Comet C/2026 A1 (MAPS) approaches perihelion.

Comet C/2026 A1 (MAPS) will reach its perihelion (the closest point on its orbit to the Sun) on Saturday 4 April 2026, when it will be approximately 0.006 AU from the Sun (i.e. 0.6% of the distance from the Sun to the planet Earth, which is about 852 700 km, or a little over twice the distance between the Earth and the Moon). At this time the comet will be 1.05 AU from the Earth, in the constellation of Pisces, but it will not be visible due to its extreme closeness to the Sun.

The orbit and position of C/2026 A1 (MAPS) and the planets of the Inner Solar System on 4 April 2026.  JPL Small Body Database.

Should the comet survive this close encounter (which is not guaranteed), then it will reach apogee (the closest point on its orbit to the Earth) two days later, on 6 April 2026. At this point it will be 0.96 AU from us (i.e. 96% of the distance between the Earth and the Sun, or 143 614 000 km), still in the constellation of Pisces and still not visible. 

Comet C/2026 A1 (MAPS) was discovered on 13 January 2026 by the 0.28 m f/2.2 Schmidt telescope at the AMACS1 Observatory at San Pedro de Atacama. The name C/2026 A1 implies that it is a comet (C/) that it was discovered in the first two weeks of 2026 (period 2026 A), and that it was the first comet discovered in this period (1). The designation (MAPS) derives from the initials of the team which discovered it, Alain Maury, Georges Attard, Daniel Parrott, and Florian Signoret.

Discovery imagery for Comet C/2026 A1 (MAPS). Alain Maury/AMACS1 Observatory.

Comet C/2026 A1 (MAPS) is calculated to have an orbital period of 1900 years and a highly eccentric orbit tilted at an angle of 149° to the plain of the Solar System, or 59° to the plain of the Solar System but orbiting in a retrograde direction, the opposite direction to the planets and the majority of smaller bodies. This orbit brings it to 0.006 AU from the Sun at closest perihelion (0.6% of the distance between the Earth and the Sun) and out to 307 AU from the Sun at aphelion (307 times as far from the Sun as the Earth or about 10 times as far from the Sun as the planet Neptune, and considerably outside the Kuiper Belt). As a comet with a period of more than 200 years, C/2026 A1 (MAPS) is considered to be a non-Periodic Comet, since it is unlikely that it would be identified as the same body on another visit to the Inner Solar System. As a comet which comes within 0.01 AU of the Sun, C/2026 A1 (MAPS) is also considered to be a Kreutz Sungrazer Comet.

The Kreutz Sungrazer Comets, a group named after the nineteenth century German astronomer Heinrich Kreutz, have been shown to share a number of other properties, notably an orbital inclination which tends to be close to 144° relative to the plain of the Solar System, and an orbit which takes them to beyond 100 AU from the Sun. In 1967 the British astronomer Brian Marsden calculated that these comets could be subdivided into two groups, which clustered around the orbits of Comet Ikeya–Seki (which visited the Inner Solar System in 1965), and the 'Great Comet' of 1882. 

From this he calculated that these comets were all remnants of a single large comet, which had first broken into two halves during a close encounter with the Sun, then smaller pieces with each subsequent pass. He further calculated that the orbit of Ikeya–Seki appeared to be very similar to that of the 'Great Comet' of 1106, which was documented by observers across Europe, North Africa, and East Asia, and suggested that this might have been the parent body for the whole family. Subsequent researchers have suggested that there are more subgroups within this family, and that the Great Comet of 1106 was itself a fragment of an earlier body, which some of the other subgroups are derived separately from.

Calculations based upon the initial observations of C/2026 A1 (MAPS) led to the conclusion that the nucleus of this comet was about 2.4 km in diameter. However, subsequent observations by the James Webb Space Telescope have led to the conclusion that it is much smaller at about 400 m in diameter. This makes it one of the smallest known comets, as well as the first Kreutz Sungrazer to have had its nucleus directly measured, giving scientists a particular interest in whether it will survive its close encounter with the Sun.

An image of C/2026 A1 (MAPS) captured by the James Webb Space Telescope on 7 February 2026. Melina Thévenot/NASA/European Space Agency/Canadian Space Agency/James Webb Space Telescope/MIRI/Qicheng Zhang/Wikimedia Commons.

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The perihelion of Comet ISON (C/2012 S1).

Comet ISON (C/2012 S1) was discovered in September 2012 by Vitali Nevski and Artyom Novichonok of the International Scientific Optical Network observatory near Kislovodsk in the North Caucasus region of Russia. It is currently on a parabolic trajectory that will bring it to perihelion (the closest point of its trajectory to the Sun) within 2.7 Solar Radii of the Sun on 28 November 2013, before departing the inner Solar System again. It is not thought that this trajectory is, strictly speaking an orbit; it appears to have been disrupted from an orbit in the outermost part of the Oort Cloud, around seven million times as far from the Sun as the Earth, by an encounter with some object, and to be entering the inner Solar System for the first time, and it is by no means clear that it will survive its close encounter with the Sun, or that, if it does, it will remain in orbit about the Sun rather than being thrown completely out of the Solar System. Weather-or-not ISON (C/2012 S1) will survive perihelion is of great interest to astronomers, since objects from the outer Oort Cloud are seldom available for close observation, and if it does survive then its outward path should be easily observable from a number of Earth and space-based telescopes.

The calculated orbit of ISON (C/2012 S1). JPL Small Body Database Browser.

