... The far side of the Moon is rough and filled with craters. By comparison, the near side of the Moon, the side we always see, is relatively smooth. Since the Moon is rotation locked to always point the same side toward Earth, humanity has only glimpsed the lunar farside recently -- last century. Iridescent clouds . ... Why would clouds appear to be different colors? ... These clouds are formed of small water droplets of nearly uniform size. ... Will the Universe End in a Big Rip . ...