Stars sometimes go ballistic, racing through interstellar space like bullets and tearing through clouds of gas. NASA’s Hubble Space Telescope has revealed 14 young, runaway stars plowing through regions of dense interstellar gas, creating brilliant arrowhead structures and trailing tails of glowing gas. These arrowheads, or bow shocks, form when the stars’ powerful stellar winds, streams of matter flowing from the stars, slam into surrounding dense gas. The phenomenon is similar to that seen when a speeding boat pushes through water on a lake.