132 
THE YOUNG SCIENTIST. 
The Heavens for October. 
BY BEKLIN H. WEIGHT. 
rriHE computations in the following are 
made for the meridian of New York city, 
and are expressed in mean or clock time: 
How to Find and Recognize the Major 
Planets and their Telescopic Appearance. — 
The major planets should always be looked 
for in the Zodiac, a belt extending 8° on each 
side of the sun's path. The only ultra-zodi- 
acal planets are the asteroids or minor plan- 
ets, which are invisible to the naked eye. 
The planets, unlike the stars, come into 
view at no particular season of the year, 
and are almost constantly changing their 
position among the stars, advancing or 
moving eastward, and apparently retro- 
grading or moving westward at different 
times. There are times, however, when 
they do not change their position, relative 
to the stars, for several days, owing to the 
fact that their motion in orbit is then in the 
direction of the line of vision. Hence, if 
upon observing a body in the Zodiac for 
several successive evenings, we find it 
changing its place with respect to the 
neighboring stars, it must be a planet or 
comet. This method will only apply to 
Mercury, Venus and Mars. The motion of 
Jupiter, Saturn and Uranus past the stars 
being too slight to be easily observed, while 
Neptune is invisible to the naked eye. 
There are nine major planets, including 
the newly discovered intra-Mercurial planet 
and the earth, and 186 minor planets. We 
will mention them in their order outward 
from the sun. 
Vulcan can only be seen during an eclipse 
of the sun, darkening the sky in its vicinity, 
and then only with the aid of a telescope. 
Mercury is so close to the sun that he can 
only be seen either during a solar eclipse 
and near greatest elongation, i. e. when his 
angular distance from the sun is greatest. 
Even when the elongation is greatest, he can 
not always be seen, owing to the fact that he 
is south of the sun part of the time, and con- 
sequently his altitude (perpendicular dis- 
tance above the horizon) at sunrise or sunset 
would be much less (for the same amount of 
elongation) than when north of the sun. 
When brightest, there are few stars that 
equal him in brilliancy. At a recent con- 
junction of Jupiter and Mercury, it wa» 
impossible for us to identify them by any 
difference in brilliancy. 
To the amateur telescopist Mercury pre- 
sents but few features of interest. A tele- 
scope of very moderate power will show his 
phases. His phase when brightest, is gen- 
erally very slightly more than a half-circle. 
He will be brightest Sept. 28, rising at 4h. 
27m. morn — Ih. 26m. before the sun, and 
6 minutes after the beginning of twilight — 
about 8° north of the sunrise point. He 
will be in conjunction with Venus Sept. 30. 
Their conjunction in right ascension occurs 
about 9 o'clock in the morning, and as 
Mercury has at that time the greatest ap- 
parent eastward motion in E. A., he will, 
when first seen, be east of Venus, Venus 
will be the brighter, and south of Mercury 
about one-fourth of a degree. He will not 
be visible again until December. 
Venus, to the eye, is the most beautiful 
of the planets, but when viewed with a 
telescope sadly disappoints the observer, 
especially if a high power be used and the 
instrument is not approximately achrom- 
atic. When brightest she may be seen 
with the naked eye at noonday. 
Any ordinary telescope or good opera 
glass will show her large crescent when 
brightest, and a little better instrument will 
show all of her phases. 
She is a morning star, remaining such 
until Dec. 5, when she reaches superior con- 
junction. Hence she now presents a large 
gibbous phase, or is nearly full, as we apply 
the term to the moon. She rises as follows: 
1st — 4h. 33m., morning. 
10th — 4:h. 57m., morning. 
20th — 5h. 21m., morning. 
30 th — 5h. 45m., morning. 
We have only mentioned the inferior 
planets, or those situated between the earth 
and sun. Next month we will conclude 
this description. 
Penn Fan, F., ^epi. 4, 1878; 
