Large radio telescopes, like the one in Arecibo, Puerto Rico, can detect extremely weak signals. Suppose one radio telescope is sensitive enough to detect a signal which lays down only 0.95 pW of power on an area of 6.1 × 1017 m2. (a) What would be the total power that would be received by the antenna, assuming that its diameter is 380 m? (b) What would be the power of a source at 17000 ly distance from Earth that could provide such a signal? A light-year is the distance light travels in one year.