Evening star., 1952-11-28
Two Island GuIoxies
Are Crashing Heod-on
Each Compares in Size
To Milky Way System
By Thomos R. Henry

By Thomas R. Henry
The most stupendous crash in crea.
ton is now in progress.
Two island galaxies, each comparable
in size to the Milky Way system with
its hundred billion or more stars, of
which the sun is one of the more in
significant, are crashing head-on at q
speed of thousands of miles second.
These galaxies are so far from the
earth that their light requires several
million years to cross the void, but still
the force of the crash is being felt in
the Milky Way.
This is the latest revelation of the new
radio astronomy. For the past five
years astronomers have been locating
"hot spots" in the Milky Way system by
their intense emission of short radio
waves. Approximately 100 of these now
are catalogued.
One Of the two or three most intense
Of the hot spots is in the constellation
of Cygnus, the Swan, in the northern
heavens. best known from the six-star
Northern Cross and the bright star
Deneb, 5000 times more luminous than
the sun.
But no object could be found in Cyg-
nus which could account for this. The
particular part of the heavens from
which the radiation came was empty Of
any but ordinary stars. But giant tele-
scopes now look through CygnuS far
beyond the Milky Way system itself,
millions of light years into supposedly
void space. But this is, after all, full
of galaXies, each as big as the Milky
Way, each separated from the others by
a million or more light years.
Now, it has been observed by astron-
omers Of the Mount Wilson Observatory
of the Carnegie Institution of Washing
ton, two of these galaxies appear to be
merging at approximately the focus Of
the angle from which the intense radio
emission is being received. Presumably,
the crash already has been in progress
for some time. Whatever happened, Of
course, happened several million years
ago for the galaxies' light has taken
that time to reach the earth.
Observation Locally Discussed.
1t is not yet certain that the apparent
merging of the galaxies can be inter-
preted as a crash and there has not yet
been any official publication Of the OBJ
servation, although it has been discussed
at meetings of astronomers, following
lecture on radio astronomy before the
Washington Academy of Sciences.
It Is highly unlikely. it was pointed
out in the discussion, that the crash OF
the galaxies means that many of the
individual stars are smashing into Zach
other. Presumably the stars of both
galaxies are as widely dispersed as those
Of the Milky Way system. The sun and
it's planets are in fairly populous part
of this system, yet the nearest star.
Alpha Centauri, is so far away that its
light, crossing space at a speed of 1885,
900 miles second, requires about five
years to reach the earth. So, except for
an occasional accident, the stars of the
crashing galaxies may be expected to
pass between each other.
But, it now is known, the space be-
tween the stars of this system is not en-
tirely empty. Rather it is filled with
very tenuous dust. perhaps consisting
largely of atoms of hydrogen. This dust
is infinitely more tenuous than the finest
vacuum ever attained on earth-but it
still is there, lot OF 1t.
The gas particles between the stars
of the two galaxies are smashing to-
gether at enormous speeds, according to
the Interpretation brought out in the
discussion. Thus enormous temperatures
are generated-although very probably
astronomers on any planet OF any star
in either of the crashing galaxieS are
not aware of the fact. These tempera-
lures result in the generation Of radio
waves with such intensity that they
cross the great void between the uni
verses and rise above the background
emission of the Milky Way system to
confound observers on earth.
Double Galaxy May Result.
A galaxy crash, if this actually Is what
Is happening, Is a new phenomenon In
nature which probably never would have
been observed except for the impetus
given by search for the radio source.
At the best 1t must be an extremely rare
event, because all other observations show
the galaxies moving away from each
other at enormous speeds. The end re-
suit may be to form double galaxy, or
the tive may pass completely through
each other.
otherwise only twopoint sources for
the more intense radio emissions have
been identified. One Of the so-called
Crab nebula comes from a point in the
heavens where a titanic star explosion.
a supernova, was reported by Chinese
astronomers in the 18th Century. There
is no visible object there now.
Another point source has been as
sociated with thick clouds Of hydrogen.
Otherwise the radio stars" more and
more of which are being located. still
constitute a complete mystery.