56 
THE GUIDE TO NATURE 
Ursa Major (the big dipper), so use- 
ful for indicating the positions of other 
celestial objects; now lies low in the 
northwest and will be low in the north 
during the winter months. The great 
square in Pegasus in the east may well 
be used now as a reference constella- 
tion. 
^ ^ ^ ^ 
The Planets in September. 
Mars is the only planet now visible 
to the naked eye. Its positions at the 
beginning and close of the month are 
shown on Figure i. Mars passes An- 
tares at C September 17. Mars will 
then be brighter than Antares and a 
little less than three degrees north of it. 
This conjunction of these objects is in- 
teresting because of the fact that the 
name of the star Antares is composed 
of the two Greek words anti and Ares, 
meaning the rival of Mars. The name, 
no doubt, is based upon the fact that 
both subjects are of a decidedly red- 
dish color. Mars is a planet — that is, 
a body moving in an ellipse about the 
sun and shining because it reflects the 
sunlight which falls upon it. On Sep- 
tember 17 it will be 120.000.000 miles 
from the earth. It is about a seventh 
as large as the earth. The sun is 8,- 
700,000 times as large as Mars. An- 
tares is a fixed star whose distance 
from us is too great for accurate meas- 
urement. but we can say that its dis- 
tance is at least millions of times as 
great as that of Mars and that it is a 
body many thousand times as large as 
the sun and many billions of times as 
large as Mars or the earth. The motion 
of Mars is now rapid and a few nights’ 
interval in observation shows clearly 
that it has moved. The observations 
should be made in the early evening 
before the planet is too low in the sky. 
Uranus, which is now nearly as close 
to the earth as it ever is, is in the posi- 
tion in Aquarius shown on Figure 1. It 
is of the sixth magnitude, too faint to 
be seen with the naked eye but easily 
seen with opera glasses. It looks like 
a faint star. Saturn becomes a morn- 
ing star on September 7. Venus is still 
too near the sun to be seen, but by the 
end of the month it will set an hour 
and a half after the sun and can then 
be seen dimly in the twilight. It will 
be conspicuous later in the year. 
The Milky Way. 
Those interested in the sky will find 
it very interesting and profitable to 
select a very clear and moonless night 
to verify the following description of 
the Milky Way. We shall begin in 
the south. The description follows that 
of Herschel. The Milky Way subdi- 
vides at Alpha Centauri (below the 
southern horizon) into two branches. 
One large branch cuts the southern 
horizon in a complicated series of in- 
terlaced streaks and masses which 
cover the tail of Scorpio and terminates 
in a vast and faint effusion over the 
whole extensive region occupied by the 
eastern part of Ophiuchus, extending 
northward to thirteen degrees south of 
the Equator, beyond which it cannot 
be traced, a wide interval of fourteen 
degrees free from all appearances of 
nebulous light separating it from the 
great branch on the north side of the 
Equator, of which it is usually repre- 
sented as a continuation. 
The other branch from Alpha Cen- 
tauri collects in Sagittarius into a vivid 
oval mass about six degrees in length 
and four degrees in width, so exces- 
sively rich in stars that a very moder- 
ate calculation makes their number ex- 
ceed 100,000. 
Northward of this mass the stream 
has its course rippled by three deep 
concavities separated from each other 
by remarkable protuberances, of which 
the larger and brighter in Aquila forms 
the most conspicuous patch in the 
southern portion of the Milky Way 
visible in this latitude. Crossing the 
equator it runs in an irregular, patchy 
and winding stream through Aquila 
and Sagitta up to Cygnus. At Epsilon 
Cvgni its continuity is interrupted and 
a very confused and irregular region 
commences, marked by a broad, dark 
vacuity sometimes called the “Northern 
Coal Sack,” occupying the space be- 
tween Epsilon and Alpha Cygni, which 
serves as a kind of center from which 
three great streams diverge. One is 
the branch we described. Another, very 
vivid and conspicuous, runs off through 
Beta Cygni in a southerly direction 
almost to the Equator, where it loses 
itself in a region thinly sprinkled with 
stars. 
This is the branch which, if contin- 
ued across the Equator, might be sup- 
posed to unite with the great southern 
