Watch the Sun briefly drag the tail of Comet Satan

NASA's Stereo spacecraft detected a powerful explosion on the Sun, tearing off the tail of comet Pons Brooks, though it quickly regrew. This isn't the first time Stereo A has spotted the sun playing with a dirty snowball like this, but the images are particularly dramatic.

Comet tails are weak objects that occur when the solar wind pushes gas and dust created by sublimating ice away from the head of a comet. It doesn't take much to disable it; You sometimes see comets with two tails, one gaseous and one dusty, pointing in somewhat different directions, and the gaseous tail is particularly sensitive to conditions.

When solar flares lift coronal mass ejections (CMEs) from the Sun's surface, ejected particles can impact comet tails, and the STEREO spacecraft, which tracks solar storms, has often captured this. See, for example, this case in 2013 when two comets could be seen in the same field of view, one wagging its tail like a tadpole or a frozen but particularly defined sperm.

The STEREO spacecraft doesn't just watch comet tails for fun. Like their website Notes“Using comet tails as trackers could provide valuable data about solar wind conditions near the Sun.”

As its name suggests, the STEREO spacecraft is designed to provide two dual views of solar activity, one with an orbit a few weeks shorter than Earth, the other slightly longer. The typically long baseline gave NASA an unprecedented view of solar activity for a decade, but contact with STEREO B was lost in 2016, and even after it was recovered attempts to recover it failed.

STEREO A has continued, even if the abbreviation is now inaccurate. Its full name is the Solar-Terrestrial Relations Observatory A, and it has continued to help astronomers understand how the Sun's volatility affects Earth. As these images show, it does the same for other components of the solar system.

On April 12, STEREO A observed a large CME off the Sun. This event was in roughly the opposite direction to Earth, so it did not cause any aurora here, although another event occurred at about the same time The sky over Tasmania lit up. But after a week, Spaceweather.com took note Impact of the event on Comet Pons Brooks. In astronomical speak this was a “separation event” where the additional force in the solar wind caused the tail to separate from the comet's nucleus and sail off like Rohan's science on The two towers.

The effect was so strong partly because the coronal ejection was so powerful, but also because Pons Brookes was 120 million kilometers (75 million miles) from the Sun, 80% of Earth's distance. Although in stereo A the comet appears to be almost touching Jupiter, the giant planet was roughly 1 billion kilometers (620 million miles) away and would have barely been impacted.

Pons-Brooks hasn't really been living up to his title lately. It got the tag “Devil's Comet” because on its way it exploded several times (as it had on previous visits) and some of them produced what looked like devil horns. It is unfortunate that the explosions were stopped when they would have done their best to allow more people to see the comet. It's particularly unfortunate that none of them coincided with this coronal ejection. Imagine an eruption sweeping away something much brighter and more complex.

The good news is that although comets are often likened to cats, when it comes to their tails they are more like skinks, which can lose their appendages and grow them back.