The phrase "In the Limelight" refers to someone who is the centre of attention. It is a fairly innocuous phrase but it has an interesting etymology (well I think).
Limelight - the process whereby lime is used to create light -was discovered by Goldsworthy Gurney in the 1820s.
He discovered that an intense white light is produced by heating a piece of lime in a flame of burning oxygen and hydrogen.
The idea was perfected by Thomas Drummond in 1825 which resulted in the Drummond Lamp.
This was widely used in 19th century theatres to illuminate the stage and was first used in a public theatre at Covent Garden in London in 1837. Clearly, actors who were the centre of attention on stage were said to be in the limelight.
A quote from the New York Times, July 1902:
"William S. Devery was in the limelight last evening. Tens of thousands of people of the district crowded the streets in the neighborhood and shouted the name of the ex-Chief of Police of New York."
This video show the brightness of limelight. [link]