haze, which
proved to be the great nebula. Ever since his time this object has been
diligently studied by many astronomers, so that very many observations
have been made of the great nebula, and even whole volumes have been
written which treat of nothing else. Any ordinary telescope will show
the object to some extent, but the more powerful the telescope the more
are the curious details revealed.

[Illustration: Fig. 98.--The Multiple star (th Orionis) in the
Great Nebula of Orion.]

In the first place, the object which we have denoted by A (th
Orionis, also called the trapezium of Orion) is in itself the most
striking multiple star in the whole heavens. It consists really of six
stars, represented in the next diagram (Fig. 98). These points are so
close together that their commingled rays cannot be distinguished
without a telescope. Four of them are, however, easily seen in quite
small instruments, but the two smaller stars require telescopes of
considerable power. And yet these stars are suns, comparable, it may be,
with our sun in magnitude.

It is not a little remarkable that this unrivalled group of six suns
should be surrounded by the renowned nebula; the nebula or the multiple
star would, either of them alone, be of exceptional interest, and here
we have a combination of the two. It seems impossible to resist drawing
the conclusion that the multiple star really lies in the nebula, and not
merely along the same line of vision. It would, indeed, seem to be at
variance with all probability to suppose that the presentation of these
two exceptional objects in the same field of view was merely accidental.
If the multiple star be really in the nebula, then this object affords
evidence that in one case at all events the distance of a nebula is a
quantity of the same magnitude as the distance of a star. This is
unhappily almost the entire extent of our knowledge of the distances of
the nebulae from the earth.

The great nebula of Orion surrounds the multiple star, and extends out
to a vast distance into the neighbouring space. The dotted circle drawn
around the star marked A in Fig. 97 represents approximately the extent
of the nebula, as seen in a moderately good telescope. The nebula is of
a faint bluish colour, impossible to represent in a drawing. Its
brightness is much greater in some places than in others; the central
parts are, generally speaking, the most brilliant, and the luminosity
gradually fades away as