If we assume Calvin is ~1 m tall, the text can’t be much more than 6 m × 10 m.
0.5° / arctan (10 meters / 30000 feet) gives is about 1/8th the diameter of the full moon. This number would be smaller if the pilot is not directly overhead, and larger if the jet is not at cruising altitude (i.e. taking off or landing).
If we assume Calvin is ~1 m tall, the text can’t be much more than 6 m × 10 m.
0.5° / arctan (10 meters / 30000 feet)gives is about 1/8th the diameter of the full moon. This number would be smaller if the pilot is not directly overhead, and larger if the jet is not at cruising altitude (i.e. taking off or landing).