... Light Bridges on the Sun . ... Above, one of the sharpest photographs of the Sun ever taken shows two such light bridges that appeared late last month. ... Why is the sky near Antares and Rho Ophiuchi so colorful? ... Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. ... Early April brought some of the most intense auroral storms this decade. ... Three major sources contribute to the far-infrared sky: our Solar System, our Galaxy, and our Universe. ...