Evening star., 1899-04-01

that the surfaces of the two bodies are
equally brilliant-that they emit the same
amount of light square mile for square mile
then 1t follows that Sirius, having fifty
times as great a surface as the sun, has
diameter very nearly seven times as
great. The assumption is, however un-
doubtedly not true. so that the conclusion
drawn from it is at best a wild guess.
Size of Sirius.
The discovery of the companion of Sirius
by Clark in 1862 enabled astronomers to
determine the mass of Sirius. and 1t was
found that while Il is fifty times as bright
as the sun, it contains only about twice as
much matter as the SUMS twice as heavy
Professor See now tells us that since Sirius
mas reached the blue-white stage of heat
1t must be more dense. more compact than
the sun, which has reached only the yellow
stage. The probability is. therefore, that
though Sirius is twice heavy as the SUM-
1t does not surpass the sun greatly if at
ALL in bulk. Indeed, strict application of
the law" would make 1t considerably
smaller than the sun. And So if there is
no mistake about this law. We lose at least
one OF the giant suns which we have be-
come accustomed to imagine in space
SIRIUS is more brilliant than the sun not
because 1t is a larger body but because it
Is hotter body, just an electric arc
light is more brilliant than a gas Jet
though the incandescent carbon points are
smaller than the gas flame.
The Planets.
Mercury will be an evening star until the
18th, and after that date a morning star.
but too close to the sun to be visible.
Venus is a brilliant morning star. about
two and half hours in advance of the sun.
and visible in the southeast
Mars is an evening star, about four de-
grees south of Pollux, the more southerly
or the Twins. 1t now shines as an ayera ge
star of the first magnitude. Some interest
ing drawings of this planet, made by Mr.
A. \. Douglass, at the Lowell observatory,
FIagstan, Ariz., last January, are given in
the March number of Popular Astronomy
The planets northern hemisphere was that
most favorably situated for observing and
some new details OF the markings of this
hemisphere were secured. The canals
are as abundant here apparentlv as in
the southern hemisphere which has hither
TO been examined the most thoroughly
OWING to the planets great distance from
US, when in opposition this year and tn the
unfavora bleness of the winter season for
observing, no new light has been gained
either as to the nature of the planet's
surface markings or of its condition as re-
CARDS habitability.
Evening Stars.
Jupiter is now a splendid evening star, in
Libra, rising at about pm. Jupiter will
be In opposition to the sum- crossing the
ihefiuidn at m1dnight on the 18th of the
month.
Saturn has become an evening star, rising
JUST before midnight. The discovery of a
ninth satellite of Saturn by means of pho-
tography has recently been announced from
the Harvard College observatory The dis
covery was made from the comparison of
plates taken Tor the purpose of making
search for such a body at Areuuipa. perm
In August last. The new satellite appears
as a star of less than the fifteenth magni-
tuoe, ana Is therefore beyond the reach of
any but the largest telescopes Prof Pick
erfng estimates its diameter to be about
2oo miles. 1t is worthy of note that the
eighth satellite Gin order of discovery. Hy-
RP, PeI,oh, aiso was discovered at the Harvard
College observatory by Bond in 1s4S
Uranus. in the Scorpion, rises about an
hour before Saturn. Neptune, appearing as
q star of the tenth magnitude, is still plod-
aing mis- slow way through the constellation
Taurus, and is now near the tin of the
Bulls southern horn.