The "Pi in the Sky" math challenge gives students a chance to take part in recent discoveries and upcoming celestial events, all while using math and pi just like NASA scientists and engineers. In this problem from the set , students use the mathematical constant pi to find out how much solar energy is lost on Earth when Mercury transits, or passes in front of, the Sun. Materials Pi in the Sky 3: Sun Screen worksheet – download PDF Pi in the Sky 3 answer key (third problem) – download PDF Backg