Could Earth be hit by a rogue planet?

Yes — in principle, Earth could be hit by a rogue planet, but the chance is extraordinarily small and not something expected on any human timescale.

A rogue planet is a planet-mass object drifting through interstellar space rather than orbiting a star. Because space is vast and such objects are rare, a direct collision with Earth is considered vanishingly unlikely.

If a rogue planet ever came anywhere near the Solar System, the main risk would likely be its gravity: a close encounter could disturb the orbits of outer Solar System objects and, in a more extreme case, seriously alter Earth’s orbit. A sufficiently close pass could potentially move Earth out of the Sun’s habitable zone, but that would require an exceptionally near encounter and is itself very unlikely.

In practice, a rogue planet approaching the Solar System would probably not arrive unnoticed if it were large and close enough to matter; astronomers could potentially detect signs through direct infrared observations, gravitational effects on distant objects, or other indirect methods. Exact detection lead time would depend on the object’s size, temperature, path, and speed.

If a direct impact did occur, it would be a planet-scale catastrophe and would likely destroy Earth as a habitable world.

So the short answer is: yes, theoretically possible, but effectively not a practical concern.