Comet Encke returns!

By Glenn Dawes 4 September 2023
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Comet Encke has the shortest orbital period of any known comet within our solar system.

It’s not as famous as Halley’s, but Comet 2P/Encke circles the Sun once every 3.3 years.

During its 2023 return it will be seen best at dawn in early September, above the north-eastern horizon.

After leaving the Auriga constellation, Encke heads towards the star Castor and will be closest to Earth on 12 September (one degree north) at about 10th magnitude.

By 22 September, Encke will be a few degrees above the horizon an hour before sunrise.

It will continue to drop into the dawn glow and disappear in early October.

How Comet 2P/Encke Got Its Name

Comets are usually named for their discoverer(s) or for the name of the observatory/telescope used in the discovery. However, this comet is not named after its discoverer(s). Instead it is named after Johann Franz Encke who calculated the comet’s orbit. The letter P indicates that 2P/Encke is a periodic comet. Periodic comets have an orbital period of less than 200 years.

Image: NASA’s MESSENGER spacecraft imaged comet 2P/Encke during its closest approach of the planet Mercury at 22:56 UTC on November 17. (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Southwest Research Institute)

Related: A stargazer’s guide to 2023