In science, 57 is the atomic number of lanthanum, the first element in the lanthanide series. Astronomically, it designates both Messier 57 - the famed Ring Nebula - and NGC 57, an elliptical galaxy.

In a 32-column table arranged by ascending atomic number, lanthanum (atomic number 57) follows barium (number 56) to start the f-block, with actinium below it.