The Science Behind Mercury's Transit of the Sun.

The May 9 transit of the sun by the planet Mercury was an astronomical wonder. The rare celestial event, which happens only 13 times a century, also provided an excellent scientific opportunity to study certain aspects of our solar system’s smallest planet. During a live, one-hour program on NASA TV, NASA science experts representing planetary, heliophysics and astrophysics discussed the science behind the Mercury transit as the phenomenon was occurring, and answered questions from the agency’s social media followers.