In galaxy map there are unknown free planets, marked with a '?', and known free ones that list their diameter, and temperature.
It would be very useful to also mark their type (gas, dry sand, etc.). Since you are marking everything else (except free fields), why skip their type?
Appearance is not explained enough to new players, who have to colonize and abandon many planets, b4 getting used to appearance/type:(
Orange planets, for example, can be sand, dry, or gas.