Part 1- Driving down an open road, lost among the trees. The closer they come, the faster they seem to approach me-- the parallax: a change in the angle as it relates to the position from which I see. And from here we can measure the stars closer to us from those more distant, regardless of one shining more brightly. Caught in a curvature on a cosmic cruiser, we travel around the sun-- an ordinary star among billions, average in size, glowing yellow in our sky. A heart, fusing hydrogen to helium atoms, set on the edge of a spiral arm. We glimpse only a mere fraction with the naked eye-- just .0001% of those formed over time, gathered on a barred spiral we call the Milky Way. Herschel painstakingly categorized the stars he could see, counting pinpricks in the dark, estimating the size of our galaxy: 100 thousand light-years across, also rotating, slowly-- each revolution ...