Product dimensions measured on a flatly laid out product.
Tip: measure an item of clothing at hand to compare.
The celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the celestial equator and the celestial poles. The celestial sphere is a very practical tool for positional astronomy.
Tags: Astronomy, Celestial sphere, Earth, Jupiter, Mars, Mercury, Neptune, Saturn, Solar System, Sun, Uranus, Venus, gas giants, geek, ice giants, nerd, nerdvana, nerdvana shirts, terrestrial planets