One is the visible spectrum, as mentioned above, and the other is the radio spectrum. However, not all of the radio spectrum is useable for space communication. The available window spans from about 30 MHz to 30 GHz, although these are not absolute end frequencies.
Isaiah 43:2 (BBE) When you go through the waters, I will be with you; and through the rivers, they will not go over you: when you go through the fire, you will not be burned; and the flame will have no power over you.saiah 43:2 (CJB) When you pass through water, I will be with you; when you pass through rivers, they will not overwhelm you; when you walk through fire, you will not be scorched-the flame will not burn you.
There is a river called the river of no return, sometimes it's peaceful and sometimes wild and free. Love is a traveller on the river of no return, swept on forever to be lost in the stormy sea.(Wailaree). I can hear the river call (no return, no return). I can hear my lover call,come to me. I lost my love on the river, and forever my heart will yearn. Gone, gone forever, down the river of no return.