Orion affords the observer a splendid field of research.  It is a constellation rich in double and multiple stars, clusters, and nebulae.  We will begin with an easy object.

The star [delta] (Plate 3), or Mintaka, the uppermost of the three stars forming the belt, is a wide double.  The primary is of the second magnitude, the secondary of the seventh, both being white.

The star [alpha] (Betelgeuse) is an interesting object, on account of its colour and brilliance, and as one of the most remarkable variables in the heavens.  It was first observed to be variable by Sir John Herschel in 1836.  At this period its variations were “most marked and striking.”  This continued until 1840, when the changes became “much less conspicuous.  In January, 1849, they had recommenced, and on December 5th, 1852, Mr. Fletcher observed [alpha] Orionis brighter than Capella, and actually the largest star in the northern hemisphere.”  That a star so conspicuous, and presumably so large, should present such remarkable variations, is a circumstance which adds an additional interest to the results which have rewarded the spectrum-analysis of this star by Mr. Huggins and Professor Miller.  It appears that there is decisive evidence of the presence in this luminary of many elements known to exist in our own sun; amongst others are found sodium, magnesium, calcium, iron, and bismuth.  Hydrogen appears to be absent, or, more correctly, there are no lines in the star’s spectrum corresponding to those of hydrogen in the solar spectrum.  Secchi considers that there is evidence of an actual change in the spectrum of the star, an opinion in which Mr. Huggins does not coincide.  In the telescope Betelgeuse appears as “a rich and brilliant gem,” says Lassell, “a rich topaz, in hue and brilliancy differing from any that I have seen.”

Turn next to [beta] (Rigel), the brightest star below the belt.  This is a very noted double, and will severely test our observer’s telescope, if small.  The components are well separated (see Plate 3), compared with many easier doubles; the secondary is also of the seventh magnitude, so that neither as respects closeness nor smallness of the secondary, is Rigel a difficult object.  It is the combination of the two features which makes it a test-object.  Kitchener says a 1-3/4-inch object-glass should show Rigel double; in earlier editions of his work he gave 2-3/4-inches as the necessary aperture.  Smyth mentions Rigel as a test for a 4-inch aperture, with powers of from 80 to 120.  A 3-inch aperture, however, will certainly show the companion.  Rigel is an orange star, the companion blue.

Turn next to [lambda] the northernmost of the set of three stars in the head of Orion.  This is a triple star, though an aperture of 3 inches will show it only as a double.  The components are 5” apart, the colours pale white and violet.  With the full powers of a 3-1/2-inch glass a faint companion may be seen above [lambda].