Nine years ago I sent a radio transmission with a unique attachment to the Alpha Centauri star system. That star cluster consists of 3 suns: Alpha Centauri, Beta Centauri and Proxima Centauri. From among trillions of stars, Proxima is closest to us. It is 4.2 light years from Earth. All stars have planets orbiting them, so Proxima must also have planets. Radio transmissions travel at the speed of light; therefore, my radio transmission would arrive...