The third quark is called STRANGE. That name had already been associated
with the K mesons because their long lifetimes seemed a "strange" or
unexpected property. (K mesons contain strange quarks.)
There are six flavors of quarks. "Flavors"
simply means different kinds. The two lightest are called UP and DOWN.
The third quark is called STRANGE. That name had already been associated
with the K mesons because their long lifetimes seemed a "strange" or
unexpected property. (K mesons contain strange quarks.)
CHARM, the fourth quark type,
was named on a whimsy. It was discovered in 1974 at the Stanford
Linear Accelerator Center in the particle they called
(psi) and simultaneously at Brookhaven
National Laboratory in what they called "J".
The 
is a charm-anticharm combination
(
).
The fifth and sixth quarks were originally called truth and beauty, but even physicists thought that was too cute. Now they are called TOP and BOTTOM (still t and b.)
The bottom quark, in a bottom-antibottom
(
) combination called Upsilon
(
), was first observed at Fermi
National Laboratory in 1977.
The sixth flavor of quark, top, is the most
massive quark. It is about 35,000 times more massive than the up and
down quarks that make up most of the matter we see around us. On
March 2, 1995 Fermi National Accelerator Laboratory announced the
discovery of the top quark.
Of the six quarks predicted to exist by current
scientific theory the top quark was the last to be discovered.