In a paper published on the arXiv online database at Cornell University Library on 9 September 2013 and submitted to the Astrophysical Journal Letters, Matthew Knight of the Lowell Observatory in Flagstaff, Arizona and the Applied Physics Laboratory at Johns Hopkins University and Kevin Walsh of the Southwest Research Institute attempt to calculate the likely fate of ISON (C/2012 S1) building a model based upon observations of the Kreutz Family of sungrazing comets.

The Kreutz Family of comets are thought to have a common origin, all following similar pathways, with orbital periods of 500-1000 years, thought to have diverged when a parent body broke up at some point in the remote past. All members of the family are thought to have made several passes through the inner Solar System, and as such they are likely to have rather different physical and chemical properties to ISON (C/2012 S1). Their paths also take them somewhat closer to the Sun than ISON (C/2012 S1). However they are the best available model for the possible fate of ISON (C/2012 S1).

Kreutz Family comets smaller than 200 m in diameter typically sublimate away (turn directly from a solid to a gas - liquids do not form in a vacuum) on their passage past the Sun. Comets larger than 200 m in diameter but less than 1 km do not simply sublimate away, but may break up into a number of smaller pieces as they pass the Sun, and these pieces commonly do sublimate away. Comets larger than 1 km usually survive perihelion, and even if they do break up, typically do so into pieces large enough to survive as viable comets in themselves.

Comet ISON (C/2012 S1) is though to be between 400 m and 2 km in diameter. This suggests that it will not simply sublimate away as it passes the Sun, but that there is a distinct chance that it may break up at perihelion. Knight and Walsh calculate that the comet will probably break up if its rotation is prograde (in the same direction as the body which it is orbiting, in this case the Sun) and its orbital period less than 9 hours, but that if it is rotation is retrograde (in the opposite direction to the Sun) or its rotation is prograde with an period of more than 9 hours then the comet will probably survive. They further estimate that there is a 30% chance that ISON (C/2012 S1) has a prograde rotation with a period of less than 9 hours.

See also The perihelion of Comet 103P/Hartley 2, The origin of Comet P/2006 VW₁₃₉, Comet C/2011 W3 (Lovejoy) survives a close encounter with the sun, The composition of Comet C/2009 P1 and The composition of Comet 10P/Tempel 2.

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Comet C/2011 W3 (Lovejoy) survives a close encounter with the sun.

Comet C/2011 W3 (Lovejoy) was discovered in November 2011 by Australian Terry Lovejoy, an amateur astronomer and astrophotographer. It was quickly discovered to belong to a group of comets known as Kreutz Sungrazers, which have extremely eccentric, long period-orbits that take them very close to the Sun. A typical Kreutz comet takes over a thousand years to orbit the Sun, is more that 100 AU at its aphelion (more than 100 times as far from the Sun as the Earth at the furthest point in its orbit, and passes within a few solar radii of the Sun at its perihelion (the closest point in its orbit to the Sun. Since orbiting objects speed up when they are close to the Sun and slow down when they are far away, this means that Kreutz comets only make rare and brief visits to the Inner Solar System. It is thought that the Kreutz Group comets are the result of the breakup of a single large object; since passing very close to the Sun the sun is unhealthy for a comet (an object made largely of ice), this breakup event is thought to have happened in the fairly recent past.

The orbit of C/2011 W3 (Lovejoy). Wikimedia Commons.

On 16 December 2011 C/2011 W3 (Lovejoy) reached its perihelion, coming within 1.2 solar radii, and disappearing behind the Sun as seen from the Earth. It was not thought that the comet would survive this encounter, but it re-emerged from the other side of the Sun, and continued on its journey back into the Outer Solar System.

This came as somewhat of a surprise to astronomers. Not only had C/2011 W3 (Lovejoy) been exposed to extreme heat from the Sun, but extreme tidal forces. In 1992 comet Shoemaker Levy 9 was torn apart by a close encounter with the planet Jupiter, but C/2011 W3 (Lovejoy) had survived a much closer encounter with the much larger Sun, and survived largely unscathed.

Comet C/2011 W3 (Lovejoy), bottom left, close to the Sun. Image taken by NASA's Hinode Satellite.

In a paper published in the online arXiv database at Cornell University Library on 8 March 2012, and submitted to the planetary science journal Icarus, a team of scientists from the Institut für Geophysik und extraterrestrische Physik at the Technische Universität Braunschweig, led by Bastian Gundlacha, propose an explanation for the survival of C/2011 W3 (Lovejoy).

Gundlacha et al. propose that C/2011 W3 was able to survive the tidal influence of the Sun because of the solar heat it was simultaneously subjected too. This caused material to erupt from all over the surface of the comet, effectively the equivalent of a rocket on every point on the surface of the comet, all pushing inwards towards the center. This pressure held C/2011 W3 together despite the tidal forces exerted upon it by the Sun, whereas Shoemaker Levy 9 was cold and inert at the time of its encounter with Jupiter, and was therefore torn apart by the much weaker tidal forces from the planet.

The forces exerted on comet C/2011 W3 at the time of its encounter with the sun. Although tidal forces were pulling the comet apart, this was more than compensated for by the pressure generated by material evaporating from the surface. From Gundlacha et al. (2012).

See also Two solar flares coming our way, The composition of Comet C/2009 P1, The composition of Comet 10P/Tempel 2, Water in the stratosphere of Jupiter and Solar storm baths Earth in protons.