Pinwheel nebula Reference Libraries
Reflection Nebula -- In astronomy, reflection nebulae are clouds of dust which are simply reflecting the light of a nearby star or stars. The nearby star or stars are not hot enough to cause ionization in the gas of the nebula like in emission nebulae but are bright enough to give sufficient scattering to make the dust visible. The distiction between these two types of nebulae was done by...
- The navel or umbilicus.
- In Greek archaeology: A central boss, as on a shield, a bowl, etc.
- A sacred stone in the temple of Apollo at Delphi, believed by the Greeks to mark the 'navel' or exact center-point of the earth.