ALT This animation starts with a small green dot flashing repeatedly in the center of the screen. The image zooms out slightly. The background has stars of various colors and sizes sprinkled against the darkness of space. Suddenly, the flashing green dot is replaced by a flashing purple dot. Next, the image changes to the source of the flashes, a multicolored disk of material with a bright white center. The disk spins clockwise with two beams of purple light coming out from the center on both ends. Just off to the side material from an orbiting yellow-orange star is pulled into the disk. As the star comes around to the foreground the disk disappears and its beams widen and turn light green. This image is watermarked “Artist’s concept” and “Credit: NASA's Goddard Space Flight Center.”