Neptune is the furthest planet from the Sun (according to definition of a "planet" as of the update time of this page) and consequently requires optical aid when viewed in any but the darkest skies. It appears blue because of the prevalence of methane in its atmosphere. Its largest moon, Triton, is visible using instruments at our disposal but because it is over 6 magnitudes dimmer than Neptune it is difficult to capture when its orbit brings it close to its planet.

 

Neptune field uncropped using a Canon 60Da on the Makemie 12-inch at prime focus (f/10). Stack of ten 1-minute photos.
Cropped from above photo showing close up of Neptune covering about 3 arc-minutes with North slightly right of up, East nearly to the left. This image shows Neptune's moon Triton just to the right of the planet. Neptune's glow has been masked and a photo of Neptune that is optimized for the planetary disk has been overlaid onto the field. The prominent star near center-bottom is 11th magnitude TYC5807-1418-1 and the faintest star is at magnitude 17.80.