Editing Celestial sphere (section)

=== Determining location of objects ===
The celestial sphere can thus be thought of as a kind of astronomical [[shorthand]], and is applied very frequently by astronomers. For instance, the ''[[Astronomical Almanac]]'' for 2010 lists the apparent geocentric position of the [[Moon]] on January 1 at 00:00:00.00 [[Terrestrial Time]], in [[equatorial coordinate system|equatorial coordinates]], as [[right ascension]] 6<sup>h</sup> 57<sup>m</sup> 48.86<sup>s</sup>, [[declination]] +23° 30' 05.5". Implied in this position is that it is as projected onto the celestial sphere; any observer at any location looking in that direction would see the "geocentric Moon" in the same place against the stars. For many rough uses (e.g. calculating an approximate phase of the Moon), this position, as seen from the Earth's center, is adequate.

For applications requiring precision (e.g. calculating the shadow path of an [[eclipse]]), the ''Almanac'' gives formulae and methods for calculating the ''topocentric'' coordinates, that is, as seen from a particular place on the Earth's surface, based on the geocentric position.<ref>''Astronomical Almanac 2010'', sec. D</ref> This greatly abbreviates the amount of detail necessary in such almanacs, as each observer can handle their own specific circumstances.