Daily Archives: April 13, 2009

An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of the celestial sphere. read on…

As the Earth rotates from west to east around its axis once every 23 hours 56 minutes, the celestial sphere and all objects on it appear to rotate from east to west around the celestial poles in the same time. … Continue reading →