18 
NATURE FOR ITS OWN SAKE 
The zodi- 
acal light. 
Moonrise, 
first twilight is, however, sometimes followed 
by a second glow; and after this has passed 
there is occasionally another hght seen in the 
western sky called the zodiacal hght. This 
usually forms itself in the shape of a pyramid, 
with its base toward the horizon and its apex 
extending zenithward along the track the sun 
has traversed. It is a pale nebulous light, like 
that of the star clusters called the Milky Way ; 
it appears more frequently in the tropics than 
in the temperate zones, at dawn as well as at 
twilight, and is often referred to as the ‘“ False 
Dawn” and the “ Wolf’s Tail.” The cause of 
its appearance has not yet been satisfactorily 
explained. 
No sooner is the sun gone (at times before it 
is gone) than the moon comes up beyond the 
eastern hills, at first rising slowly and then sud- 
denly bursting into view. Iftheday has been hot 
and dry the face of the disk is red or deep or- 
ange, abnormally large in appearance, and often 
bulged and misshapen as regards its circle. We 
are looking at it through that same lower stratum 
of dense air which has been rising all day from 
the earth, and is still rising though the sun has 
set. It is the dense air that gives the abnormal 
size and the ruddy color. As the orb rises 
