Large radio telescopes, like the one in Arecibo, Puerto Rico, can detect extremely weak signals. Assume one radio telescope is sensitive enough to detect a signal which lays down only 1.2 pW of power on an area of 4.7 x 1013 m2. (a) What would be the total power that would be received with the antenna, assuming that its diameter is 340 m?(b) What would be the power of a source at 18000ly distance from Earth that could provide such a signal? Alight-year is the distance light travels in one year.