In the first half of Friday's show, guest host Jimmy Church (email) welcomed theoretical archaeo-astronomer Walter Cruttenden, who discussed the recent scientific discoveries of a possible new planet as well as "gravity waves." In the second half, Jimmy welcomed Open Lines callers.
The Opportunity rover has discovered an unusual rock on the surface of Mars. Dubbed "Marquette Island," the boulder is different in composition than other known rocks from the Red Planet, and could reveal secrets about Mars' interior. More at Space.com.