Looks can be deceiving, especially when it comes to celestial objects like galaxies and nebulas. These objects are so far away that astronomers cannot see their three-dimensional structure. The Helix Nebula, for example, resembles a doughnut in colorful images. Earlier images of this complex object — the gaseous envelope ejected by a dying, sun-like star — did not allow astronomers to precisely interpret its structure. One possible interpretation was that the Helix's form resembled a snake-like coil...