Encyclopedia > Asterism

  Article Content

Asterism

Asterisms are patterns of stars seen in Earth's sky which are not official constellations. Examples include:

One ancient asterism, Coma Berenices, is now officially a constellation.


A second meaning of asterism is the optical phenomenon displayed by some rubies, sapphires, and other gems of an enhanced reflective area in the shape of a "star" on the surface of a cabochon cut from the stone. This is caused by small needles of rutile (titanium oxide) in the gem. The stars may have six rays or twelve. The rays are reflections from the the rutile crystal. Rutile can also cause a "cat's eye" effect in gemstones.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Shoreham, New York

... are 145 households out of which 38.6% have children under the age of 18 living with them, 74.5% are married couples living together, 8.3% have a fema ...

 
 
 
This page was created in 21 ms