spaceSpace and Physics

Chaotic Orbit Of Halley's Comet Explained


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockJul 1 2016, 15:25 UTC
Halley's Comet on March 8, 1986. NASA

In the wonderful world of astronomy, you can have perfectly regular events that happen in quite a chaotic way. And Halley’s Comet is one these happenings.

The most famous comet of all returns to our skies every 75 years, but its orbit is so strongly influenced by other bodies in the Solar System that, until now, astronomers couldn't predict its trajectory.


A team of Dutch and Scottish researchers has shown that the comet keeps the same orbit for about 300 years before slowly shifting, which contrasts with the traditional view that the comet has perturbations every 70 years.  

"We did the most accurate calculations of Halley and the planets ever," said researcher Tjarda Boekholt from Leiden University in a statement. "To our surprise, Halley's orbit was most strongly influenced by the planet Venus and not by Jupiter, the planet that was always pointed to as the biggest spoiler."

According to the study, accepted for publication in the Monthly Notices of the Royal Astronomical Society, Venus won’t always be the major player. In about 3,000 years, Halley’s comet will have a close encounter with Jupiter, which will give it a jolt and take back the role of the main perturber of the comet.

"After that, predictions of the orbit become less accurate, because the precise effect of Jupiter's gravity introduces a relatively large error in our calculations," added fellow researcher Inti Pelupessy.


Halley’s comet has been known of for thousands of years, named after Edmond Halley who first worked out that this comet regularly returned. The oldest surviving record of the comet is a Babylonian tablet from 164 BCE.

The comet was last in our neighborhood in 1986, when it was intercepted by the ESA spacecraft Giotto. This took the first close-up pictures of a comet, reaching 596 kilometers (370 miles) from Halley’s nucleus. No matter its shaky orbit, Halley’s Comet will grace us with its presence again in 2061.


Accurate integration of the orbits of 8 planets and the comet Halley for the next 10.000 years

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