A rare luminous red nova erupted in our neighboring galaxy, Andromeda, in October 2025.
The Andromeda Galaxy, or M31, is about 2.5 million light-years away and is the closest large galaxy to our own Milky Way. It’s home to billions of stars — and now, one of them just put on an incredible show.
So, What is a Luminous Red Nova? Well, Unlike a typical nova — which happens when material on the surface of a white dwarf star ignites — a luminous red nova is believed to be caused by two stars merging together. When they spiral into each other and finally collide, the result is a massive release of energy — and that produces a distinct red glow. This red glow is one of the key features that sets these novae apart from other cosmic explosions.
In October 2025, astronomers spotted a new bright red object in the halo of the Andromeda Galaxy. This transient event was given the designation AT2025abao — and it was no ordinary nova Starting around October 17, 2025, astronomers noted its unusual color and brightness compared to typical novae.
Luminous red novae are rare. They’re much less common than standard novae or supernovae, and they offer a unique glimpse into stellar evolution — especially the dramatic final stages when stars collide instead of exploding violently as they do in a supernova. And what makes AT2025abao even more fascinating is that we’re observing it in Andromeda our neighboring galaxy and the largest galaxy in our local group of galaxies. This gives astronomers a chance to study the event in another galaxy and compare it to similar events in our own Milky Way.
What happens is two stars orbiting each other gradually lose orbital energy. Eventually, they spiral inwards and merge. This merger expels material into space and heats it up, creating that signature red glow that lasts for weeks or even months. Unlike supernovae which is the death of a star (see my video explaining supernovae) luminous red novae may leave behind a single merged object! So, of course when I heard about this luminous red nova, I mean even the name sounds exotic, I had to see it. If you want to visually observe the current luminous red nova in the Andromeda Galaxy (AT2025abao) you’ll need at least a 6-inch or 150 mm telescope, but realistically bigger, it will be extremely faint; I think it is currently magnitude 14.5, so a larger aperture and dark skies will give you a much better chance of a visual seeing this rare event.
You might be able to get a photo of this luminous red nova in the Andromeda Galaxy and maybe even note how AT2025abao changes over time.
I was able to see it with my10” Reflector.
I have a very detailed star map showing how to locate it generously given to me by one of the viewers on the channel.
A rare luminous red nova erupted in the Andromeda Galaxy October 2025.
It’s designated AT2025abao and shows a distinct red color, likely from a stellar merger.
Events like this help astronomers study the stages of star evolution.
