November will be active with bright and interesting comets. Now past its peak brightness, C/2025 A6 (Lemmon) begins the month in the evening sky at around 4th magnitude. It will fade to 5th magnitude by mid-month and, unfortunately, will also disappear from our view at that time as it moves close to the Sun. Another bright evening comet, C/2025 R2 (SWAN), starts the month at 7th magnitude but should quickly fade as the month progresses.

In the morning sky, we will see the return of the interstellar comet 3I/ATLAS, which reappears in early November for northern observers and late November for southern observers. It may shine as bright as magnitude 9 or 10 early in the month. Also visible in the morning sky is the “red comet” C/2025 K1 (ATLAS), which is also about magnitude 9 to 10.

The monthly ALPO Comet News PDF can be found here. All are encouraged to join the discussion over at Cloudy Nights at https://www.cloudynights.com/forums/topic/983706-alpo-comet-news-for-november-2025/

What a difference a few weeks make. Over the past few months, we have been complaining about the lack of bright comets in the sky. But that has all changed. October brings the chance to see a naked-eye object in comet C/2025 A6 (Lemmon), which may brighten to 3rd or 4th magnitude. It appears in the morning sky at the start of the month before moving into the evening sky around mid-month. Although not as bright, the recently discovered C/2025 R2 (SWAN) will be visible in the evening sky around 6th magnitude.

October also sees interstellar interloper 3I/ATLAS arrive at perihelion on October 29. Although it is too close to the Sun for most observers, hopefully we can enjoy images of the comet taken by spacecraft located throughout the inner solar system.

Also visible in October is short-period comet 210P/Christensen, which may reach 9th to 10th magnitude for southern hemisphere observers late in the month. Finally, C/2025 K1 (ATLAS), assuming it survives its close encounter with the Sun, should reappear in the morning sky at 9th to 10th magnitude for northern observers.

The monthly ALPO Comet News PDF can be found here. All are encouraged to join the discussion over at Cloudy Nights at https://www.cloudynights.com/topic/978264-alpo-comet-news-for-october-2025/

After a few slow months with no bright comets, activity is expected to increase in September. C/2025 A6 (Lemmon) has been an unexpected surprise, brightening much faster than anticipated. With an orbital period of approximately 1350 years, this comet has visited the inner solar system before. Although the rapid brightening might be due to a short-lived outburst, there are indications that the comet will be brighter in the long run. Currently visible only to observers in the Northern Hemisphere, Lemmon is a morning object at the start of the month with a magnitude of 10, possibly brightening to magnitude 7.2 by the end.

C/2025 K1 (ATLAS) is a dynamically new comet making its first pass through the inner solar system. That fact and its intrinsic faintness raise some questions about whether it will survive its close approach to the Sun. If it remains intact this month, it should brighten from about magnitude 11 to 9 or 10 before it gets too close to the Sun to be seen during the second half of August.

Interstellar comet 3I/ATLAS is also an evening object. Imagers should be able to detect it at magnitudes 15.5 to 14.1 before it gets too close to the Sun to be observable.

The monthly ALPO Comet News PDF can be found here. All are encouraged to join the discussion over at Cloudy Nights at https://www.cloudynights.com/topic/975151-alpo-comet-news-for-september-2025/ /

July brought news of the discovery of the third interstellar object and second interstellar comet, 3I/ATLAS. Although still three months from perihelion, 3I has been slow to brighten and is expected to be only a 15-16th magnitude object in August.

August continues our monthly streak without a bright comet. At least one comet will appear brighter than magnitude 12.0 in August as C/2025 K1 (ATLAS) brightens from magnitude 12 to 11 in the evening sky. We are still monitoring several inbound comets expected to be bright in the coming months, including C/2024 E1 (Wierzchos), which will be at 13th magnitude in the evening sky.

The monthly ALPO Comet News PDF can be found here. All are encouraged to join the discussion over at Cloudy Nights at https://www.cloudynights.com/topic/968931-alpo-comet-news-for-july-2025/

The bright comet drought of 2025 continues. Luckily, there is light at the end of the tunnel with several comets expected to become 10th magnitude or brighter over the next year, including 24P/Schaumasse, 88P/Howell, 210P/Christensen, C/2024 E1 (Wierzchos), C/2025 A6 (Lemmon), and C/2025 K1 (ATLAS). While some of these inbound comets are still very faint, and we’re talking 22nd faint, C/2025 K1 (ATLAS) will end the month at 12th to 13th magnitude. If you are like me and need your comets to be brighter than 10th magnitude to be observable, enjoy the break; brighter comets are on the way.

Fresh off the presses… A third interstellar object has been discovered. Designated 3I/2025 N1 (ATLAS), the comet is currently at 16-17th magnitude and may become as bright as 12-13th magnitude when it is at its best in September (for southern observers) and December (for northern observers).

The monthly ALPO Comet News PDF can be found here. All are encouraged to join the discussion over at Cloudy Nights at https://www.cloudynights.com/topic/968931-alpo-comet-news-for-july-2025/