor showers, the Eta Aquariids in May and the Orionids in October.
