Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1877-08-29
MARS.
The Discovery of its Satellites.

Inc DtSCOFtiy vi ~ ,SHte'ii'H'
A Washington special to the Chicago
Tribune of August 10, says: The great
telescope in the hands of Prof. Hall has
lust ~signalized itself by one of the most
surprising discoveries in modern astron-
omy-nothing less, in fact, than one,
and probably two, satellites to the planet
Mars. About II o'clock on Thursday
night Prof. Hall noticed IL very small
star following Mars a few seconds, and
made IN estimate Of its distance from
the planet. Two hours later he looked
again, and was surprised to find that the
star seemed to be following the planet,
a. the distance was not increased, while
the planet was moving away at the rate
Of fifteen seconds an hour. He there
fore made q careful series Of measure
ments, showing that the satellite vas
eighty seconds from the, planet. An
hour later it wa still there, but he made
no further observations, hardly credlting
the great discovery he had made. Next
morning he showed his observations to
Prof. Newcomb, who was 50 confident
that the object must be a satellite that
he calculated roughly the time Of revo-
luton, which he fixed at II day eight
hours, or a little less. This showed that.
the object would pass behind the planet
some time in the following night, and
that, if not seen in the early evening, it
would reappear before daylight in the
morning. In the evening 1t was mvlsl-
bic, but rcappeared, true to the predic-
ton, about t O'Clock in the morning,
with q companion satellite. Prof. Hall
had now so little doubt Of the reality of
the object that he made the discovery
known to Admiral Rogers, the Superin-
tendcnt. 1t was still thought best to
wait for another look before formally
announcing the discovery, especially rs
Prof. NewcOmb's observation showed
that it would be on the opposite side of
the planet on Saturday evening. Hard
Iy was the telescope opened when the
satellite was seen, and It's position de-
termined by several Of the astronomers.
In the course of thc evening an object
which might be another satellite, much
closer To the planet. was found by Mr..
Todd, but nothing could be determined
respecting the time of revolution. The
observations of the other one showed it's
time of revolution TO be about thirty
hours, but several weeks observation
will be required to settle this exactly.
Scientific authorities here regard 1t rs
ranking among the greatest telescope
discoveries of the ,ccntury,-the only
two which exceed it being that Of the
asteroid group in 1901, and of the plan
ct Neptune in 1916. Prof. Hall, the for
,..a... 1.-..,,. &c H., .,t.lhtA Ia. Z
been attached to the Observatory since
1862. When Prof. Ncwcomb resigned
the charge of the great telescope in 1870
he succeeded to it. He is an able and
learned mathematician. and a most CON
observer. Prof. Ncwcomb
tclegraphed this discovery this morning
to the European ob~Scrvatorles, and 1t Is
hoped that the weather there will permit
of further observations. Prof, Hail, who
has kept continuous watch ut the instru-
mcnt for a week, and who was fortunate
enough to make this remarkable discov-
cry, makes the following statement to Il
representative of the It3bune who called
upon him: "Thc first satellite of Mars
was discovered ut the Naval Observatory
in Washington on the night OF Aug. Is.
1t was first seer ut II hours and II min
utcs. 1t has been observed on the
nights of the 10th, 18th, and 18th of
August. The time of the revolution of
this satellite about Mars il about thirty
hours. It's greatest apparent distance
from the centre of Mars is SO seconds of
arc. | think | saw another satellite Sat
urday morning about 4 o'clock, but Of
the existence of the second satellite |
am not absolutely certain. | believe,
however, that there are two, and expect
to be able to determine this tonight.
commence observations again about
midnight, The satellite, III It's appear
ancc, is a faint object Of about the thir-
tccnth or fourteenth magnitude, and 1t
was possible to discover it only by put
ting Mars, which is exceedingly bright,
out of the field of the telescope, rs to
yet rid of the brilliant light of that plan
ct The distance of the first satellite
Is between 1900 or $1,000 miles, which
is less than that of any known planet.
The inEcr one, ~ To the existence of
which the astronomers are not yet abso-
lutcly certain, Is still closer. The diam
ctcr is very small, probably not q
than 800 miles.