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n 1995, two Swiss astronomers,
Michel Mayor and Didier
Queloz, researching at the
Observatoire de Haute-Provence
near Marseille, found a planet
orbiting 51 Pegasi, a sunlike
star 60 light-years away in the
constellation of Pegasus. This
was the first confirmed observation
of a true extrasolar planet, or
exoplanet—a planet beyond the
solar system. It was orbiting
a main sequence star, and was
therefore assumed to have formed
by the same process as that
which created the solar system.
Mayor and Queloz named the
new planet 51 Pegasi b, but it is
unofficially known as Bellerophon
after the hero who rode Pegasus,
the winged horse of ancient Greek
myth. Its discovery prompted a
major hunt to find more exoplanets.
Since 1995, several thousand
exoplanets have been found,
many in multiple star systems.
Astronomers now estimate that
there is an average of one planet
around every star in the galaxy,
although this is probably a very
conservative figure. Some stars
have no planets, but most, like
the sun, have several.EXOPLANETS
The discovery of 51 Pegasi b
marked the final milestone in a
process that has forced astronomers
to abandon any lingering notion
that Earth occupies a privileged
place in the universe.Copernican principle
In the 1950s, the Anglo−Austrian
astronomer Hermann Bondi had
described a new way for humans
to think about themselves, which
he called the Copernican principle.
According to Bondi, humankind
could no longer regard itself as
a unique phenomenon of central
importance to the universe. On
the contrary, humans should nowIN CONTEXT
KEY ASTRONOMERS
Michel Mayor (1942–)
Didier Queloz (1966–)BEFORE
1952 US scientist Otto Struve
proposes the radial velocity
method to find exoplanets.1992 The first such planet is
found, orbiting a pulsar and
not a main sequence star.AFTER
2004 Construction begins
on the James Webb Space
Telescope, which will be
able to image exoplanets.2005 The Nice model offers a
new idea for the evolution of the
solar system that places the
giant planets closer to the sun.2014 The construction of the
European Extremely Large
Telescope begins.2015 Kepler 442-b, an Earth-
sized rocky exoplanet around
an orange dwarf, is discovered.Michel Mayor Michel Mayor was born in
Lausanne, Switzerland, and has
spent most of his career working
at the University of Geneva. His
interest in exoplanets arose from
his earlier study of the proper
motion of stars in the Milky Way.
To measure this motion more
accurately, he developed a
series of spectrographs, which
eventually culminated in ELODIE.
The ELODIE project with Didier
Queloz was initially intended to
search for brown dwarfs—objects
that were bigger than planets
but not quite large enough to be
stars. However, the system wassensitive enough to spot giant
planets as well, and, following
their 1995 discovery, Mayor is
currently the chief investigator
at the HARPS program
for the European Southern
Observatory in Chile. His team
has found about half of all the
exoplanets discovered to date.
In 2004, Mayor was awarded
the Albert Einstein medal.Key work1995 A Jupiter-mass Companion
to a Solar-type Star (with
Didier Queloz)For more than 2,000 years,
people have dreamed of
finding other habitable worlds.
Michel Mayor