This blackest month, when the stars emerging from early darkness recall the masterful illumination of a Rembrandt, we can inspect the canvas itself--the sky between the stars. Here is an emptiness rich in both mystery and misconception.
For starters, how much of the sky is occupied? If you’ve ever camped under desert skies spangled with seemingly endless stars, you’ll remember how the profusion appears to leave almost no space unfilled. But in truth, a straight line slashed across the firmament is unlikely to touch a single star. (Watch how rarely one is occulted by a passing satellite.) Just one (usually faint) star inhabits each patch about the size of 30 full moons. Space, not stars, dominates the heavens.
This vacancy is counterintuitive because we focus on objects rather than their environment. The moon, for example, is perceived as much larger than it really is; few would guess that it would ...
