Comet Pons-Brooks underwent a second outburst in early October 2023, as soon as once more creating “horns,” as captured right here whereas it was in Draco. Credit score: Chris Schur
(Editor’s word: This text was first printed in October 2023.)
Comets have gotten a whole lot of press this 12 months, however not all of it good. Specifically, quite a few headlines have popped up a few “Satan Comet” that’s greater than Mount Everest on its means towards Earth — however what’s actually occurring? Let’s take a step again and dissect this satan and whether or not or not you ought to be fearful (spoiler: you shouldn’t!).
The so-called Satan Comet has a a lot much less terrifying identify: Comet 12P/Pons-Brooks. This short-period comet orbits the Solar as soon as each 71.2 years, much like the well-known Halley’s Comet. (For the document, any comet with a interval lower than about 200 years is taken into account quick-period.)
This comet isn’t a newcomer to the solar system scene. We’ve identified about Pons-Brooks ever since 1812, when comet hunter Jean-Louis Pons noticed it at 4th magnitude. However observations of the comet weren’t exact sufficient to foretell precisely when or the place it could return, so it was refound in 1883 by William Brooks. Extra trendy astronomers, working backward, assume possibly the comet was recorded on earlier passes, too, as early as 1385.
Why do we predict it’s greater than Everest? (Mount Everest, for the document, is 29,031.69 ft [8,848.86 meters], or 5.498 miles [8.849 kilometers] tall.) Effectively, figuring out the dimensions of a comet is troublesome with out immediately observing it by way of spacecraft or radar, however 2020 paper in Research Notes of the AAS estimated from its brightness on the time that its nucleus — the chunk of ice and rock that makes up the comet — is a few 10.5 miles (17 km) throughout. Yep, that’s greater than Everest, although they warn that is doubtless an overestimate as a result of the tactic they use makes it exhausting to inform precisely the place the nucleus stops and the coma of gasoline, ice, and dust coming off the comet’s floor begins.
Nonetheless, even overestimating its dimension does imply it’s nonetheless a whopping massive comet! However Halley, for the document, is nearly the identical dimension, some 9.3 miles (15 km) on its longest aspect — and we all know that one for positive, as a result of we’ve visited it with spacecraft.
The ‘Satan Comet’ horns, defined
Why is Pons-Brooks being known as the Satan Comet in any respect? Effectively, in late July, the comet underwent an outburst, blowing off a bunch of gasoline and dust and brightening by about 100 occasions, leaping in a single day from magnitude 17 to magnitude 12. Such outbursts are random, unpredictable, and not-entirely frequent, although researchers have famous that Pons-Brooks specifically has exhibited such habits earlier than, and several other occasions per orbit.
That outburst precipitated the coma to distort right into a horseshoe or horned form, with a darkish heart and shiny wings or factors. Therefore, many media shops nicknamed it the Satan Comet. (Some additionally known as it the Millennium Falcon comet, after the ship in Star Wars.) After the outburst, the comet settled down once more and its brightness remained regular till earlier this month, when it outburst once more, bringing the horns again.
Astronomers aren’t completely positive what’s inflicting the horns, however they assume it could possibly be because of the comet spewing gasoline and dust inconsistently. Perhaps there’s one space of the floor that isn’t blowing off steam, so to talk, so it stays darkish whereas the areas to both aspect of it are shiny. Or maybe it’s a shadow impact, the place denser materials and even topography on the heart of the comet seems to dam among the shiny materials behind it from our perspective. Regardless of the purpose, it’s scientifically attention-grabbing as a result of it’s intrinsic to the comet and its distinctive construction. Nevertheless it’s definitely not malicious!
The ‘Satan Comet’ is not any hazard to Earth
Along with making it sound like an evil horned beast, sensationalized headlines may give the impression that Pons-Brooks is an actual hazard to Earth. And positive, it’s heading our means… ish. However let me clarify why that’s actually not a priority.
When Pons-Brooks rounds the Solar at perihelion, it does so from a distance of 0.8 astronomical unit (74.4 million miles or 119.7 million km — 1 astronomical unit [AU] is the typical Earth-Solar distance, so Earth is 1 AU from the Solar). That’s fairly shut, and contained in the orbit of Earth, sure, however not at the same time as shut as Venus, which lies simply over 0.7 AU from the Solar.
As Pons-Brooks comes into after which flies out of the interior solar system, you would possibly assume it has to cross the orbit of Earth to get there. However you realize what? It doesn’t!
Do not forget that space is three-dimensional. And whereas all of the planets in our solar system orbit the Solar in a comparatively flat airplane, comets don’t must comply with that rule. Pons-Brooks has a extremely inclined orbit that’s primarily bringing it down from above the ecliptic (that airplane during which the planets orbit) because it rounds the Solar. So, Pons-Brooks will go between the orbits of Earth (on the skin) and Venus (on the within) earlier than heading out of the interior solar system once more. It won’t ever cross the orbit of Earth and may’t pose in the slightest degree of hazard by way of influence. The closet it will come to our planet on this orbit is about 1.5 AU in June 2024. That’s one and a half occasions the space of Earth from the Solar! So, completely nothing to fret about.
It is going to be seen throughout the total solar eclipse
The final time Comet Pons-Brooks handed perihelion, the closest level to the Solar in its orbit, was 1954. The following might be subsequent 12 months, on April 21, 2024. That’s simply two weeks after the April 8 total solar eclipse that may cross North America — and we now know that Comet Pons-Brooks will be in the sky near the Sun during totality. It’s prone to be shiny sufficient to select up with binoculars, and if it outbursts once more, maybe even seen to the bare eye within the daytime twilight introduced on because the Moon covers the Solar. This can be a particular deal with on prime of an already thrilling occasion, and one you received’t need to miss.
Comets should not solely stunning, however they provide us the chance to review the constructing blocks of our solar system and the interplay between the Solar and the objects that orbit it. So, the following time you hear in regards to the Satan Comet, you’ll know higher — it’s actually an thrilling and benign customer that may assist make an already once-in-a-lifetime eclipse much more memorable.
