In recent months, excitement has been growing over the approach of a new comet named Tsuchinshan-ATLAS, officially catalogued as C/2023 A3.
Comet Tsuchinchan-ATLAS (C/2023 A3) was first discovered at the Purple Mountain Observatory’s XuYi Station in China on January 9, 2023, then lost and discovered a second time 44 days later at the Asteroid Terrestrial Impact Last Alert System (ATLAS) research project station in Sutherland, South Africa. run high that it would turn into a bright object visible to the naked eye by the fall of 2024.
But a new technical document A study recently published on July 9 by a well-known comet expert indicates that rather than dazzling, comet Tsuchinshan-ATLAS will, in all likelihood, break up before it has a chance to orbit the sun in late September.
The report was written by Dr. Zdeněk Sekanina, a former NASA/JPL staffer and expert on split and dissolving comets. In his report, Dr. Sekanina provides three main reasons why he believes the comet is virtually finished:
“The purpose of this paper,” writes Dr. Sekanina, “is not to disappoint comet watchers who have been eagerly awaiting the discovery of a new naked-eye object next October, but to present scientific arguments that do not seem to support these hopes.” While openly admitting that predicting the disintegration of a comet before it reaches its closest point to the Sun (perihelion) is “a very risky undertaking,” Dr. Sekanina believes that “the time has come to take the plunge.”
Comet Tsuchinshan-ATLAS is expected to reach perihelion on September 27, at a distance of 58 million kilometers from the Sun, a distance equal to the average distance of Mercury, the closest planet to our star.
If you’re looking to see Comet Tsuchinshan-ATLAS this year (if it stays intact!), our guides to the best telescopes and best binoculars are a great place to start. And if you’re looking to take stellar photos of the night sky, check out our guides on how to photograph comets , or our guides on the best cameras for astrophotography and the best lenses for astrophotography .
Who do we believe?
Dr. Sekanina is highly respected in the field and his words carry a lot of weight in astronomical circles. Yet his thoughts about the future of the approaching comet have been met with conviction, mixed with skepticism and uncertainty.
One man who had high hopes for the Tsuchinshan-ATLAS spectacle but seems to have changed his mind after Dr. Sekanina’s findings is Joseph Marcus, a pathologist with a long-standing interest in comets. He is a resident of Washington University in St. Louis who founded and edited the quarterly Comet News Service published by the McDonnell Planetarium from 1975 to 1986. In an email to Space.com, Dr. Marcus wrote:
“The argument that Sekanina makes is compelling. In the unlikely event that C/2023 A3 survives to perihelion, its luminosity would increase by nearly 7 magnitudes” (a ratio of 600 times the luminosity). “But,” he adds, “that is now a moot point. I am betting on disintegration, as Sekanina now advocates, to whom I defer without reservation. In the end, the comet will soon be no more.”
But others are not convinced… yet.
Nick James, director of the British Astronomical Association’s comet section, said that while Sekanina’s study was “fascinating”, he found no evidence of non-gravitational acceleration. “It doesn’t look like a comet breaking up,” he said.
Dr. Clay Sherrod of Arkansas Sky Observatories in Petit Jean Mountain is another skeptic. “The comet isn’t going anywhere; it’s doing just fine and not breaking up in my opinion,” he notes.
Look “healthy”
Echoing Dr. Sherrod and Mr. James, Taras Prystavskian amateur astronomer living in Lviv, Ukraine, who enjoys photographing a variety of celestial objects such as comets. He provided Space.com with an image of Tsuchinshan-ATLAS taken on July 9, commenting, “To me, the comet looks healthy. Some images reveal that an ion tail has also appeared, but very faintly. I know that the appearance of an ion tail indicates that the nucleus of the comet is healthy. So there is a small hope of seeing a big show in the fall.”
Finally, Daniel Green of the Central Bureau of Electronic Telegrams (CBET) cautiously writes: “I think the comet looks healthy and is now showing an ion tail. I see no evidence of this comet disintegrating, so all we can do now is wait and see. We’ll know by the end of September (if not a little sooner) whether it will be a nice comet in October.”
Predicting the future is difficult!
Baseball sage Yogi Berra once said, “It’s hard to make predictions, especially about the future.” Those words are certainly true when it comes to predicting what a new comet might do.
While it is true that the brightness of Comet Tsuchinshan-ATLAS remained more or less stable from mid-April to late June at magnitude +10.5, there are signs that its brightness (based on the Comet Observation Database/COBS) slowly begins to recover during the first half of July.
Telescopes reveal that the comet’s dusty head has grown to a linear diameter of about 290,000 km, while its tail is now about 1.6 million km long. Unfortunately, for observers in the northern hemisphere, the comet is now too close to the sun’s glare to observe; in the coming weeks, only those living south of the equator will be able to observe its further progress.
Currently, the comet is about 254 million kilometres from the Sun and is experiencing temperatures of about -100°C. It is now beginning to cross the “water line” where frozen gases sublimate into vapour. If it manages to survive until perihelion on 27 September (which Dr Sekanina does not expect), it will be subjected to temperatures in excess of 1,600°C.
Hot Tea Analogy
Now imagine a piece of matter that probably dates back to the beginning of the solar system, nearly 5 billion years ago, that has been locked up all that time in an incredibly cold environment with temperatures close to absolute zero. Yet in the coming weeks, it will be faced with increasingly higher temperatures, by several hundred degrees.
So what happens when you pour hot tea into a cold glass?
This is what could happen to comet Tsuchinshan-ATLAS in the coming weeks; it could break up and completely collapse.
This is not an obvious conclusion.
Does this mean, as Dr. Sekanina titled his article, that it is a “Inevitable endgame” for the comet Tsuchinshan-ATLAS?
Not necessarily.
In November 2011, Australian amateur astronomer Terry Lovejoy discovered a very small comet, whose nucleus measured only 500 meters in diameter and would pass only 87,000 miles (140,000 km) from the surface of the sun. It was not expected to survive and yet it did and briefly provided a beautiful visual spectacle for observers in the southern hemisphere (shortly after, after circling the sun, Comet Lovejoy actually disintegrated as it headed into space).
In 1996, a comet that was billed as a spectacle was heading toward the Sun, then suddenly and inexplicably, it stopped shining from the first week of July until mid-October. Then, suddenly, the comet resumed its trajectory and began to shine, but just as quickly, its brightness dimmed again around mid-November. Some feared that the comet would become a failure. But in the spring of 1997, all fears were put to rest when the comet transformed into a magnificent celestial spectacle.
The name of the comet? Hale Bopp.
So maybe Yogi was right in making predictions about the future. East It is difficult. And perhaps the only thing we can do now, as Daniel Green suggests, is to adopt a “wait and see” attitude to see what Tsuchinshan-ATLAS will do in the days and weeks ahead. It may, as Dr. Sekanina predicts, disintegrate, but for now it is still whole and vigorous.
And to this end, let me invoke one last yogi-ism:
“It ain’t over till it’s over!”
Joe Rao is an instructor and guest speaker in New York Hayden PlanetariumHe writes about astronomy for Natural History ReviewTHE Farmers’ Almanac and other publications.