A newly discovered comet has astronomers excited, with the potential to be a spectacular sight in early April.
C/2026 A1 (MAPS) was spotted by a team of four amateur astronomers with a remotely operated telescope in the Atacama desert on January 13.
It quickly became apparent that the newly discovered object was a member of a group called the Kreutz sungrazing comets. These include many of the brightest and most spectacular comets ever seen.
Comet MAPS is moving on an extreme, highly elongated orbit around the Sun, and is diving toward a fiery date with our star. In early April, the comet will pass within just 120,000km of the Sun’s surface.
If the comet survives, it could become a spectacular sight in the evening sky in early April. It may even become visible in broad daylight as it swings closest to the Sun — unless it falls apart before then.
So what makes these sungrazers so exciting, and what can we expect?
Fragments of a mega-comet
Over the past 2,000 years, a series of spectacular comets have graced our skies. Without fanfare, they appear seemingly from nowhere, shining remarkably close to the Sun in the sky. Some even become bright enough to be visible in broad daylight.
Historically, the brightest comets often become known as “Great Comets.” The Great Comet of 1965 — C/1965 S1 (Ikeya-Seki) — was the brightest comet of the 20th century. Discovered just one month before its closest approach to the Sun, it got as bright as the full Moon, and was easily visible with the naked eye during the day.
The Great Comet of 1882, C/1882 R1, was even more impressive. At its brightest, it was a hundred times brighter than the full Moon, dazzling in the sky for several months.
We now know that all these bright comets from the last two millennia — the Kreutz sungrazing family — share a common origin. At some point in the past (potentially in the 3rd or 4th century B.C.), a giant cometary nucleus, more than 100km in diameter, came perilously close to the Sun’s surface. Some time after that close approach, far from the Sun, that comet split into two major fragments and shed lots of smaller pieces.
A few hundred years later, in the 3rd century A.D., those pieces returned as they journeyed on their long orbit around the Sun. Reports from 363 AD suggest there may even have been multiple comets visible with the naked eye in broad daylight at the same time. Those returning pieces again fragmented.
In the eleventh century, the two largest remaining pieces of the ancient mega-comet swung by again, becoming the Great Comets of 1106 and 1138. Once again, the pieces fragmented — and the products of those fragmentations have been seen as a series of comets through the past two centuries.
We’ve been due for a big one
Today, the Kreutz sungrazing family contains a vast number of smaller comets that fall apart en route toward the Sun, as well as larger pieces that can put on a fantastic show.
NASA’s Solar and Heliospheric Observatory, SOHO, has spotted thousands of Kreutz fragments over the years — tiny icebergs just meters or tens of meters across. Larger fragments swing by more rarely.
The most recent larger Kreutz sungrazer was visible in 2011. Discovered by Queensland astronomer Terry Lovejoy, the comet barely survived its close approach to the Sun, becoming as bright as the planet Venus in late December 2011.
According to the predictions of Czech-American astronomer Zdeněk Sekanina, we could potentially see two large, show-stopping sungrazers in the coming decades, with one potentially arriving in the next couple of years.
That comet would be a sibling to the Great Comets of 1965 and 1882, and a fragment of the Great Comet seen by Chinese observers in 1138.
Enter comet MAPS
Which all brings us to the newly discovered comet C/2026 A1 (MAPS). It’s moving on an orbit typical of Kreutz sungrazing comets, and already holds one record. At the time of its discovery, comet MAPS was farther from the Sun than any previous newly discovered sungrazer.
That suggests it might be a larger-than-usual fragment — perhaps.
The previous holder of this record was comet Ikeya-Seki in 1965, which proved to be the brightest of the 20th century. However, technology has moved on significantly in the past 70 years, and it seems very unlikely that the nucleus of comet MAPS is as large as that of Ikeya-Seki. In turn, that makes it unlikely that comet MAPS will be as bright.
Nevertheless, the fact that we’ve caught it so early means it’s either a reasonably large Kreutz fragment, or it’s currently in outburst — already falling apart. Fortunately, recent observations have shown it steadily brightening, which points to the former theory.
What can we expect from the new comet?
Overall, it’s too soon to tell. If — and that’s a big if — the comet survives its closest approach to the Sun (known as perihelion), it could put on a great show in early to mid-April.
If it holds together, it might get bright enough to be visible in broad daylight. Even if that doesn’t happen, the SOHO spacecraft will provide great images of the comet.
In the days following perihelion, the comet will move into the evening sky. Thanks to its orbit, like all Kreutz comets, it will be far easier to see from the southern hemisphere.
If the comet survives until perihelion, then fragments as it passes the Sun, it could brighten suddenly and unexpectedly. A late break-up might therefore be the best-case scenario for a dazzling show.
For now, we watch and wait.
Jonti Horner, Professor (Astrophysics), University of Southern Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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