Evening star., 1953-07-27
Moon Moy Hit Earth
In 100 Billion A. D.
Collision Also Possible
With Asteroid Any Day
By Thomas R. Henry

The earth might be destroyed any
day, but man has little need to worry
for another 81 billion years.
Then the moon probably will break
up and its fragments will fall in show
ers all over this planet.
Meanwhile about the worst that can
happen is collision with one of the
several hundred asteroids, planets no
bigger than fair-Sized mountains cir
cling around the sun, whose orbits
happen to cross the earth'S orbit.
This is the prediction of DR.. Albert
G. Wilson of the Mt. Palomar Observa-
tory staff in answer to some current
predictions of imminent disaster.
Within the past few years, he says in
bulletin issued by the California Insti-
tute of Technology, about a dozen new
asteroids have been found whose orbits
cross that of the earth. One, in 1887,
missed a Smash-up by mere 100000
miles.
Devastating Collision.
If there are no more, it has been
calculated that one of these will hit
the earth. moving at speed of about
thirty miles a second, about once in
30 million years. 1t is highly probable,
however, that the actual number runs
into the hundreds If this is true, a COL
hsion is likely once every two million
years. Such a smash probably would
devaState an area the size of Texas.
1t has happened before, but probably
not in the time of man.
A far more remote possibility is that
of the collision of the sun with another
star.
There are several hundred billion
stars in the Milky Way galaxy. The
suns closest neighbor is at a distance
of about five light years-the distance
covered by light in five years at speed
of 10000 miles a second. This prob
ably is an average stellar distance.
Probably, in the galaxy as a whole,
there have been one or two such en-
counters in the last three billion years.
The likelihood that the sun will be the
victim Of the next one is very slight
indeed.
The disintegration of the moon. how
ever, seems bound to happen, DR.. Will
son says.
The rate of the earths rotation, as
shown in the length of the day, grad
ually is getting slower through the fric-
ton OF tides on the bottoms of shallow
seas. Eventually the length Of the
planets day and the month will be-
come equal.
After this happens, the moon will
be drawn closer and closer to the earth.
When it gets within about 10000 miles
it will be torn apart by gravitational
attraction. Much of the debris will rain
on the earth.
This catastrophe, DR.. Wilson says,
can be expected about Jan. /, 100, ,00O,-
100000 A. D.
New Varnish for Artists.
An apparently ideal varniSh for
paintings has been produced for the
National Gallery of Art by Mellon Insti-
tute chemists.
In the conservation of great pictures
it is necessary that they be sent to the
laboratory periodically for repair of
cracks, blisters, brittle canvas, and
other reasons. For this reason, picture
varnish must readily be removable
Hitherto artists had to choose from
materials available in nature. Resins
for varniShes were selected from the
few that would dissolve readily in
oOlNCA1Io OAAdO WOu1u IlOb dI1SCI GIl6 pic
ture itself.
The ones most easily available were
damar, resin from the Avian gurjun
tree, and mastic, from the pistachio
tree. These are widely used today al
though they become badly discolored
after few decades.
Within recent years a large number
OF synthetic resins have appeared on
the market. None, however, have been
particularly well adapted for the artists
use. The Mellon Institute chemists
spent more than year on the research
problem.
The two together, the Mellon chem
lists predict. will make the very finest
possible picture varnish.
1t is now being given a thorough test
at the National Gallery of Art which
houses some of the worlds most VAL
liable paintings If the tests uphold
predictions, the formula for the varnish
will be published.