［The Daughter of Lycaon ライカンの娘］ Stephen Smith June 17, 2015Picture of the Day Comparing Ganymede and Callisto. The straight lines versus the swirls on Ganymede indicate that Ganymede has an intrinsic magnetic field, while Callisto …

［The Electronic Sun 電子的太陽］ Stephen Smith June 19, 2015Picture of the Day Spicules on the Sun in Hα (hydrogen-alpha) light at 6563 angstroms. 6563オングストロームのHα（水素アルファ）ライトでの太陽のスピキュール（棘）。 ―――――――― Jun 1…

［Moon Mountains 月の山］ Stephen Smith September 18, 2020Picture of the Day “Mount Doom” (bottom center) on Titan, with collapse feature Sotra Patera and flow feature Mohini Fluctus, the latter partially covered by dunes, from February 22…