The Blue Planetary (NGC 3918) is a planetary nebula in the constellation Centaurus, 2.5 degrees northwest of the star Delta Crux, that was discovered and named by John Herschel in 1834. In a 25-centimeter telescope, at low to medium power (75 to 120×), it appears as a small pale blue disk similar to that of Neptune. The image shown here was taken by the Hubble Space Telescope.