Here you CANNOT see the Romulan War Bird in front of some open star clusters
Here you CANNOT see the Romulan War Bird in front of some open star clusters

Fun post for Friday.

Researchers at Nanyang University demonstrate the refractive qualities of Calcite to make a post it note ‘disappear.’

[youtube=http://www.youtube.com/watch?v=U5APMyTGrFg]Researchers at Nanyang University demonstrate the refractive qualities of Calcite to make a post it note ‘disappear.’
Erasmus Bartholin was the first to note the double refraction of iceland spar (Calcite) in 1669.  You can get his  Experimenta crystalli Islandici disdiaclastici quibus mira & insolita
refractio detegitur
 
as a free ebook.

Isaac Newton also experimented and reported on the phenomenon.

But the folks at Nanyang University got it posted to Youtube

Obvious applications include defense, organized crime, smuggling, and advertising.
Open clusters