Yes, Io is tidally locked to Jupiter. This means that Io always shows the same face to Jupiter, just like the Moon always shows the same face to Earth.

Here's why:

* Tidal forces: Jupiter's immense gravity exerts a strong tidal force on Io. This force stretches Io along the line connecting the two bodies, creating a bulge on the side facing Jupiter and another on the opposite side.

* Rotation and orbital period: As Io orbits Jupiter, the tidal bulges are constantly shifting, creating friction within Io's interior. This friction slows down Io's rotation until its rotation period matches its orbital period.

* Result: This synchronization leads to Io being tidally locked, with one side always facing Jupiter.

This tidal locking is a common phenomenon in the solar system, particularly among moons orbiting large planets.