big science and the transits of venus 137
required state sponsorship, making naval voyages the Big Science of the
era. A useful early example of seafaring Big Science is provided by the
international races to observe the transits of Venus in the eighteenth and
nineteenth centuries.
The Transits of Venus: The First “Space Race”
Transits of Venus (TOVs), in which Venus travels between the Earth and
the sun and is seen as a dot crossing the face of the sun, occur in inter-
vals of 105. 5 years, 8 years, 121. 5 years, and 8 years. The last TOV took
place on June 6 , 2012 , and did not attract much international attention.
This was not the case in the eighteenth and nineteenth centuries. Four
transits took place during this period: June 6 , 1761 ; June 3 , 1769 ; Decem-
ber 9 , 1874 ; and December 6 , 1882. These transits became the focus of
unprecedented international scientific competition accompanied by in-
tensive media coverage, generous governmental funding, and globetrot-
ting expeditions. As many as 150 observation stations were established
by eight different countries for the 1769 transit, leading historian Harry
Woolf to conclude that “no other particular scientific problem in the eigh-
teenth century brought so many interests to a single focus” (Woolf 1959 ,
23 , 182 – 87 ).
The interest in the TOV arose from what British Astronomer Royal
George B. Airy ( 1801 – 92 ) coined “the noblest problem in astronomy”—
the desire to determine the average distance between the Earth and the
sun (Jayawardhana 2004 ). This distance, the mean radius of the Earth’s
orbit, serves as the natural constant of physical astronomy, the astronomi-
cal unit, used for calculating the relative position of all members of the
solar system (Woolf 1959 , 3 ). Scientists have grappled with this problem
since the days of ancient Greece, refining their measurements but never
reaching a satisfactory estimate.
The first to realize the importance of the TOV as an instrument for
solving this problem was Edmond Halley ( 1656 – 1742 ). In 1716 Halley
published a paper suggesting a method for calculating the astronomical
unit based on transit observations: if two or more observers, separated
widely at latitude, measure the time it takes Venus to cross the sun, the
difference between the timing at the various locations would provide as-
tronomers with the solar parallax from which the astronomical unit can
be easily deduced. Halley left detailed plans for his successors, ensuring
