Pit craters are simply sink holes in the ground with near vertical walls and floors that are only visible when the sun is high in the sky.
from HiRISE: High Resolution Imaging Science Experiment http://ift.tt/1Vt9cHS
via IFTTT
Pit craters are simply sink holes in the ground with near vertical walls and floors that are only visible when the sun is high in the sky.
from HiRISE: High Resolution Imaging Science Experiment http://ift.tt/1Vt9cHS
via IFTTT
Telescopically 