Milky Way and Andromeda Galaxy Collision Odds Slashed to 50-50 Within 10 Billion Years

Astronomers have revised the probability of a collision between the Milky Way and Andromeda galaxies to 50-50 within the next 10 billion years, less than previously thought. The collision, which could result in a new elliptical galaxy called Milkomeda, may not happen at all. However, the sun is expected to die in 5 billion years, and the earth will likely be engulfed by the sun, making the collision irrelevant for humanity.

Astronomers have revised the probability of a collision between the Milky Way and Andromeda galaxies to 50-50 within the next 10 billion years, less than previously thought. The collision, which could result in a new elliptical galaxy called Milkomeda, may not happen at all. However, the sun is expected to die in 5 billion years, and the Earth will likely be engulfed by the sun, making the collision irrelevant for humanity.

The Finnish-led team, led by Till Sawala of the University of Helsinki, reported their findings in a study published in Nature Astronomy [1]. They relied on the latest observations from NASA’s Hubble Space Telescope and the European Space Agency’s Gaia star-surveying spacecraft to simulate the possible scenarios facing the Milky Way and its neighboring Andromeda galaxy. The study found that the effects of the neighboring Triangulum galaxy increased the likelihood of a merger between the Milky Way and Andromeda, while the Large Magellanic Cloud decreased those chances.

The study also noted that the fate of the Milky Way galaxy remains highly uncertain, with many unknown factors contributing to the potential collision. However, the sun's future is "pretty much sealed," according to Sawala. "Of course, there is also a very significant chance that humanity will bring an end to itself still much before that, without any need for astrophysical help."

While the new study provides a more nuanced view of the Milky Way's future, it does not change the fact that the sun will eventually engulf Mercury, Venus, and possibly Earth. The sun is on course to run out of energy and die in another 5 billion years or so, becoming so big it will engulf these planets.

The revised probability of a collision between the Milky Way and Andromeda galaxies is a significant update from previous estimates, which had suggested a 50% chance of collision within the next 5 billion years. The new study, however, puts the chance of a collision at 50% within the next 10 billion years.

References:
[1] https://apnews.com/article/milky-way-andromeda-galaxies-collision-6bedc045554a5570ab9fc5ab67473268
[2] https://www.cnn.com/2025/06/02/science/milky-way-andromeda-galaxy-collision