A backlight includes at least one first light source, and a light guide arranged to receive light from the at least one first light source on a side surface thereof and to emit planar light from a principle surface thereof substantially perpendicular to the side surface. Each of the at least one first light source includes a first elongated light emitting member and a second elongated light emitting member arranged substantially parallel to the first light emitting member. The second light emitting member is different in length in the lengthwise direction from the first light emitting member.