The comets seen by the Romans during the day were part of a 2,400-year-long scene

It must have been an unforgettable sight, in November of the year 363. “Comets were visible at midday,” Roman historian Ammianus Marcellinus wrote. He himself saw them from Antioch, near the present-day Turkish-Syrian border. Seeing a comet with an amazing tail during the day is unique. And many others at the same time.

Comet expert Zdenek Sikanina, 85, at NASA’s Jet Propulsion Laboratory in California, thinks he knows what Marcellinus saw: the largest fragments from a decaying giant solid with an orbital period of about 735 years. Smaller remnants of that cosmic disintegration still fly around us today.

At the end of the 19th century, German astronomer Heinrich Kreutz was the first to suggest that the great comets of 1843, 1880 and 1882 were parts of the same icy celestial body. All three of them followed the same elongated orbit across the solar system, passing the Sun at a very small distance.

Astronomers are now familiar with several floating comets belonging to this Kreutz family, such as the Great Comet 1106, Comet Lovejoy (taken by Andre Kuipers in 2011 from the ISS) and the brilliant comet Ikeya-Seki from 1965, which can ancestors doing it. I still remember.

“The Guilty Mother”

The giant “mother comet” of all these tail stars appeared in 372 B.C. It was spotted and described by the Greek philosopher Aristotle. Nearly 2,400 years later, the European space probe SOHO still discovers new small comets from the Kreutz family almost every week.

Previous accounts seem to indicate that the largest debris of Aristotle’s Comet should have been visible in the sky around AD 356. But in a very comprehensive article recently published online, Sakina convincingly calculates that it might well be seven years later, at 363.

Therefore, the Marcellin diurnal comets were probably the first major parts of the parent comet. They themselves constituted the parent bodies of all subsequent comets of the Kreutz family, which have sparked fear, questioning, and scientific interest over the centuries.

‘so interesting’

Carl Battams of the US Naval Research Laboratory describes Sakina’s paper as “very interesting”. Batams is the scientific project leader for the Lasco Camera aboard Soho, which has so far discovered several thousand small comets of the Kreutz family.

“We still understand very little about the process of comet fragmentation, so any research in this area is of great value,” Battams said. “It teaches us a lot about comet evolution in general.”

The dazzling tail star of 1843 is believed to be the largest remaining portion of Aristotle’s Supercome. So I am happy to enjoy it again when the sun crosses again, towards the end of the 1970s. Please be patient.