New-York tribune., 1877-08-20
a SATELLITE TO MARS.

BRILLIANT ASTRONOMICAL DISCOVERY.
PROF. HALL OF THE NAVAL oBst tRyATOgY. WASH
ISGToN, DISCOVERS TgLLITE To MARs-How
AND WHEN THE DISCOVERY WAS MADE.
lBr TELEGRAPH TO THE TRBUSEl
WASHINGTON Aug 19.-The great Telescope OF tho
Naval Observatory has just signazed Itself. in tho
hands OF Prof. Hall, b. one of the most remarkable
additions to modern astronomy-nothlag less, in
fact than the discovery of satellite and probably
two to the planet Mars. About IL o'clock Oh Ihurs-
day night Prof Hall noticed very small follow
ing Mars few seconds and mado an estimate of its
distance from the planet Two hours later he looked
again, and was surprised 10 find that the star
seemed to be still following the planet. As the dis
tance had not increased while the planet was NOV
ing away at the rate Of fifteen seconds an hour, he
therefore made a careful series Of measures, which
showed that the satellite was eighty seconds from
the planet. An hour later II still therc, but Mr.
Hall made further observation, hardly crcditIng
the great discovery he had made.
On Friday morning he showed his observations
to Prof. Newcomb, who confident that the
object must be satellite that he calculated rough
ly the time of its revolution, which he fixed at ono
day eight hours or a little less This showed that tho
object would pass behind the planet some time dar-
ing the following night and that If not in ealy
evening it would reappoar before daylight ia tho
morning. la the evening it was invisible, bat re-
appeared, 10 the prediction, about l O'Clock in
the morning with a companion satellite. PrOL llAu
had now little doubt of the reality Of the ojcct
that he made the discovery known to AIIni-
raj Rogers, tho Superintendent. It stii
thought best to wait for another .cok be-
fore formally announcing The discovery, espe-
cally as Prof. Ncwcombs calculation showed
that il would be the opposite side Of the planet
OH Saturday evening. Hardly was The telescope
turned on Mars when the satellite was seen aud its
position determined by several Of the astronomers
In the course Of the evening an object. which might
be another satellite much closer 10 ths planet, was
found by Mr.. Todd but nothing could b9 deter
mined respecting the time Of its revolution. Ths
observations Of the first satellite showed 10 time Of
revolution % be about thirty hours, but several
weeks observation viii be required 10 setie this
actly.
Scientific authorities here regard this as ranking
among the greatest telescope discoveries Of tho
century; the only two which exceed il being that of
the asterold group in 1901, and Of the planet Nep-
tune in 1916. Prof Hall, the fortunate dlscoyerer
of the satellite has been attached TO the observatory
since 1862. When Prot. Newcomb resigned tho
charge Of the great telescope, in 1873, he sue
ceeded to it. He is able and learned
mathematician, and en- unostentatious and con-
scientious observer. Prof. Newcomb telegraphed
the discovery Of the satellite this morning TO
the European obseryatOres and il is hoped that tho
weather there will permit Of further observation.
Prof. Hall. who has kept continuous watch at ths
instrument for week. and who was fortunate
enough to make this remarkable discovery. furnishes
the following statement TO representative of Tue
TRIBUNE
Tho first satellite OF Mars discovered 40
the Naval Observatory, In Washington, on the
nlght Of August l6 1t was first seen at forty
two minutes past eleven 1t has been observed on
the nights of the 1Gth I7.h and 18th Of August The
time VI the revolution OF this satellite about Mars Is
about thirty hours Its greatest apparent distance
from the centre Of Mars is eighty seconds Of
arc I think 1 another satellite on Saturday
morning about o'clock, but or the existence
OF this second satellite am not absolutely certain.
believe, however, that there are Two and expect 10 be
able to determine this tonight. as commence obserys
tons again about midnight Tho satellite in It's appear
once is faint object Of about The Of star OF tho
thirteenth or fourteenth magnitude. and 1t possible
to discover il only by putting Mars which Is exceed
iugly bright out Of the field Of the telescope, so
as TO get rid OF the brilliant light Of that planet
The distance Of the first satellite from the planet
is between fourteen and fifteen thousand miles,
which is less than that of any other known satellite
from its primary, and only about oEe-sixteeeth tho
distance of the moon from the earth The inner one
as 10 the existence of which the astronomers are not
yet absolutely certain, is still closer. The diameter
Of the new satellite is very small probably not
than fifty or 100 miles.
OFFICIAL ANNOUNCEMENT or IHE DISCOVERY.
The following dispatch announces officially the
discovery of the new satellites:
WASHINGTON, Aug 19.-Two satellites OF Mars have
been discovered by Han at Washingtou. Fst sIongs
ton West August 1s. eleven hours, asdngton time
Distance eighty sesonds thirty hours. Distance
OF second, fifty seconds. JOsETu HENRY.