ON THE LIGHT OF THE MOON AND OF THE PLANET JUPITER. 225 
respects the distribution of light over its disc. Mars, when near its full phase, has a 
nearer resemblance to the Moon. 
In the course of the observations upon the quantity of moonlight received from the 
different phases, comparisons were also made, by the same method, upon Jupiter and 
Venus, furnishing the following results: — 
Brightness of Jupiter at mean opposition ` 1 
Brightness of mean full Moon ~~ 6480 
Brightness of Jupiter at mean opposition — 1000 
Brightness of Venus at greatest brilliancy — 4864 
The subject next discussed has been the albedo, or reflective capacity, of the Moon 
and Jupiter. That of the Moon is represented by the expression 
y — £5193 
8 
S being the ratio of sunlight to full moonlight at the earth. If we assume the 
mean between Bouguer's and Wollaston's determinations, we have very nearly, — 
, 
S = 550000. 
A new determination of this proportion, communicated in a subsequent memoir, has 
given the value 
: S = 477530. 
‘It appears, therefore, that the Moon absorbs about ten parts out of every eleven 
of the light incident upon it; that is, we have | | 
St 
| ae 
The albedo of Jupiter compared with the Moon was found to be 
Kl dr. 
p 
Hence we arrive at the singular conclusion, that the albedo of Jupiter is 
pcm a es 1.04, 
much exceeding that of the whitest opaque substance known. Its optical brilliancy 
presents therefore an anomaly similar to that recognized in the chemical rays, for 
we have for the latter, — 
Chemical albedo of Moon — 1 
Chemical albedo of Jupiter 14 
