However this effect is negligible at the scale of accuracy that applies to a planetarium .
The celestial sphere , still used for teaching purposes and sometimes for navigation , is also based on a geocentric system which in effect ignores parallax .
This effect is negligible at the scale of accuracy that applies to a planetarium .
The celestial sphere , still used for teaching purposes and sometimes for navigation , is also based on a geocentric system which in effect ignores parallax .