NASA captures an exploding comet on its hunt for planets outside our solar system

Comet Wirtanen image captured using130P-DS Newtonian telescope Wikimedia


  • The National Aeronautics and Space Administration (NASA) captured a complete comet outburst for the first time using its Transiting Exoplanet Survey Satellite (TESS).
  • The comet, Wirtanen, burnt off nearly one million kilograms of material during the outburst.
  • Scientists are yet to determine what causes comets to explode periodically like that.
The National Aeronautics and Space Administration (NASA) was on the hunt for planets outside our solar system but, instead, it found itself a witness to an exploding comet — Wirtanen.

The agency’s Transiting Exoplanet Survey Satellite (TESS) captured the most complete and detailed observation of a naturally-occurring comet outburst to date. The explosion burnt off nearly one million kilograms of matter, according to the astronomers who made the discovery.

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Comet Wirtanen's outburst captured by TESSNASA

The resulting crater on the comet should be at least 20 meters across, according to a study published in The Astrophysical Journal Letters.

The comet in question, Wirtanen, is no stranger to Earth. Late last year, the comet flew by Earth at a speed of over 10 kilometers per second. Even though it was a little more than 11.5 million kilometers from the planet, it was the comet’s closest-ever approach.

Sequence of radar images of Wirtanen from 15 December 2019 showing apparent rotation of the nucleus in a counter-clockwise directionArecibo Observatory/NASA/NSF

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But this is the first time that Wirtanen’s trail dust has been detected.

Capturing the explosion

Comets normally have a trail of ice and dust behind them as sunlight vaporises their surface. But, from time to time, there’s a spontaneous outburst that temporarily increases the comet’s activity — which is what happened with Wirtanen.

According to the data from when Wirtanen visited Earth, a comet’s outburst is divided into two phases — an hour-long flash followed by a gradual increase in brightness for the next eight hours. Once Wirtanen reached its peak brightness, it gradually faded over the course of two weeks.
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NASA’s Hubble Space Telescope photographed comet Wirtanen on 13 December 2018, when the comet was 12 million kilometers from EarthNASA

Now, TESS has detailed and composite images from every 30 minutes over spanning over 20 days. The images can help scientists figure out what causes a comet to lose one million kilograms as it burns.

Until now, scientists don’t know what causes these outbursts aside from the fact that it has something to do with the conditions of the comet’s surface — like a heatwave that suddenly causes ice to explode.

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Wirtanen photographed in the southern hemisphere from Balcarce, ArgentinaEsteban J. Andrada, Wikemedia

Catching the tail

A comet’s trail and tail are two different things. The tail is the spray of gas and dust that runs behind the comet. The trail, on the other hand, is a field of large debris that outlines the comet’s orbital path. The main difference is that a tail changes direction depending on solar winds, but the trail stays in place.

“Tail dust is very fine, a lot like smoke. But trail dust is much larger—more like sand and pebbles. We think comets lose most of their mass through their dust trails. When the Earth runs into a comet’s dust trail, we get meteor showers,” said Michael Kelly, one of the co-authors of the paper.

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And, this is the first time that astronomers have been able to capture images of the trail.

See also:
A second mysterious object from interstellar space may be about to fly through our solar system

Origin story: All comets come from the same place next to the Sun

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