It's worth remembering that speculations about the
possibility of planets orbiting other stars goes
back a very long time.
Giordano Bruno said in the sixteenth century in
space, there are countless constellations, suns and planets.
We see only the suns because they give light.
The planets remain invisible for they are small and dark.
There are also numberless earths circling around their suns.
Well unfortunately, Bruno is burned at the stake
in 1600 not just for his astrobiological speculations
but also because he did other things that irritated his religious superiors.
But nevertheless, his speculations about the possibility of planets
orbiting other stars, even earthlike planets was truly remarkable.
The search for planets around other stars really
became an empirical science in the late twentieth century.
In 1992, 2 radio astronomers announced the discovery of 2 planets orbiting a pulsar,
a rotating neutron star.
And in 1995, Michelle Meyer and Didier Queloz
of the University of Geneva announced the first definitive
detection of an exo planet orbiting a main sequence
star, a G type of star called 51 Pegasi.
These discoveries ushered in the era of the search for extra solar planets.
And now many of these planets are known and continue to be discovered everyday.