Find the hidden message in the first three constellations based on the clues provided by the others.
The Constellations read:
SAVE EARTH MOTHER (Thanks @Wen)
Which logically rearranges to:
SAVE MOTHER EARTH
Each 'turning point' of a curve is assigned a letter. Specific locations within the square have letters assigned. I'm just having trouble working out where that center curve actually goes to, as the curves don't always quite reach the same turning point, it just seems to be general locale that is assigned to a letter.
Humankind has received a subliminal message to . . .
. . . S A V E E A R T H M O T H E R . . .
. . . and to illustrate TheGreatEscaper’s solution.
This puzzle is so neatly presented and solidly clued, it really doesn’t require more explanation.
So our crackerjack graphologists had time to authenticate the signature.
Gotta love the cosmic imagery and — conscientious as well — messagery.
The secret message states the truly difficult puzzle.