1876.] 
Sidereal Astronomy. 
69 
governed by a primary blue sun, and receiving at the same 
time the more distant illumination of our adtual sun ; secondly, 
three immense worlds, Saturn, Uranus, and Neptune, turn- 
ing round a double sun, one white and the other blue ; 
thirdly, four moderately-sized globes, Mars, the Earth, Venus, 
and Mercury, turning round the white sun, but illuminated 
at certain times during the night by a second blue sun. Let 
us now endow the sun with a red light ; we thus reproduce 
one of the most common types amongst double stars coloured 
with complementary shades. Let us examine for an instant 
what a succession of phenomena would be produced by the 
modification which we have thus made in the sun and in 
Jupiter. 
Let us imagine the Earth as it would be at the time of 
Jupiter’s opposition, that is to say, placed just between the 
sun and Jupiter. In this position, there would be no 
night for any point on the Earth ; whilst the red sun shone 
on one side of the Earth, the blue sun would shine on the 
other; there would thus be a red day on one hemisphere 
and a blue day at the other, and all the meridians of the 
globe would pass successively in twenty-four hours through 
these two kinds of day, distributing to all the countries of 
the globe twelve hours of red day and twelve hours of blue 
day, with no night. 
But our blue sun would not itself remain stationary in 
space ; it would slowly turn round the red sun ; soon it 
would rise before the other had set, and would appear above 
the eastern horizon when the celestial ruby had not yet dis- 
appeared. The blue day would then succeed, but the 
sapphire sun not setting in its turn before the rising of its 
shining rival one, we should have a night for a few moments 
ornamented with two aurorae boreales of a new kind, the one 
reddish at the east, the other bluish at the west. The dura- 
tion of this night would augment from day to day, and at 
the same time as the double day illuminated by the two 
suns at a time, the blue hours and the red hours diminishing 
in the same proportion. Ultimately, and at the epoch cor- 
responding to the conjunction of Jupiter, the blue sun would 
approach the red sun, and there would be neither red nor 
blue day, but a double day followed by complete night. 
The light of the double day would be formed naturally by 
the union of the colours of the two suns. It would be 
violet, but might be quite white, if the colours were com- 
plementary. Carried on always by its proper movement, the 
secondary sun would pass to the west of the first, and would 
soon produce blue mornings, followed by a white day, or a 
