This image made by the NASA/ESA Hubble Space Telescope shows NGC 6543, the Cat’s Eye Nebula. A planetary nebula forms when Sun-like stars gently eject their outer gaseous layers that form bright nebulae. In 1994, Hubble first revealed the nebula’s surprisingly intricate structures, including concentric gas shells, jets of high-speed gas, and unusual shock-induced knots of gas. The Hubble Space Telescope marks its 25th anniversary. A full decade in the making, Hubble rocketed into orbit on April 24, 1990, aboard space shuttle Discovery. (NASA, ESA, HEIC, Hubble Heritage Team (STScI/AURA) via AP)