114
one must first decide whether the patches are permanent or variable’.
1
Though it is
clear which way he was leaning, he did not yet fall into a specific interpretation.
Only later, in 1862, would he definitively declare his belief on the subject.
Secchi measured the sidereal rotation period to be 24 h 37 m 35 s: this is 13 s too
long, but in 1864 Rudolf Wolf (1816–1893) in Zurich would use one of Secchi’s
drawings to redetermine the period to an accuracy considerably better than 1 s.
1 P.A. Secchi; quoted in Flammarion, The Planet Mars, p. 117.
Fig. 6.4 Two colour reproductions (June 3 and 14) of Secchi’s Mars drawings, published by
George F. Chambers (Chambers 1889). Here the seas are bluish, while the disk background – at
least in the upper illustration – is orange or reddish, but now faded
R. McKim and W. Sheehan
one must first decide whether the patches are permanent or variable’.
1
Though it is
clear which way he was leaning, he did not yet fall into a specific interpretation.
Only later, in 1862, would he definitively declare his belief on the subject.
Secchi measured the sidereal rotation period to be 24 h 37 m 35 s: this is 13 s too
long, but in 1864 Rudolf Wolf (1816–1893) in Zurich would use one of Secchi’s
drawings to redetermine the period to an accuracy considerably better than 1 s.
1 P.A. Secchi; quoted in Flammarion, The Planet Mars, p. 117.
Fig. 6.4 Two colour reproductions (June 3 and 14) of Secchi’s Mars drawings, published by
George F. Chambers (Chambers 1889). Here the seas are bluish, while the disk background – at
least in the upper illustration – is orange or reddish, but now faded
R. McKim and W. Sheehan