Astronomy Picture of the Day . ... This cylindrical projection global map is one of six new color maps of Saturn's midsized icy moons, constructed using 10 years of image data from the Cassini spacecraft. ... SH2 155: The Cave Nebula . ... In the composite image, data taken through narrowband filters tracks the glow of ionized sulfur, hydrogen, and oxygen atoms in red, green, and blue hues. ... With those instructions, two nights went by with, well, clouds -- mostly. ... The Day After Mars . ...