Full Color Neptune Global Map from Hubble's OPAL Program (Dark Spot and Companion Clouds Closeup)
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.
Data were provided by the HST proposal 14492: M.H. Wong (PI), I. de Pater, J. Tollefson, and K. de Kleer (UC Berkeley), H. Hammel (Space Science Institute), S. Cook (AMNH), R. Hueso and A. Sanchez-Lavega (University of the Basque Country, Spain), A. Simon (NASA/GSFC), M. Delcroix (French Astronomical Society, SAF), L. Sromovsky and P. Fry (University of Wisconsin, Madison), G. Orton (JPL), and C. Baranec (University of Hawaii, Manoa).
F467M, F547M, and F763M
This image is a composite of separate exposures acquired by the WFC3/UVIS instrument. In the full globe and top detail image, several filters were used to sample various wavelengths. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: