What If Dark Comets Trigger Solar Flares
Another exotic Atlas hypothesis that makes easily testable predictions
There’s an old med school aphorism that goes:
When you hear hoofbeats, think horses, not zebras
It’s reasonable advice for a battlefield or an emergency room — where snap-diagnosis is crucial — but in other areas it can be a truly terrible heuristic. For people who happen to have a rare disease (which is estimated to sum up to about 10% of the population) the aphorism should make them angry. I’ve served as a patient advocate for friends with rare diseases, and I’ve hardly ever been angrier in my whole life than the time I watched a physician tell my zebra friend he was a horse until proven otherwise. It landed in my mind basically as, “I can’t figure you out, so why don’t you just go home with this horse tranquilizer and die already.”
I’m a research scientist, not a physician, and in grad school I was basically taught that when you hear hoofbeats, your experiments had better be able to tell the difference between horses and zebras. I’m increasingly feeling a little angry about the “think horses” orgy the astrophysics establishment has been tying itself into pretzels with on Atlas. These so-called “dark comets”1 are truly strange — and the strangeness just makes me think pretty much the exact opposite of horses. It makes me wonder whether Atlas is actually even weirder than the black-and-white zebra stripes revealed in some of the latest telescope images. Maybe the aphorism should be:
When you see zebras, think zoobreak
When I initially heard reports of exceptionally strong solar flares this week, I thought “nah — can’t be Atlas — it’s way over on the other side of the Sun.” Then my AI taught me that the Sun rotates on its axis every 26 days. If Atlas induced sunspots on the other side of the sun 13 days ago then the flares would be pointed at us now.
A scientific hypothesis is only as good as its experimentally testable predictions. Cheap predictions are especially high-value. So the first thing I did was check the record for Oumuamua, and bingo — there were exceptionally strong solar flares around the time of its closest approach to the sun (known as perihelion). A newer dark comet called Virgis2 will reach perihelion this coming Sunday. The flare hypothesis predicts intense solar storms late next week3.
A brilliant study by Beatriz Villarroel used archival photographic plates from the 1940s and ’50s to look for lights that appeared only transiently in the night sky. Villarroel found more than 10,000 transient lights occurring in an era long prior to the launch of the first satellite. She inferred that the objects must have been reflecting sunlight down from high in outer space because there was a dearth of transient lights in the Earth’s shadow. The amazing surprise is that the lights were statistically more common around the time of nuclear test detonations. The hypothesis that dark comet perihelions correlate with solar flares could be tested the same way — the prediction is that after exceptionally strong historical solar flares we might find a single tail-less transient object fleeing the inner solar system in old telescope images.
And guess what, horse-lovers! I’m still not necessarily invoking aliens! If Atlas is secretly much more massive than we think then I can easily imagine its gravity roiling the Sun. Or I can invoke the idea that dark comets have some kind of dark matter that emits some kind of dark energy that isn’t adequately explained by current physics. Picture me derisively waving my hands and saying “woo woo” while offering you a naturalistic explanation that doesn’t make any experimentally testable predictions.
Of course, I’m also not not invoking aliens. If the solar flare hypothesis were to prove true then aliens would strike me as a way less zebraistic explanation than invisible pink dark matter unicorns4.
Songs of the day: Beacon gets my nod for brainiest science-inflected band out there. Keep your eyes peeled for zebras in the Harm video.
I’ve been admiring Rebecca Bowen’s lively writing lately. In her comments section, I’ve been wrestling with comet terminology. The word comet derives from the ancient Greek word for “long hair” — referring to the streaming tails of familiar comets. Atlas doesn’t have long hair. Instead, it has a bizarre spike sticking straight up on top of its head. I propose the category names “longhair comet” (for the familiar class of solar system objects) or “Grimley comet” — in reference to Martin Short’s bizarre spike-haired sketch character.
The kludgy IAU technical name for Virgis is C/2025 V1 (Borisov). And no, it’s not the Borisov also known as I2/Borisov, it’s a different Borisov. Discovered by the same Borisov guy. Can we please get a coherent naming system up in here? Even if just among us lay folk?
The more I crawl through Kirby Proffitt’s math, the more I’m becoming a groupie for his Physical Time Medium model. It offers a plausible alien-free replacement for the beam of invisible pink dark energy in my cover art.