The Seattle post-intelligencer. [volume] (Seattle, Wash. Terr. [Wash.]) 1888-1914, 1900-02-25
THEY ARE LOOKING
FOR ANOTHER PLANET.
Astronomers Seek the
Intra.MercuriaI
Wanderer.
During the Coming Eclipse. Prof. Picker.
ing Will Try to Verify One OF
Leverrier's Predictions.

~HE announcement that Prof. Will
~ liam H. Pickering, of the Harvard
II observatory staff, will make pho
tofraphic search for an intra-Mer-
- curial planet during the coming
eclipse of the sun revives an interesting
subject OF speculation and controversy. So
far as the astronomers know, only two
planets, Venus and Mercury. have orbits
that lie within that of the earth. Mer-
curry IL the nearest to the sun, its average
distance from that body being Ss,WoWD
miles But in 1859 I,everrier expressed the
belief that still another planet existed,
whose path was inside that OF Mercury.
He was led to this conclusion by mathe-
NAUTICAL processes. and advanced the the
CRY to account for certain peculiarities OF
Mercury's behavior. When 1t Is remem-
bered that Neptune was discovered In very
much the same manner. 1t Is easy TO
understand the impression which Lever
rier's utteranceS, coming thirteen years
later. made upon the scientific world.
But while the prediction regarding the ex-
istence of a body outside the orbit OF
Uranus was promptly verified, that con-
corning a possible intra- Mercur.ai planet
has not been although more than one
sensation has been produced by sup
posed discovery of this nature.
Scarcely had Leverrier declared his be-
lief that some other body was disturbing
the course of Mercury before compatriot
DR.. Lescarbault, announced that he had
actually observed it moving between him
and the sun and appearing as a small
black dot on the solar surface. The pub
lie was then informed that Vulcan. as
this object was called. had a diameter
of 900 miles, moved around the sun in
trine more than nineteen days and was
about 1900 COO miles distant from the CEN
ter of our planetary system.
7
carbault thus startled the world. But dur
ing that interval of time no one else has
Witnessed the same phenomenon. For
more than twenty years almost daily pho
tographs of the sun have been obtained,
and these have been carefully scrutinized.
IL a round body more than 1000 miles in
diameter were to pass in front OF the sun,
the chance that 1t would escape identifica-
ton for so long period Is very small.
Leverriers theory, however. might be
verified in another way. If a planet really
existed inside of Mercury's orbit, but
moved in plane that was tilted slightly,
1t would not often get an opportunity to
pass directly across the solar disk. Yet
under favorable circumstances 1t might be
perceived in the vicinity OF the sun with
a powerful glass. An exceptional chance
is furnished for such an observation when
the moon completely covers the sun; for
II the skies are clear one can then see
right up to the very limb of the sun.
Hence nearly every total eclipse OF the
sun for forty years has been improved for
this purpose. simon Newcomb made a
search In 1869; william II. Pickering, who
is now about to renew the chase, sought
Vulcan in 1850 with a Photographic tele-
scope, and dozens OF other well-known ex-
perts have made the same attempt.
In 1873 Watson of Ann Arbor, and Swift,
Of Rochester, imagined that they had dis
covered a planet inside OF Mercury's path.