BAIEN compared the concentric sphere to a ball and wrote the celestial sphere was the biggest ball and compared the radial line to a chestnut-burr. However, the fireworks that radiate from the center after an explosion is a good example as a metaphor for both.
The top letter "外" which is outer the figure means out space of the celestial sphere. The center letter "中" means the center, "内" means the inner, "外" means the outer space in the sphere. "上" and "下" means upper and lower.
BAIEN knew the existence of gravity in the second half of the middle Edo period. If we think that the center of left figure is of the earth's, we have seen the celestial sphere from the Heavenly Arctic.
It would be surprising if Baien saw the following site. But he had only a brush, paper and compass from the Edo period.