Over 400 years after the death of Danish astronomer Tycho Brahe, scientists in Prague are preparing to exhume his body. Was Europe's most renowned scholar poisoned with mercury? A Danish scholar claims to have decoded the murderer's diary.

Walls of people formed to watch a funeral procession pass through the streets of Prague on Nov. 4, 1601. A herald carrying a billowing damask flag was followed by 12 imperial guards bearing a coffin covered with black satin. The man inside wore a full suit of armor.

Tycho Brahe, the brilliant observer of the stars in the Renaissance, was being carried to his grave. The scholar had systematically measured the sky, paving the way for science in the modern age. In 1573 he became the first person to describe a supernova, the explosion of a star.

His assistant, Johannes Kepler, praised him as a "phoenix" of astronomy. Brahe simply compared himself to the "Messiah."

He was also a bon vivant -- a member of the Danish aristocracy, and master of his own island. A biographer called him an "indestructible, blustering social being with an enormous appetite for food and wine."

So what killed this tycoon of the heavens?