Crab Nebula
The Crab Nebula was an interstellar gas cloud.

In 2365, attempting an amusing anecdote with the aim of entertaining Captain Picard and Lwaxana Troi, Lieutenant Commander Data explained how he was able to precisely calculate the distance between the Crab Nebula and the Omicron system. He accomplished this by multiplying the square root of  with nine to the third . ()

External link 
 

de:Krabbennebel
es:Nebulosa del Cangrejo
Nebulae