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.
Let's go down by the River, take a walk with me, and you will see how pretty makin' love can be. Down by the River. Down by the River. Let's go down by the River, Baby take a walk with me. Let's go down by the River when the day is done and we lay on the levee 'neath the setting sun. The work day's over and the night just begun, and it's time for us to have a little good clean fun. Down by the River.