s for a brief interval of seconds (or it might be a minute) after
the Sun has reappeared. It was long a matter of discussion whether the
Corona belonged to the Sun or the Moon. In the early days of telescopic
astronomy there was something to be said perhaps on both sides, but it
is now a matter of absolute certainty that it belongs to the Sun, and
that the Moon contributes nothing to the spectacle of a total eclipse of
the Sun, except its own solid body, which blocks out the Sun's light,
and its shadow, which passes across the Earth.

Of the general appearance of the Corona some idea may be obtained from
Fig. 1 (see Frontispiece) which so far as it goes needs little or no
verbal description. Stress must however be laid on the word "general"
because every Corona may be said to differ from its immediate
predecessor and successor, although, as we shall see presently, there
is strong reason to believe that there is a periodicity in connection
with Coronas as with so many other things in the world of Astronomy. A
curious point may here be mentioned as apparently well established,
namely, that when long rays are noticed in the Corona they do not seem
to radiate from the Sun's centre as the short rays more or less seem to
do. Though the aggregate brilliancy of the Corona varies somewhat yet it
may be taken to be much about equal on the whole to the Moon at its
full. The Corona is quite unlike the Moon as regards heat for its
radiant heat has been found to be very well marked.

There is another thing connected with the Sun's Corona which needs to be
mentioned at the outset and which also furnishes a reason for treating
it in a somewhat special manner. The usual practice in writing about
science is to deal with it in the first instance descriptively, and then
if any historical information is to be given to exhibit that separately
and subsequently. But our knowledge of the Sun's Corona has developed so
entirely by steps from a small beginning that it is neither easy nor
advantageous to keep the history separate or in the background and I
shall therefore not attempt to do so.

Astronomers are not agreed as to what is the first record of the Corona.
It is commonly associated with a total eclipse which occurred in the 1st
century A.D. and possibly in the year 96 A.D. Some details of the
discussion will be found in a later chapter,[17] and I will make no
further allusion to the matter here. Passing over the eclipses of 968
A.D. and