Neptune in Natural Colors
The semi-major axis of Neptune's orbit about the Sun is 30.06 Astronomical Units (A.U.) or roughly 4.5 billion km.
Neptune has a diameter of roughly 30,800 miles (49,600 km) at the equator.
The Neptune STIS/CCD data are from the HST proposal 9330: E. Karkoschka (U. AZ), M. Lemmon (Texas A&M), M. Tomasko (U. AZ)
Note: Neptune images within this press release were taken with STIS/CCD.
G430L, G750L, CLEAR, and F28X50LP
NASA and Erich Karkoschka, University of Arizona