The first space question the Canada Reads team asked me was, “What was it like to read in space?”

There is no sense of up or down in space.

Before I tell you more…Close your eyes and very lightly put the tips of your fingers on your eyelids. Then slowly move your head side to side. You will feel that your eyes do not smoothly track this motion. Instead, there is jerkiness in the motion of your eyes. This is a very high tech feature of our vestibular ocular reflex system that has evolved over millions of years under the influence of gravity. Gymnasts, skaters and dancers can perfect their somersaults, spins and jumps because of this capability that allows us to stop, spot or track motion.

In space, with the onset of weightlessness, this relationship between your eyes and your inner ear is no longer calibrated. If I move my head from side to side the shuttle walls do not stay still. In fact they will appear to oscillate and some astronauts may not even appreciate that their head has moved at all. If you move your head very quickly, the walls will appear to have the same jerkiness that you sensed with your fingers. This dynamically distorted visual field is very difficult to look at and for the first few hours in orbit I found it necessary to close my eyes after turning my head quickly.

The fact that this phenomenon is short lived shows an interesting thing about human adaptation. The vestibular ocular reflex system can recalibrate itself. Within just a few hours I could move my head slowly and the visual field would remain stable.

A few astronauts have complained that their visual acuity changes in weightlessness. This is supported by some predictions that once gravity is removed, the eyeball will change shape ever so slightly. Although we tried to do some simple experiments that measured these changes, my reading acuity appeared to stay the same. So for most, we can read in space just like we read on the ground…as long as we read normally.