Evening star. [volume] (Washington, D.C.) 1854-1972, 1927-07-31
THE STARRY SKIES IN AUGUST
a
Briiliancy of the Planets Venus, Mars
and jupiter.

The planet Venus. which has been
an object of wonder and beauty in the
western sky for many months, reaches
its greatest brilliance on August 3.
Its brightness, however. is but slightly
greater than it was last month. and
the fact that 1t now sets earlier and
must be seen nearer the horizon more
than offsets the advantage Of the
slightly increased brightness. 1t is
now moving slowly eastward, and
after August IS moves westward. so 1t
will soon be overtaken by the sun.
1t is already so near that its position
cannot be marked on figure /. This
matters little, however, as the planet
is so bright that it cannot be mistaken.
1t may be seen in the west in the eve
ming twilight or even in the day time
If it's direction is well known. BY the
end of the month it is too close to the
sun to be seen.
Mars is moving eastward, but not
so rapidly as the sun. and may be seen
with difficulty at the first of the
month, and by the end of the month
1t cannot be seen at all. Saturn, in
the constellation Scorpius, is now in
its best position. 1t is quite bright.
The fixed stars, Vega at A and Arc.
turus at B, and the planet Jupiter are
the only bodies shown which are
brighter. Below 1t at G is the red star
AntareS. The moon will be near Sat
urn on the evening of August 6. Jupi-
ter, which is the brightest planet after
Venus, and brighter than any or the
fixed stars, appears on the eastern
horizon and will now supplant Venus
as an object of attention. The planet
Uranus is just on the limit Of naked.
eye vision, and is not only difficult to
see but must be selected from a great
number of stars of about the same
brightness If it is to be identified. /
suppose very few try to see the planet
with the naked eye. At times 1t may
be near a brighter star which is easily
identified, and If one knows this It Is
easier to find the planet. 1t happens
that Uranus is now near the planet
Jupiter. It will be five-sixths Of a de.
gree directly north of it on August
and at about the same distance away
up to that time. There are no stars
as bright as Uranus in that vicinity
to confuse.
Uranus probably cannot be seen
with the naked eve with the brilliant
Jupiter so near, but 1t may be seen
easily with opera glasses. In this con.
nection, 1t Is well to remember that
the moon is about half a degree in
diameter. Mercury may be seen in
the morning twilight for few days
about August 8.
The Moons Phases.
= There are many who do not under
stand the cause Of the phases Of the
moon, although they have observed
them for many years, so brief expla-
nation will now be given. The moon,
like the earth and other planets, has
no light Of it's own, but shines only
because the sun shines on 1t and be.
cause it reflects that light. Conditions
are represented in figure 2. The fig
ure is not drawn to scale. The moon
is about a quarter as large as the
earth in diameter and is 80 times the
diameter of the earth from it. The
sun, is 3S9 times as far away as the
moon. The rays of the sun illumi-
nate half Of the earth at one time and
that half of the earth has daylight.
The dust in the atmosphere reflects a
little light to places a little beyond
the daylight half. This section has
twilight. 1t is represented in the fig
ure by the shaded section. The rest
OF the earth has night. The half of
the moon toward the sun similarly has
daylight and the other half has night.
AS there is no appreciate atmosphere,
there is no twilight zone on the moon.
The figure shows arrows on the left
to indicate the rays of light from the
distant sun. These illuminate the
half of the earth and of the moon on
that side: The moon is shown freight |
positions in its orbit thus illuminated,
AS there is no appreciate atmosphere,
to the plane of the orbit. The moon,
however, is viewed from the earth and
the observer can see but half of it at
one time, the half toward him.
Through the moon in each nositiou ia
drawn a diameter extending slightly
beyond it. marking the boundary of
: the half which he could see if 1t were
illuminated. In the position marked
new moon" none of the half toward
the earth is Illuminated, and hence
the moon is invisible OF course it
could not be seen in the direction of
the sun anyway. When the moon has
moved to the next position shown.