The Milky Way is doomed to collide with Andromeda in about 4.5 billion years
The core idea stands, but key numbers or details have changed.
TaughtOur galaxy and the Andromeda galaxy are falling toward each other and will smash together in roughly 4.5 billion years, merging into a single giant elliptical galaxy sometimes nicknamed 'Milkomeda.' It is a certainty, just a distant one.
NowA June 2025 study in Nature Astronomy ran 100,000 simulations with the latest Gaia and Hubble data and found only about a 50-50 chance the two galaxies collide within the next 10 billion years. The head-on merger is no longer a sure thing.
What actually happened
The certainty came from measuring Andromeda's approach and drawing a straight, doomed line. The new work adds a player the old calculations mostly ignored: the Large Magellanic Cloud, a sizable satellite galaxy whose gravity tugs the Milky Way just enough sideways to change the odds. Fold in the honest uncertainties in every galaxy's mass and motion, run the whole thing tens of thousands of times, and the outcomes split roughly evenly between a collision and a near-miss.
This is a genuine 'updated,' not a reversal; a merger is still very possible, and either way the Sun will have swelled into a red giant long before any of it plays out, so it changes nothing about Earth's fate. What changed is the word 'inevitable.' A collision presented for years as fixed astronomical destiny turns out to be closer to a coin flip.
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Who was taught this
Still standard through 2025, so anyone who finished school between 1950 and 2025 learned the earlier version.