El Paso herald. (El Paso, Tex.) 1901-1931, 1917-06-28

! dAAEGuN AOAAlEG0AI- OAA
/ the following evening a very fine
hairIike tail about as long as half
/ the diameter Of the moon was dis
! cernible, and on the Sd OF April ii
/ had developed into one Of the finest
/ objects that I have ever seen in the
4 sky with a very fine starlike nue.
/ leus Of about the 4th magnitude sur
I rounded by a delicate coma some
/ what necked in and prolonged into
I beautiful tail about a degree long,
or twice the diameter Of the moon
l This comet has now passed the sun
/ and has become a morning object
/ On the 14th OF April it was about 81
minutes west of the sun, increasing
I this distance on the 22d to about one
hour and % minutes, passing at the
same time in declination south to the
| equator to g degrees. While pass
/ ing about the sun at distance OF
I only about II million miles il &C
quired a speed of IS miles q second,
( Of $500 times the speed Of the fastest
Z express train In case of Wots
comet the velocity at perihelion viii
/ be only 20 miles a second; in the
case Of Halley's comet il vas about
/ So miles per second
Comets Head Contracts.
A very peculiar feature of comet
+ is the contraction of its head as il
nears the sun, accompanied by the
constant formation and dissipation OF
a tail The appearance of a tail only
/ being always away from the sun is
explained by astronomers in the fol-
/ lowing way: The sun, besides having
an attraction for the particles OF the
comets head, also exerts repulsion
on ths same designated as light
pressure" The amount OF attraction
due to gravity, as is well known.
depends directly on the masses OF the
particles attracted which again de-
pends, assuming the density not to
I 81 r-n1rrrna Of the
ticles; light pressure, on the other
hand. being somewhat analogous TO
the pressure of wind, is proportional
to the area the particle exposes As
suming the particles OF the comets
head to be spherical. il is known from
elementary principles OF geometry
that If the diameter is diminished the
volume diminishes as the cube and
the area diminishes as the square OF
the diameter; so there must be some
particles Of such size that light pres
sure depending on the exposed area)
coming from the sun has a greater
effect in repulsion than gravity (de-
pending on the volume) has in at
traction: hence those particles are
driven off and form the tail Of the
comet. Gravitation and light pressure
have thus a sitting effect upon the
particles making up the head OF the
comet; the larger ones being re-
tanned and the smaller ones driven /
off. This may also to some extent
explain the contraction of the head
as the comet nears the sun Comets
tails then are constantly formed, dis /
sipated into space and reformed AS
the comet passes away from the sun. /
light pressure, OF course, gets less and ]
less and the comet loses its lovely ap- I
pendage. The particles being. as IL
were, blown away from the head 1
tail is always directed away from /
the sun
VOLTS Comet Is Slow.
VOLTS comet seems to be making /
very slow progress as TO brightness |
IN March it was just visible in our
nine-ineh equatorial, but we stin
hope II may become q good naked !
eye object during the summer when /
il fingers during that season and fall J
in practically the same region OF the /
sky, having only a slow southwark
movement
On April 23d, Schaumasse at Nice |
discovered a new comet % 1e1D NOV (
ing slowly northwestward and visible
in a small telescope. It is now In
the constellation OF Andromeda, (May
18th Right Ascension 0 hrs % min
utes and declination plus IS degrees
80 minutes). This morning the writ
e. saw IL quite conspieuOusly in the
g. finder and in the g. fine well
rounded patch OF about 2-S' diameter
well condensed toward the center was
seen: the condensation was not star
like, but having diameter Of IL TO
/. The comet passes periheHon to-
day. coming within about Il million
miles of the sun The comets orbit
is inclined about $50 degrees to the
plane Of the ecliptic- No tail forma-
tiou was visible.
VOLTS comet. seen on the same
morning. is still rather insignificant
IL will have TO begin soon in order
to come up to the expectations OF its
friends, the star gazers- Mellishs
and Schaumasse's comets have GER
tainiy done very much better
The Planets For July.
Mercury will be a morning star
until July u. when il passes TO the
evening sky, but will be so far south
OF the sun that it will set shortly
after and probably will not be visible.
Venus will become an increasingly
interesting object in the western eve
ming sky during July. 1t viii set
about a half hour after the sun during
the month
Mars is in the morning sky, rising
at a m. on the LIST and at a. n. on
the S1st.
Jupiter is 4 morning star during
July near the Pleiades. rising at
q m. on the 1st and about midnight
on the 31st-
Saturn is still in the evening sky
in Cancer. setting about an hour
after the sun on the 1st. but will be
too near the sun to be seen by the
last of the month.
Uranus will rise in the east about