Voyager communicates back to antennas on Earth with a 23-watt transmitter (or, more precisely, 22.4-watt on Voyager 1 and 23-watt on Voyager 2), which is about the equivalent of a refrigerator light bulb. By the time those signals get back to Earth, they are about one-tenth of a billion-billionth of a watt for Voyager 1 and two-tenths of a billion-billionth of a watt for Voyager 2.

Image credit: NASA/JPL-Caltech