Normally Earth would be written as ๅฐ็ chikyuu, where ็ means 'ball/sphere'. But here it's been written as ๅฐ็ chitama, where ็ also has the meaning of 'ball/sphere'.
Actually, Lalaca, ็ can be read tama as well. I'm sure you can invent any sort of silly reasons for this picture, including (from Chen's point of view) being too stupid to read it correctly, or (from the author's view) somehow tying it into the fact that โจ is also read kyuu.
Additonally, the author writes that he was unable to draw the earth very well, so it just became blue outside of Japan. Also, I didn't notice when I posted this, but it's actually a color of a black and white picture from watarun. I suppose I'll add that tag as well.
Silly me, you're so right about the pronunciation. Always end up sticking with the most often used yomi in my head and thinking of nothing but that until way later.
Specifically, this is the pose for the title screen during the first 2 opening songs in Gundam Seed. The last 2 opening songs had a similar but different angle.