The northern lights and southern lights are a dazzling spectacle for skywatchers lucky enough to see them, but fascinating science is behind what causes these impressive light shows.
Watch these six dots move across the map and be moved yourself: this is a story about coming of age, discovery, hardship, death and survival. Each dot is a tag attached to the talon of a Swainson's Hawk. We follow them on their very first migration, from northern California all the way down to Argentina.
Advertisement Four million miles (or if you prefer, 6.44 million kilometers) is quite a distance. It's the equivalent of driving around Earth's widest point, the equator, 160 times in a row. Well that's about as close to the sun as NASA is willing to take its new Parker Solar Probe (PSP).