Double-A wrote:
On Monday, October 23, 2017 at 3:40:29 AM UTC-7, Sylvain wrote:
Le 23/10/2017 à 08:58, Sylvain a écrit :

http://blogs.discovermagazine.com/d-.../#.We2Ob2i0PIU


Probably a punctual collapse of a lava tube


the famous Rima Hadley is a collapse along of a lava tube


they found others, but this one is really bigger

The entrance is 50m from the cave 50km long


Could be habitable if the aliens aren't already there!

Double-A





Well how did you think the aliens living inside the moon fly their
spacecraft out.