Compass and Scale Image of Neptune
The semi-major axis of Neptune's orbit about the Sun is 30.06 astronomical units (roughly 2.8 billion miles or 4.5 billion kilometers).
Neptune has a diameter of roughly 30,800 miles (49,600 kilometers) at the equator.
This image was created from HST data from proposal 12675: K. Noll, Z. Levay, M. Livio, C. Christian, H. Bond, L. Frattare, M. Mutchler, T. Borders, and W. Januszewski (Hubble Heritage Team/STScI).
F467N (46nm), F631N (63nm), and F845M (84nm)
This image is a composite of many separate exposures made by the WFC3/UVIS instrument on the Hubble Space Telescope using three different filters. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are:
Blue: F467N (46nm)
Green: F631N (63nm)
Red/orange: F845M (84nm)