spaceSpace and PhysicsspaceAstronomy

April Fools' Day Comet To Swing By Earth This Weekend


Jonathan O'Callaghan

Senior Staff Writer

Comet 41P/Tuttle-Giacombini-Kresák, pictured on March 25, 2017. Dominique Dierick/Flickr

A comet is going to fly relatively close to Earth on Saturday, April 1. Despite being April Fools’ day, this comet is very real – although it poses no threat to us.

It’s called Comet 41P/Tuttle-Giacobini-Kresák (T-G-K), and was discovered back in 1858 by astronomer Horace Tuttle. It was later rediscovered by Michel Giacobini in 1907 and Ľubor Kresák in 1951, hence the rather wordy name.


It belongs to a group of comets known as the “Jupiter comets”, which are comets that have been captured by the gravity of Jupiter and swing between the gas giant and the Sun. It takes about 5.4 years for this comet, which is about 1.4 kilometers (0.9 miles) across, to complete an orbit around the Sun.

On Saturday, it will pass closer to Earth than at any point since 1858. It will be 21.2 million kilometers (13.2 million miles) away on April Fools’ Day, about 55 times further than the Moon. It will appear in the far northern sky, between the constellations of Ursa Major and Draco the Dragon.

That might sound far, but it will be close enough for the comet to be studied by telescopes on Earth. And according to, there is a small chance it may experience a dramatic outburst in brightness if it repeats activity that has been seen in the past.

“In late May 1973, a few days before Comet T-G-K arrived at perihelion, the comet's brightness suddenly and inexplicably surged by 10 magnitudes; it became 10,000 times brighter over a span of just a day or two,” writes Joe Rao, adding that “outbursts in brightness tend to occur around the time T-G-K is passing closest to the Sun.” That is true of most comets.


In all likelihood, however, the comet will be fairly unexciting, and not visible to the naked eye. If it does go through a dramatic brightening event, though, it may just be visible.

But if you do want to catch a glimpse of it, Slooh will be showing a live stream of telescopes in the Canary Islands tracking the comet. The show will begin on Friday, March 31 at 8.30pm EDT (1.30am BST on April 1).


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