planetographer

From planet +‎ -o- +‎ -grapher, perhaps modelled off of cartographer.

planetographer (plural planetographers)

1. (chiefly science fiction) Someone who studies planetography ("the branch of astronomy concerned with the description of the physical features of planets").
   • 2008, Charles Stross, Saturn's Children: A Space Opera, New York, N.Y.: Ace Books, →ISBN, page 269:

     In the century-plus since Eris was settled, we have already raised the temperature of its lithosphere by several degrees, just as we've thickened the atmosphere ot Callisto a thousandfold: if this goes on, the more annoyingly farsighted planetographers warn, we can look forward to an increased incidence ot icequakes and the threat of a year-round atmosphere.

• Jesse Sheidlower, editor (2001–2024), “planetographer, n.”, in Historical Dictionary of Science Fiction.