Chronicle of a Disintegration Foretold (and Disproved)

Since its discovery in early 2023, comet Tsuchinshan–ATLAS promised to be one of the great comets of the 21st century. Many astronomy outlets published optimistic articles, predicting a comet potentially as brilliant as Hale-Bopp, which graced us with a spectacular display in 1997. 

Most comets that visit us aren’t bright enough to be seen without telescopes or binoculars. On average, it takes five to ten years to enjoy one that is easily visible to the naked eye. The most recent in this category was NEOWISE, which inspired us to step out of our homes during the height of the COVID-19 pandemic in 2020. 

Like many amateur astrophotographers, I began planning months ahead to observe the Tsuchinshan–ATLAS comet. From my location, I expected to see it leading the Sun at dawn towards the end of September 2024; later, from the end of the second week in October, I would see it rising gradually every day after sunset. I selected several observation spots with clear views to both the east and west. I only had to wait.

In early July, a paper by astronomer Zdenek Sekanina announced that the comet was doomed, and it would disintegrate before reaching perihelion (its closest approach to the Sun). For weeks, many outlets echoed Sekanina’s prediction, supporting the pessimism with recent observations indicating that the comet’s brightness wasn’t increasing.

Then, by late August, things started looking promising. The comet’s light curve suggested it would behave as initially predicted. This is typical: comets are known for being fickle, and they don’t seem to care what astronomers predict about their brightness. Once again, I had to wait.

My first sighting opportunity approached, but as usual, cloud cover thwarted my astrophotography plans. Just days before my long-awaited photo session with Mr comet—scheduled months in advance—Hurricane Helene covered much of the East Coast with clouds for nearly a week, as it wreaked havoc across several southern states, including the mountains region of North Carolina.

By the second week of October, the comet appeared in the evening sky, leaving Virgo to pass through the Serpent, dominated by Ophiuchus. This second opportunity to see the comet came with more and better days, and I made the most of it.

The comet reached perigee (its closest approach to Earth) on October 12. As night fell, it was clearly visible to the naked eye from Raleigh, though the sunset’s glow dimmed its brightness since it was still low on the horizon. The comet’s tail peeked shyly through the nosy clouds. It was beautiful to me, though perhaps not everyone would describe it as impressive. But the show was just beginning, and the story would be very different just one night later.

On October 13, I traveled to the Virginia border to escape light pollution. But there was a luminary that followed me everywhere and “polluted” the night sky: the Moon, just a few days away from being full. Even so, the comet’s brightness dominated the view westwards. In terms of magnitude, it was comparable to Betelgeuse, the ninth-brightest star. (John Coffey would’ve said: “like the name of the ghost, only not spelled the same”.) The most striking feature was its long tail, stretching about ten degrees. To put things in perspective, that’s equivalent to the width of twenty full moons side by side!

During these days, the comet gained nearly 4 degrees of altitude each night, making it easier to spot. On October 14, a cold front cleared the sky completely, producing nearly ideal conditions to take photos. On that date, the Moon’s increasing brightness allowed me to capture a portrait of the comet as if it were daytime: the landscape was clearly illuminated, and the sky appeared unnaturally blue for a night scene. But perhaps the most fascinating feature that was clearly visible that night was the anti-tail, seen as an extension of the nucleus pointing towards the Sun. This is a rare phenomenon, and it only occurs when Earth crosses the comet’s orbital plane. It was a truly beautiful and absolutely stunning sight!

The last day I photographed the comet was on October 21. I wanted a shot where it could be seen against a truly dark sky, so I had to wait until this date to avoid the blue hue in the sky caused by the moonlight. Although the comet had lost quite a bit of brightness by then, it was still a jewel in the sky when viewed from rural areas.

The comet disproved the prediction of its disintegration with a brightness that silenced every pessimistic voice, even outshining the glow of the full Moon. As it moved away from the Sun—perhaps never to return—its brilliance gradually faded. This splendid farewell also came with a touch of irony: the comet that wasn’t supposed to shine passed about 30 degrees from T Coronae Borealis—nicknamed “The Blaze Star”—a nova expected to explode by the end of September but never did. It seems that comets aren’t the only celestial bodies that enjoy mocking astronomers’ predictions.