  In 1977, while Apple II and Atari computers were being sold, a tiny dot was
observed in an inconvenient orbit. The minor body 1977 UB, to be named (2060)
Chiron, with an orbit between Saturn and Uranus, became the first Centaur, a
new class of minor bodies orbiting roughly between Jupiter and Neptune. The
observed overabundance of short-period comets lead to the downfall of the Oort
Cloud as exclusive source of comets and to the rise of the need for a
Trans-Neptunian comet belt. Centaurs were rapidly seen as the transition phase
between Kuiper Belt Objects (KBOs), also known as Trans-Neptunian Objects
(TNOs) and the Jupiter-Family Comets (JFCs). Since then, a lot more has been
discovered about Centaurs: they can have cometary activity and outbursts,
satellites, and even rings. Over the past four decades since the discovery of
the first Centaur, rotation periods, surface colors, reflectivity spectra and
albedos have been measured and analyzed. However, despite such a large number
of studies and complementary techniques, the Centaur population remains a
mystery as they are in so many ways different from the TNOs and even more so
from the JFCs.
