Two Comets May Be Visible in Australian Skies During April

Australians may have the opportunity to observe two comets, C/2026 A1 MAPS and C/2025 R3 PanSTARRS, during April, pending their survival of close approaches to the Sun.

While both comets could potentially be visible, their simultaneous appearance would be an infrequent event, according to amateur astronomer Michael Mattiazzo.

Comet C/2026 A1 MAPS

Comet C/2026 A1 MAPS is projected to make its closest approach to the Sun during the first weekend of April.

The comet was identified on January 13 by four amateur astronomers using a remotely operated telescope in the Atacama Desert. It was discovered at a greater distance from the Sun than any previously identified sungrazer.

It is classified as a "Kreutz sungrazer," belonging to a family of comets believed to be fragments of a larger progenitor comet that underwent fragmentation after a close solar encounter in the 3rd or 4th century BCE. Historically, Kreutz sungrazers have produced some of the brightest comets observed. NASA's Solar and Heliospheric Observatory (SOHO) has detected thousands of smaller Kreutz fragments over time.

During its perihelion, the comet is expected to approach within 857,000 kilometers from the Sun's center, and 161,000 kilometers above its surface. Some sources also cite a distance of approximately 120,000 kilometers from the Sun's surface. This proximity is less than half the distance between Earth and the Moon.

Due to the intense heat and gravitational forces at such close proximity, experts estimate its survival chances at under 50 percent. Amateur astronomer Michael Mattiazzo noted that past comets, such as Comet Lovejoy in 2011, have survived similar close encounters.

Researchers utilized the James Webb Space Telescope's MIRI instrument to estimate the comet's diameter at approximately 400 meters. Recent observations have indicated a steady brightening, while astrophysicist Professor Jonti Horner observed a recent decrease in the comet's brightness, suggesting potential issues like disintegration or depletion of volatile materials.

If the comet remains intact after its solar pass, it could become visible to the naked eye from April 7 for approximately two weeks.

Astrophysicist Dr. Brad Tucker noted that the best viewing time would be shortly after sunset, low on the western horizon. If it holds together, its apparent magnitude could reach nearly -3, potentially making it brighter than most stars. It is expected to be more easily observable from the Southern Hemisphere. Visibility in broad daylight is also a possibility when it is closest to the Sun.

Real-time images of Comet A1 MAPS's passage can be monitored via NASA and ESA's Solar and Heliospheric Observatory (SOHO) spacecraft from approximately 5 AM AEDT on April 3 until 1 PM AEST on April 6. Continued clear visibility in SOHO imagery after its closest approach would indicate its survival.

Comet C/2025 R3 PanSTARRS

The second comet, C/2025 R3 PanSTARRS, is anticipated to become visible later in the month.

It was discovered in September by the Pan-STARRS system in Hawaii.

Its closest approach to the Sun will occur on April 19, at a distance of 74 million kilometers.

Due to its greater distance from the Sun compared to Comet A1 MAPS, it is considered more likely to survive its solar encounter.

This comet is expected to be visible from April 30 onwards. It is anticipated to be dimmer than Comet A1 MAPS, likely peaking at magnitude 5, which is generally visible to the naked eye, though binoculars are recommended for optimal viewing. It is expected to be well-positioned for Southern Hemisphere observers as it departs the inner solar system.

Comet R3 PanSTARRS last visited the Sun approximately 170,000 years ago. Professor Horner suggests that this current visit might be its last within the Solar System, as its speed could cause it to be ejected into interstellar space. However, its trajectory could still be altered by gas and dust ejection, potentially keeping it within the Solar System.

Viewing Information

For optimal viewing of either comet:

• Time and Direction: Observers are advised to look low on the western horizon shortly after sunset.
• Location: Viewing conditions improve in locations away from significant artificial light sources.
• Equipment: Binoculars are generally recommended to enhance visibility, especially for the dimmer Comet R3 PanSTARRS.
• Patience: Astronomers suggest that patience may be necessary, as comets can take a few days to become distinctly visible.