her coming again out of the
eighteenth century would fail to understand the thought and speech of
even the common man.

In no other particular has the change been more marked than with
respect to the general theory of the planetary and stellar worlds. A
New Astronomy has come and taken the place of the old. The very
rudiments of the science have to be learned as it were in a new
language, and under the laws and theories of a new philosophy. Nature
is considered from other points of view, and the general course of
nature is conceived in a manner wholly different from the beliefs of
the past.

In a preceding study we have explained the general notion of planetary
formation according to the views of the last century. The New
Astronomy presents another theory. Beginning with virtually the same
notion of the original condition of our world and sun cluster, the new
view departs widely as to the processes by which the planets were
formed, and extends much further with respect to the first condition
and ultimate destiny of our earth. The New Astronomy, like the old,
begins with a nebular hypothesis. It imagines the matter now composing
the solar group to have been originally dispersed through the space
occupied by our system, and to have been in a state of attenuation
under the influence of high heat. Out of this condition of diffusion
the solar system has been evolved. The idea is a creation by the
process of evolution; it is evolution applied to the planets. More
particularly, the hypothesis is that the worlds of our planetary
system grew into their present state through a series of stages and
slow developments extending over aeons of time.

This is the notion of world-growth substituted for that of
world-production en masse by the action of centrifugal force and
discharge from the solar equator. The New Astronomy proposes in this
respect two points of remarkable difference from the view formerly
entertained. The first relates to the fixing of the planetary orbits,
and the other to the process by which the planets have reached their
present mass and character. The old theory would place a given world
in its pathway around the sun by a spiral flinging off from the
central body, and would allow that the aggregate mass of the globe so
produced was fixed once for all at the beginning. The new theory
supposes that a given planetary orbit, as for instance that of the
earth, was marked in the nebula of our system before the syst