esting point to
remember, and that is that in the Northern Hemisphere, whether it is
winter or summer, the sun is south at mid-day, so that you can always
find the north then, for your shadow will point northwards.

[Illustration: THE ENGLISH SUMMER (LEFT) AND WINTER (RIGHT).]

New Zealand and Australia and other countries placed in the Southern
Hemisphere, as we are in the Northern, have their summer while we have
winter, and winter while we have summer, and their summer is warmer than
ours, because it comes when the earth in its journey is three million
miles nearer to the sun than in our summer.

All this seems to refer to the earth alone, and this chapter should be
about the planets; but, after all, what applies to one planet applies to
another in some degree, and we can turn to the others with much more
interest now to see if their axes are bowed toward the sun as ours is.
It is believed that in the case of Mercury, in regard to its path round
the sun, the axis is straight up and down; if it is the changes of the
seasons must depend on the nearness of Mercury to the sun and nothing
else, and as he is a great deal nearer at one time than another, this
might make a very considerable difference. Some of the planets are like
the earth in regard to the position of their axes, but the two outermost
ones, Uranus and Neptune, are very peculiar, for one pole is turned
right toward the sun and the other right away from it, so that in one
hemisphere there is continuous day all the summer, in the other there is
continuous night, and then the process is reversed. But these little
peculiarities we shall have to note more particularly in the account of
the planets separately.

There is a curious fact in regard to the distances of the planets from
the sun. Each one, after the first, is, very roughly, about double the
distance from the sun of the one inside it. This holds good for all the
first four, then there is a great gap where we might expect to find
another planet, after which follow the four large planets. Now, this gap
puzzled astronomers greatly; for though there seemed to be no reason why
the planets should be at regular distances one outside the other, yet
there the fact was, and that the series should be broken by a missing
planet was annoying. So very careful search was made, and a thrill of
excitement went all through the scientific world when it was known that
a tiny planet had been discovered in the right place.