Tidal Lock

The moon is tidally locked to earth whereby it's "honeymooners" face always faces us, as seen in the graphic above, something scientists are now finding, with Kepler and earthbound telescopes, with tidally locked planets orbiting stars of all types, on almost a daily basis. With the "Eyeball" planets, as described by Sean Raymond in Nautilus, the interesting part is not the tidally locked condition but rather the zone residing between the light and dark side of the planet, where life can evolve just as life might be evolving in Enceladus and Europa, in subterranean oceans, due to the constant flexing of these moon's cores by the enormous gravitational pull of Saturn and Jupiter. 

Where on a hot eyeball planet could you live? It’s a classic Goldilocks story. The day side is roasting and dry. The night side is frigid and icy. In between, it’s just right! The sweet spot—let’s call it the “ring of life”—is at the terminator, the boundary between night and day. The ring of life is bounded by deserts on one side and ice on the other. There is a constant flow of water from the night side to the day side—a series of rivers, all flowing in the same direction. The Sun is fixed in the sky right at the horizon, and the area is in permanent light. Conditions are pretty much the same all the way across the ring of life. One can imagine vegetation following the rivers onto the day side until they dry up, with different ecosystems interspersed along the way. There could be mountains at the edge of the ice sheets, since the ice-covered continents would be heavily weighed down.

Life finds a way... Always - Robert E.