sun among the stars.

[Illustration: Fig. 85.--Orion, Sirius, and the Neighbouring Stars.]

The Pleiades are shown in the figure (Fig. 84), where a group of ten
stars is represented, this being about the number visible with the
unaided eye to those who are gifted with very acute vision. The lowest
telescopic power will increase the number of stars to thirty or forty
(Galileo saw more than forty with his first telescope), while with
telescopes of greater power the number is largely increased; indeed, no
fewer than 625 have been counted with the aid of a powerful telescope.
The group is, however, rather too widely scattered to make an effective
telescopic object, except with a large field and low power. Viewed
through an opera-glass it forms a very pleasing spectacle.

[Illustration: Fig. 86.--Castor and Pollux.]

If we draw a ray from the Pole Star to Capella, and produce it
sufficiently far, as shown in Fig. 85, we come to the great
constellation of our winter sky, the splendid group of Orion. The
brilliancy of the stars in Orion, the conspicuous belt, and the
telescopic objects which it contains, alike render this group
remarkable, and place it perhaps at the head of the constellations. The
leading star in Orion is known either as a Orionis, or as
Betelgeuze, by which name it is here designated. It lies above the three
stars, d, e, z, which form the belt. Betelgeuze is a
star of the first magnitude, and so also is Rigel, on the opposite side
of the belt. Orion thus enjoys the distinction of containing two stars
of the first magnitude in its group, while the five other stars shown in
Fig. 85 are of the second magnitude.

The neighbourhood of Orion contains some important stars. If we carry on
the line of the belt upwards to the right, we are conducted to another
star of the first magnitude, Aldebaran, which strongly resembles
Betelgeuze in its ruddy colour. Aldebaran is the brightest star in the
constellation of Taurus. It is this constellation which contains the
Pleiades already referred to, and another more scattered group known as
the Hyades, which can be discovered near Aldebaran.

[Illustration: Fig. 87.--The Great Bear and the Lion.]

The line of the belt of Orion continued downwards to the left conducts
the eye to the gem of the sky, the splendid Sirius, which is the most
brilliant star in the heavens. It has, indeed, been necessary to create
a special order of magnitude for the reception of Sirius alone;