The ornamental design for a planetariumprojector, as shown and described.
FIG. 1 is a perspective view of a planetarium projector;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is an enlarged perspective view of FIG. 1 thereof;
FIG. 9 is an enlarged front view of FIG. 2 thereof; and,
FIG. 10 is an enlarged top view thereof.
The broken lines shown in the figures are included for the purpose of illustrating portions of the planetarium projector and form no part of the claimed design.