With the exception of a few supernova remnants which are in our galaxy, most cosmic radio sources are “radio galaxies”. Although flare stars do emit radio waves occasionally, no ordinary stars with strong, steady radio emission have been found. The typical optical power of stars is from1030 ergs/sec(white dwarfs) to1038 ergs/sec(super giants). For comparison, the optical power of the sun is4×1033 ergs/sec.The typical radio power of supernova remnants is around1036 ergs/sec.For a giant galaxy (containing approximately1011−1012stars with a total mass of around1011⊙,where⊙ = solarmass = 2×1033 g), the optical power is around1044 ergs/sec.Radio emission from normal galaxies is generally weaker, the power ranging from1037−1039 ergs/sec.For certain peculiar galaxies, the so‐called “radio galaxies,” the radio emission rate ranges from1041−1044.5 ergs/sec.