I posted this a few (hundred) pages back but it got buried before it was approved. I think now is a good time to post it again, given the circumstances.
This theory takes the stance that the message produced by the UP consists solely of a map, meant to guide us to a certain planet somewhere in/near the Pleiades. It relies on the assumption that the top two glyphs are binary numbers, with the least-significant bit on the right, and the bottom two glyphs simply define the "focus area" of the message, and can thus be safely ignored.
The top-left glyph represents the number 2, and combined with the quarter-circle around the center sphere, suggests that the planet we're looking for is land-able, and is the 2nd moon of its parent body.
The top-right glyph represents the number 3, and combined with the two quarter-circles surrounding the glyph, suggest that the parent body is the 3rd body in the system, and that it has two ring systems.
The bottom-left quadrant represents two lines, each coming from one of the system's stars (so the system must have at least two stars), and intersecting with the planet.
The bottom-right quadrant is a line coming from the north pole, to the target area.
To summarize: The top hemisphere helps us find out which body we're looking for, and the bottom hemisphere helps us find where on that body to look. I realize this theory makes a lot of assumptions, but I believe the majority of these assumptions are sound, especially when considering that the creators of the message would have wanted to make it as simple as possible to understand, similarly to the SETI message. The weakest assumption in my opinion is the one regarding the meaning of the bottom-left quadrant, but overall I think this theory is worth investigating.
Let me know what you all think.