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Comet Halley to reach farthest point from sun on December 9

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December 8, 2023

Comet Halley: Starfield, with a large bright comet with lavender and blue tails streaking out to the right. — Here’s Comet Halley when it visited the inner solar system in 1986. The comet will reach the farthest point from the sun on December 9, 2023. It’ll come closest to the sun again on July 28, 2061. Image via NASA.

Comet Halley farthest from the sun on Saturday

Comet Halley – the most famous of all comets – is coming to the end of the invisible tether binding it to our sun. This comet has been heading away from the sun since its last closest approach in 1986. Now it’s reaching the end of its outward journey, due to arrive at its farthest point from our sun on December 9, 2023. Afterwards, it’ll start making the trip back toward the sun, due to arrive in our vicinity by 2061.

Why is Comet Halley so famous? It was the first comet ever predicted to return. After observing a “hairy star” in 1682, English astronomer Edmond Halley looked at the historic record of such objects. He noted similarities in visits from objects in 1531, 1607 and 1682 and believed they were appearances of the same object. Then, he predicted that this “hairy star” would return in 1758.

And so it did, although Halley himself didn’t live to see it. But the comet now bears his name. Perhaps some of you have seen Comet Halley. The comet’s most recent close approach to the sun – called perihelion – was on February 9, 1986. Its next closest approach to the sun will be on July 28, 2061.

And that means means Comet Halley is now nearing its farthest from the sun – or aphelion – on December 9, 2023.

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Painting of a man with long wavy hair. He is wearing an academic robe and holding a book. — Portrait of Edmond Halley circa 1687 by Thomas Murray. Halley is famous for discovering that comets are objects that orbit the sun and can reappear in our skies. Comet Halley is named for him. Image via Wikimedia Commons (public domain).

Halley’s orbit

The relatively predictable and short orbit is what made Comet Halley famous. But – as with all things in nature – the orbit of Comet Halley isn’t precisely predictable. It varies slightly from 75 to 79 years. Still, it has a short-enough orbital period that it’s possible for someone to see it twice in their lifetime. Edmond Halley’s prediction of its return made this idea testable. It became a key to understanding what comets were.

Comet Halley is what we now call a short-period comet, or one that takes less than 200 years to orbit the sun. Long-period comets can take from 200 years up to millions of years to orbit the sun. In fact, it can take comets in the Oort Cloud as long as 30 million years to orbit the sun once.

Animation of a white dot on a narrow elliptical path that crosses the orbits of inner and outer planets. — This is the orbit of Comet Halley. It reaches perihelion, or closest point to the sun, every 75 to 79 years. It will reach aphelion, or farthest point from the sun, on December 9, 2023. Image via Wikimedia Commons (CC BY 4.0).

Comet Halley: Long streak with bright rounded end and straight fuzzy tail, on star field. — Here’s Comet Halley – probably the best-known comet – on May 29, 1910. Image via Wikimedia Commons (public domain).

The comet and 2 meteor showers

Clearly, aphelion – marking an object’s farthest point from the sun – isn’t a good time to observe Comet Halley. But if you don’t want to wait another 38 years to see at least bits of Comet Halley, I’ve got good news for you. We get to see parts of this comet every year in the form of meteors.

Comet Halley is the parent of two meteor showers. When comets orbit the sun, they leave bits of cometary dust behind. And for this comet, Earth’s orbit intersects two of these paths in one calendar year. The first is in May with the Eta Aquariid meteor shower. Then, in October, we intersect with another part of Halley’s path when we see the Orionid meteors.

A diagram showing how the comet orbit intersects twice a year with Earth orbit, at an angle. — This space diagram shows the path of Comet Halley during the most recent of its 76-years-apart visits, in late 1975 and early 1986. The stalks down or up to the ecliptic plane are at intervals of 1 month. The blue arrows are sightlines from Earth to the comet. Image via Guy Ottewell’s blog. Used with permission.

Bright white comet with wide glowing tail streaming out from it in starry deep blue sky. — Perhaps the most famous of all comets, Comet Halley is the parent object of both October’s Orionid meteor shower and May’s Eta Aquariid meteor shower. Comets are fragile, icy bodies. And this comet, like all comets, litters its orbit with icy debris. The bits of cometary debris enter our atmosphere to create a meteor shower. Image via NASA.

Bottom line: Comet Halley reaches its farthest point in its orbit from the sun – called aphelion – on December 9, 2023. Afterwards, it’ll begin its return trip to the inner solar system, reaching its closest point to the sun on July 28, 2061.

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December 8, 2023

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Kelly Kizer Whitt

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About the Author:

Kelly Kizer Whitt has been a science writer specializing in astronomy for more than two decades. She began her career at Astronomy Magazine, and she has made regular contributions to AstronomyToday and the Sierra Club, among other outlets. Her children’s picture book, Solar System Forecast, was published in 2012. She has also written a young adult dystopian novel titled A Different Sky. When she is not reading or writing about astronomy and staring up at the stars, she enjoys traveling to the national parks, creating crossword puzzles, running, tennis, and paddleboarding. Kelly lives in Wisconsin.