Space is an alien environment for humans. Our bodies are built for gravity; take it away and there are profound changes to our biology. Muscles and bones that keep us upright on Earth become weak.

Nearly a year in space put astronaut Scott Kelly's immune system on high alert and changed the activity of some of his genes compared to his Earth-bound identical twin, researchers said Friday.

The curious minds at What If land on Proxima Centauri b and explore its alien environment, revealing climate, terrain, and habitability.