Introduction
In an 1833 paper appended to his fifth catalog of double
stars, the British astronomer John Herschel offered a
rather extraordinary suggestion. Commenting on his catalog
of over two thousand double stars (over half of which
he had discovered), he singled out a bright star in the
constellation Ursa Major with a dim companion that had
not been previously noticed. In the case of this type of
double star – a bright primary star with a very minute
companion – he suggested that such dim companions were
‘in some instances possibly shining by reflected light.’1 He
then went on to name five other double stars of this type
and hinted that there could be more. In other words, one of
the leading astronomers of the nineteenth century was
suggesting that the dim companions observed in some
double star systems were in fact planets.