st magnitude, and perhaps out-blaze Sirius or Capella in our
winter sky.

None of the causes for these changes we have been able to conjecture
seem very satisfactory. The stars may have opaque planets revolving
about them, shutting off their light; they may rotate, and have
unequally illuminated sides; they may revolve in very elliptical
orbits, so as to greatly alter their distance from us; they may
be so situated in regard to zones of meteorites as [Page 223] to
call down periodically vast showers; but none or all of these
suppositions apply to all cases, if they do to any.

_Temporary, New, and Lost Stars._

Besides regular movements to right and left, up and down, to and
from us--changes in the intensity of illumination by changes of
distance--besides variations occurring at regular and ascertainable
intervals, there are stars called _temporary_, shining awhile and
then disappearing; _new_, coming to a definite brightness, and so
remaining; and _lost_, those whose first appearance was not observed,
but which have utterly disappeared.

In November, 1572, a new star blazed out in Cassiopeia. Its place
is shown in Fig. 67, ch g being the stars

d *
g ch

in the seat of the chair, and d being the first one in the back.
This star was visible at noonday, and was brighter than any other
star in the heavens. In January, 1573, it was less bright than
Jupiter; in April it was below the second magnitude, and the last
of May it utterly disappeared. It was as variable in color as in
brilliancy. During its first two months, the period of greatest
brightness, it was dazzling white, then became yellow, and finally
as red as Mars or Aldebaran, and so expired.

A bright star was seen very near to the place of the _Pilgrim_,
as the star of 1572 was called, in A.D. 945 and 1264. A star of
the tenth magnitude is now seen brightening slowly almost exactly
in the same place. It is possible that this is a variable star
of a period of about three hundred and ten years, and will blaze
out again about 1885.

But we have had, within a few years, fine opportunities [Page 224]
to study, with improved instruments, two new stars; On the evening
of May 12th, 1866, a star of the second magnitude was observed in
the Northern Crown, where no star above the fifth magnitude had been
twenty-four hours before. In Argelander's chart a star of the tenth
magnitude occupies the place. May 13th it had declined to the third
magnitude, May 1