This past year, I've become a bit of a time traveler. But not in the quantum- mechanics-bending, continuum-shattering, wormhole-exploiting sense. No, this past year, I got serious about stargazing. After all, looking at the stars is like looking back in time. The heavens that rotate above us are largely the same as the skies our ancestors mythologized hundreds of years ago. While forests and plains disappear across the globe, replaced by man-made structures, the celestial world remains nearly unchanged. It...