Suppose SETI researchers detect an extraterrestrial radio signal from a planet orbiting Proxima Centauri (the nearest star). Roughly how long ago was that signal sent, and how long would it take for any reply to get back to Proxima? image of a radio telescope Group of answer choices about 50 AU approximately 25,000 years about 4 years approximately 80,000 years over 100,000 years about 4 light-years