Recent months have seen a gradual build-up of excitement about the approach of a new comet nicknamed Tsuchinshan-ATLAS, officially cataloged as C/2023 A3.
Comet Tsuchinchan-ATLAS (C/2023 A3) was first detected at the XuYi Station of the Purple Mountain Observatory in China on January 9, 2023, then lost and rediscovered 44 days later in the Last Warning System for asteroid impact (ATLAS) search project station in Sutherland, South Africa. The hopes were works high that it will become a bright object to the naked eye by the fall of 2024.
But new technical document published recently on July 9 by a well-known comet expert, states that instead of blinding, Comet Tsuchinshan-ATLAS will in all likelihood disintegrate and disintegrate before it has a chance to orbit the sun in late September.
The report comes from Dr. Zdenek Sekanina, a former NASA/JPL employee and expert on comet separation and dissolution. In his report, Dr. Sekanina gives three main reasons why he thinks the comet is almost complete:
“The purpose of this article,” wrote Dr. Sekanina, “is not to disappoint comet watchers who have been eagerly awaiting a new object with the naked eye next October, but to present scientific arguments that do not seem to substantiate such hopes.” Although he openly admits that predicting the breakup of a comet before it reaches its closest point to the sun (perihelion) is “undoubtedly a very risky endeavour”, Dr Sekinina believes that “the time has come to get on with it “.
Comet Tsuchinshan-ATLAS is expected to arrive at perihelion on September 27, at a distance of 36 million miles (58 million kilometers) from the sun – a distance equal to that of the average distance of Mercury, the closest planet to our star.
If you want to check out 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 want to take starry pictures of the night sky, check out our guides on how to photograph comets or those who recommend the best astrophotography cameras and the best astrophotography lenses.
Who do we trust?
Because Dr. Sekanina is well respected in the field, whatever he says carries a lot of weight in astronomical circles. Still, his thoughts on the future of the approaching comet are met with faith and conviction, mixed with skepticism and uncertainty.
One person who had high hopes for a great show from Tsuchinshan-ATLAS, but now seems to have changed his mind based on Dr. Sekanina’s conclusion, is Joseph Marcus, a pathologist with a long-time interest in comets. While in residence at Washington University in St. Louis, he 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 case that Sekanina brings is convincing. In the unlikely event that C/2023 A3 survives to perihelion, it will see a brightness increase of nearly 7 magnitudes’ (equal to a brightness increase factor of nearly 600 times). “But,” he adds, “that’s already a moot point. I am betting on disintegration, as Sekanina now defends and to whom I fully report. After all, the comet will soon be gone.”
But others aren’t convinced…yet.
Nick James, director of the British Astronomical Association’s Comet Section, said that while Sekanina’s report was “fascinating”, he found no evidence for non-gravitational accelerations. “It doesn’t look like a comet breaking up to me,” he says.
Another skeptic is Dr. Clay Sherrod of the Arkansas Celestial Observatories at Mount Petit Jean. “The comet isn’t going anywhere; she’s just fine and not ‘falling apart’ in my opinion,” he notes.
looking “healthy”
Echoing Dr. Sherrod and Mr. James, f Taras Prystavsky, an amateur astronomer living in Lviv, Ukraine, who enjoys photographing various celestial objects such as comets. He provided Space.com with a Tsuchinshan-ATLAS image taken on July 9, commenting that: “To me, the comet looks healthy. Some images reveal that an ion tail has appeared, but very weakly. I know the appearance of an ion tail indicates that the comet’s nucleus is healthy, so there is little hope of seeing a great show in the fall.”
Finally, there is Daniel Green of the Central Bureau of Electronic Telegrams (CBET), who cautiously writes: “I think the comet looks healthy and now also shows an ion tail. I see no evidence that this comet is disintegrating, so all we can do now is wait and see until the end of September (if not a little earlier) if it will be a clean comet in October.”
Predicting the future is hard!
The late great baseball sage Yogi Berra once said, “It’s hard to make predictions, especially about the future.” Those words certainly ring true for trying to predict what a new comet might do.
While it is true that the brightness of Comet Tsuchinshan-ATLAS is more or less flat from mid-April to late June at magnitude +10.5, there are indications that this brightness (based on Comet Observation Database/COBS) slowly starts to pick up again in the first half of July.
Telescopes reveal that the comet’s dusty head, or coma, has swelled to a linear diameter of approximately 180,000 miles (290,000 km), while its tail is now approximately 1 million miles (1.6 million km) long. Unfortunately, for viewers in the Northern Hemisphere, the comet is now approaching 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 future progress.
The comet is currently approximately 158 million miles (254 million km) from the sun and experiences temperatures of about -150°F (-100°C). It now begins to cross the “water line” where the frozen gases sublimate into steam. If it survives to perihelion on September 27 (something Dr. Sekanina does not expect to happen), it will be subjected to temperatures in excess of 1,000°F (1,600°C).
An analogy with hot tea
Now imagine this: Here we have a piece of matter that probably dates back to the beginning of the Solar System, nearly 5 billion years ago, that has been locked in an incredibly cold environment with temperatures close to absolute zero all that time. Yet it will face increasingly high temperatures of many hundreds of degrees over the coming weeks.
So what happens when you pour hot tea into a cold cup?
This may happen with Comet Tsuchinshan-ATLAS in the coming weeks; it may break and disintegrate completely.
It is not predetermined
Does this mean, as Dr. Sekanina titled his report, that it is “Inevitable End” about Comet Tsuchinshan-ATLAS?
Not necessarily.
In November 2011, Australian amateur astronomer Terry Lovejoy discovered a very small comet whose nucleus was only 1,600 feet (500 meters) in diameter and was about to pass only 87,000 miles (140,000 km) from the surface of the sun. He wasn’t expected to survive, but somehow he did and briefly put on a very nice visual show for Southern Hemisphere observers (a short time later, after orbiting the sun, Comet Lovejoy did disintegrate as it headed back into space).
And in 1996, a comet that was promoted as a “can’t-miss” spectacle headed toward the sun and then suddenly and inexplicably stopped shining all the way from the first week of July to mid-October. Then, suddenly, the comet got back on track and began to brighten, but then just as quickly, its brightness decreased again until mid-November. Some became very concerned that the Comet would turn out to be a failure. But in the spring of 1997, all fears were dispelled as the comet became a beautiful celestial exhibit.
The name of the comet? Hale-Bopp.
So maybe Yogi was right in making predictions about the future is hard. And perhaps the only thing we can do now, as Daniel Green suggests, is wait and see what Tsuchinshan-ATLAS does in the coming days and weeks. He may, as Dr. Sekanina predicts, fall apart, but right now he is still whole and hearty.
And to that end, let me refer to one last yogicism:
“It ain’t over till it’s over!”
Joe Rao serves as an instructor and guest speaker in New York Hayden Planetarium. He writes about astronomy Journal of Natural History.on Farmer’s Almanac and other publications.
