July 1, 2011
An Egg in the Nest
images from LRO Featured Image (NASA/GSFC/Arizona State University)
Oblique shots are always the most dramatic, and these two just reconfirm that truism. Normally the Lunar Reconnaissance Orbiter views the surface directly under the spacecraft but for these images it was tilted 65° to better capture the oddity of a huge boulder (~120 m wide) sitting in a hollow at the summit of Tycho's central peak. The boulder had been spotted on an earlier vertical image and was targeted for a dramatic reobservation. The boulder sits on impact melt and it is possible that a smooth patch on top of the boulder is also melt rock. The interrelation between central peak rebound, impact melt ejection, and emplacement of a boulder should help constrain the sequence of events that all happened at about the same time. This giant boulder is visible on earlier views, especially from Kaguya, but no one appears to have commented on it. The brightness of this big boulder reminds me of an even larger piece of ejecta (if that is what it is) to the east of Tycho.
Rükl plate 64
Yesterday's LPOD: Good Job
Tomorrow's LPOD: Moons And Stars