Anyway, let's start by looking at this image of Mata Nui crashing onto Aqua Magna in one of the comics:
The red line marks the point on the planet's circumference that is at 0 degrees from our perspective. By looking at the slope of the planet as it leaves our view, we can estimate the portion of the circumference between the image's edge and the red line to be ~22.5 degrees. Looking at a protractor or other measurable circular object for a second will convince you that a completely horizontal line from the 0-degree point to the point directly about the 22.5-degree point is 1/4 of a circle's radius, so we can assume that Aqua Magna's radius is 4x the distance between the red line and the image's edge. I have measured that length and found that it is 722 pixels, so Aqua Magna's radius is 2,888 pixels. In order to convert pixels to feet/miles, we can look at the yellow line, which is the length of the Great Spirit Robot's lower arm (it isn't much closer to the "camera" than the planet, so we probably don't have to worry about illusions of diminishing size). Since we know the height of the Great Spirit Robot (40 million feet), we can look at this picture
and compare the lower arm's length (blue line) to the height of the torso/head section, which is about half the robot's height (green line). Since the green line is 345 pixels-b (we're using the "pixels-b" mesurement because this image is a different scale than the other one) long and the blue one is 145 pixels-b long, we can calculate that 1 pixel-b = 20,000,000 (half the height of the robot)/345 or about 57,971 feet (10.98 miles). Now that we know that, we can determine that the lower arm is 10.98x145 or 1,592.1 miles long. Divide that by 44, the length in pixels of the lower arm in the first image, and we determine that 1 pixel is about 36.185 miles. Multiply that by 2,888 and we get 104,502.28 miles as the approximate radius of Aqua Magna. Now, the only thing we have left to do is look at this image
of the entire system in The Legend Reborn. The orange line (Aqua Magna's radius) is 6 pixels-c long and the purple one (Bara Magna/Spherus Magna's radius, they're the same because the space the other two fragments fill is just two holes on either side) is 56 pixels-c long, so Spherus Magna's radius is 28/3x as great as Aqua Magna's. 104,502.28 multiplied by 28/3 is ~975,354.613, so Spherus Magna's approximate radius is 975,354.613 miles. That is mind-blowingly huge. It's almost 11 times larger than the radius of Jupiter, meaning that it should be impossible for anything, robotic or organic, to live on it, assuming it has more or less the same composition as Earth. Even if we take into account the EP core and assume that EP has a very low density, the planet is still so massive that anything that set foot on it would be instantly crushed. Then again, though, this is Bionicle physics, so I think we can forgive it.
I apologize for any errors in my calculations that have gone unnoticed. I have checked it over thoroughly, though, so I doubt any major errors have been made. Regardless of the exact, precise size, though, my point that the planet should be too large for anything to live on still stands. I would appreciate any feedback that people have to give.
(Images taken from BS01 and modified with MS Paint.)
