Is O3 Polar or Nonpolar??EMERGENCY!!?

So my A.P. Chem exam is tomorrow, and it just really freaked me out that my review books just claimed that O3 is polar. How is that possible? There can't be a difference in electronegativity between the same atom within a molecule, can there? I just figured it will have a strong-ish dipole moment due to a strong-ish London Dispersion Force because of the number of electrons but WHAT THE HELL. Sorry, I'm pretty stressed and this is really bugging me.