El Paso herald. (El Paso, Tex.) 1901-1931, 1911-01-28


dian two hours earlier every month.
The bright star Sirius is on the meri-
dian at 10 D. m. on the first Of Febru-
airy, on the first of March it will be
on the meridian at s p, m The same
thing holds good for all the fixed stars
and consultations.
The Sky Maps Purpose.
The Sky Map as printed above is an
attempt to represent the blue vault of
heaven by drawing on a piece of
paper. The heavens form a sphere. It
IS found impossible TO correctly repre-
sent on a plane without distortions
the relative distances and directions
on a sphere. Various attempts have
been made, but the one given above is
about the most satisfactory. AS the
readers well know, the Sky Map gives
the position of the heavens at 9 D. m.
on the first of the month. At the end
Of the month the stars will have the
same position two hours earlier. at Z
D. ms and half through the month, on
the 18th, at s p. m. The planets or
wandering stars" change their posi-
tions continuously among the fixed
stars. and these changes cannot be
foretold except as the result of calcu-
latfon.
Solar and SidereaI Days.
If all sidereaI days are equal to each
other, are not all solar days likewise?
Solar days. though longer than side
real days, could be equal IN length to
each other only II the sun moved uni
formly among the stars in circle of
right angles to the axis of the earth.
This circle in the sky is the equator
But the sun does not move In the
equator but IN the ecliptic, and with
q motion in this latter circle which is
not uniform Hence e double cause ex-
lists which alters the intervals of time
between successive transits of the
sun across the meridian, and which
we call apparent solar days As a
matter Of fact, a solar day at one time
Of the year may be as much as so
seconds longer than at another time
OF the year.
It is manifestly impossible to manu-
facture a clock which would keep
track with the actual time kept by the
sun, and It became. necessary TO IN
vent a uniform sun time that a clock
could follow. Consequently, the aver
age, or the mean of the lengths of all
the apparent solar days for the year
was taken, and this was called the
mean solar day" An imaginary sun
called the mean sun" is supposed to
of time. The real sun does not give
directly the time of noon as kept by
our clocks. Clock noon at any OBJ
servatory differs from apparent
noon" when the actual sun is on the
meridian, by an amount known as the
equation of time" which may be as
great as 1e minutes.
Would Always Be Wrong.
A clock which regulates the sun"
would always be wrong. Accurate,
mean solar time may be determined
by the astronomer from observations
on the sun, but strange as it may
seem, a great observatory like the
United States Naval Observatory Of
determines its precise So
lar time by observations on stars. But
it will be impossible to go farther
into this interesting topic at present.
The Consultations.
The stars during the early evenings
In February present the most brilliant
quarter of the whole heavens. Every !
one can find the Pleiades, the Hyades
with Orion farther south, and bright |
Sirius still TO the east Orion is the |
warrior with the great club lifted to !
meet the charge of the onrushing |
bull. The three stars in the middle |
Of the constellation form the belt the |
three below the sword scabbard. The |
middle of these latter three IS the !
we'll known nebula family visible to |
he naked eye In a small telescope /
IN a clear moOnless night, this pre-
sents fine object. To be seen in all
is grandeur it is necessary to view a
ong exposure photograph which
shows much more than can be seen
even in the most powerful telescope /
The curving beauty of the wisps Of
lebulosity is marvelous9y beautiful
The Planets.
The month opens with Mercury at
greatest elongation west of the sun, |
md a morning star, but it will be low
Town in the sky and difficult TO find.
Venus is an evening star readily
-isible to anyone who cares to look
or 1t. It may be seen low down in
he southwest shortly after sunset On
he first Of the month Venus sets one
our and 20 minutes after the sun, and