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Comet breaks are a timely topic at this time. The interstellar comet 2I / Borisov simply broke into at least two pieces. And although that comet is accelerating out of the Solar System, never to be seen again, most of them don’t leave the Solar System. Most of them orbit around the Sun and return to the inner Solar System over and over again.
A new document examines the potential danger to Earth from comets breaking into pieces. The author exposes that comet ruptures could have influenced the configuration of the ebb and flow of life on Earth. It could happen again.
In the deep history of the Solar System, there were many more comets than there are now. No one will ever know how many, but comets contain a lot of water ice, and scientists generally agree that one of the ways Earth got all its water is through a multitude of comet impacts over a vast period of weather.
A 2019 article looked at the modern threat comets pose to Earth. It is titled “The Danger of Comet Fragmentation”. The article is published in the Monthly Notices of the Royal Astronomical Society, and the sole author is W.M. Armagh Napier Observatory and Planetarium, Northern Ireland.
Napier gets down to work in the document’s introduction when he mentions the Younger Dryas (YDB) limit. The Younger Dryas was a cooling period that occurred about 12,900 to 11,700 years ago. Geological evidence shows a period of rapid cooling across the Earth’s northern hemisphere during that time.
The Younger Dryas is a remarkable moment in Earth’s history. It was one of several interruptions to global warming, and that warming started about 25,000 years ago. Researchers have long wondered if there was a heavenly cause for Younger Dryas’ cooling period, due to the large amount of platinum dust in Earth’s northern hemisphere since that time.
As Napier writes in the document, the heavenly cause “… is supported by the presence of high concentrations, at the limit, of platinum-rich dust at thirty sites throughout the northern hemisphere.” It also notes the presence of “impact proxies such as vitreous microsplints, nanodiamonds and an estimated 10 million tons of magnetic spherules that are said to be of impact origin.”
Napier also cites evidence of rapid changes in flora and fauna combined with platinum and other indications of celestial impacts, and rapid cooling of the climate. He also cites evidence of large-scale forest fires at the same time, when up to 10% of Earth’s biomass was burned over a period of weeks, perhaps just days.
In a sense, this is just the tip of the iceberg of evidence supporting an impact event as the cause of the Younger Dryas cooling. Napier cites many other studies in his article.
That background brings us to the central idea of his article: the proposition that comet breakdown poses a threat to Earth and has been responsible for climate turmoil in the past. Napier is not the first to investigate this. There are many research papers on the same topic, and Universe Today has covered several of them over the years.
Napier himself has written other documents on the subject. In 2010 he published the article “Paleolithic extinctions and the bullfighting complex” in the MNRAS. In that document he presented evidence that a large comet from 50 to 100 km broke, and part of it hit Earth. The impact (s), he argued, caused rapid cooling, and also Taurid meteor showers.
In that document he also wrote that “sub-kilometer bodies in meteorite currents may present the greatest danger of regional impact on time scales of human concern.”
That remains your concern, and your new document supports it. But this article tries to be more specific. He writes: “The objective of this article is to model the decay of the parent comet in more detail, to see if a plausible match can be made between the astronomical environment of that time and the terrestrial record; and therefore, more generally, to discuss the role of such comets in past climatic variations. ”
Much of this type of research looks at Comet Encke, also known as 2P / Encke. It is a periodic comet first recorded in 1786. Many researchers have wondered if Encke is responsible for terrestrial events like the Younger Dryas Cooling. There is even some evidence that the Tunguska Event was the result of a piece of Encke kite hitting Earth, and that the Encke we see now is only a fraction of the size of its former self.
This brings us to an essential part of this investigation. Comets separate, and we know that. Comets are not solid pieces of rock. They contain a large number of fractures and cracks, and in those holes are frozen volatiles. When a comet approaches the Sun, it warms up. Since some of those volatiles sublimate into gas, a comet can break down.
Depending on the size and trajectory of a comet when it breaks, the cross section of the spreading debris, or the length of the trail, could quickly become larger than Earth. This means that debris strikes are much more likely than kite core strikes. Encounters with these fragmentary swarms are a major driver of the paper.
Napier’s article focuses on the so-called Jupiter family comets, of which Comet Encke is a member. (Encke is actually a member of a subgroup called Encke-type comets, whose orbits do not reach Jupiter.) These comets are under Jupiter’s gravitational domain and have orbits of 20 years or less. Encke himself orbits the Sun every 3.3 years. Since these comets make frequent trips to the inner regions of the Solar System, they pose a greater risk to Earth.
Napier created models of the Jupiter family kites of 20 km, 50 km, 100 km and 150 km in diameter. (12, 31, 62 and 93 miles). The models followed the evolution of the comet for 10,000 years. The document notes that although comets lose mass by sublimation, that loss of mass is an order of magnitude less than the loss of mass by fragmentation during the 100th century simulation.
The study and its models point out that a comet is more likely to occur near perihelion, when the sun warms the comet.
The end result is as follows: most models “… predict something like 750-1500 division events producing groups of fragments each of mass> 1017 gm, on time scales of order 6000 – 20,000 years. At a meeting speed of? 30 km s? 1, 1017 gm of rubble carries 107 megatons of impact energy. “For comparison, the bomb the United States dropped on Hiroshima, Japan, was only 15 kilotons.
In any likely scenario, all the debris would not hit Earth. The debris trail would spread and become diffuse during the perihelion, but would decrease again during the aphelion.
The length of the debris trail lengthens over time, near the perihelion. But in the same way, the energy of the impact decreases as its speed decreases.
Simply put, Napier’s study shows how comets are likely to fragment and lose considerable mass during encounters with the inner Solar System. The debris trail can expand to a larger cross section than Earth, increasing the chances of impacts with Earth. In addition, the debris has considerable impact energy. But over time, that energy weakens and the trail of debris contracts again.
According to Napier’s article and other similar research, the fragmentation of comets is not rare and represents a real threat to humanity. There is considerable evidence that the disintegration of comets has already shaped Earth’s climate, as during the Younger Dryas inception. And it is possible that the fragmentation of the comet will lead to the disappearance of the Akkadian Empire.
In the conclusion of his article, the author writes: “I have modeled the decay of a large comet in a short period orbit, using Comet Encke as an archetype, and discovered that there is a reasonable expectation of one or more brief meteorites.” hurricanes, with intensities far beyond modern experience, in the course of parental disintegration. ”
The fact that a single comet can produce multiple meteor “hurricanes” is concerning. And not only the impacts of large bodies represent a threat. “Sufficient meteoric smoke can be created during such encounters to generate flash cores of a few years’ duration, along with widespread forest fires,” writes Napier.
The final sentence in his article reads: “The earth disturbances at the beginning of the Younger Dryas limit of 12,900 BP (before the present), and the simultaneous collapse of the first civilizations around 2350 BC, may have been triggered by events of this character. “
NASA and other agencies are actively cataloging potentially dangerous objects that can hit Earth, mostly asteroids. And the upcoming Double Asteroid Redirection Test Mission (DART) will test technologies to redirect a potentially dangerous asteroid.
But asteroids don’t tend to break like comets. Some research has been done on how to deal with dangerous kites, especially by deflecting them with lasers.
But when it comes to protecting Earth from the fragmentation of comets and their debris streams, there is much work to be done.
