How can we see other galaxies from earth?
Galaxies are very large objects and they have large angular diameter. There is nothing that blocks light from galaxies to earth.
Andromeda galaxy which is the nearest spiral galaxy is 3.1 degree x 1 degree is angular size.
..Where as Sun is only 30 arc minute(half degree).
Andromeda is visible to naked eye.Other galaxies can be seen by using telescopes.