Some of the constellations seen when looking north in March from six to nine o'clock.
And now, leaving Castor and going round to the east, we pass through the constellation Leo or the Lion, and I want you particularly to notice six stars in the shape of a sickle, which form the front part of the lion, the brightest, called Regulus, being the end of the handle.[3] This sickle is very interesting, because it marks the part of the heavens from which the brilliant shower of November meteors radiates once in thirty-three years. This is, however, too long a story to be told to-night, so we will pass through Leo, and turning northwards, look high up in the north-east (Fig. 58), where "Charles's Wain" stretches far across the sky. I need not point this out to you, for every country lad knows and delights in it. You could not have seen it in the twilight when Sirius first shone out, for these stars are not so powerful as he is. But they come out very soon after him, and when once fairly bright, the four stars which form the waggon, wider at the top than at the bottom, can never be mistaken, and the three stars in front, the last bending below the others, are just in the right position for the horses. For this reason I prefer the country people's name of Charles's Wain or Waggon to that of the "Plough," which astronomers generally give to these seven stars. They really form part of an enormous constellation called the "Great Bear" (Fig. 59), but, as in the case of Orion, it is very difficult to make out the whole of Bruin in the sky.
Fig. 59.
The Great Bear, showing the position of Charles's Wain, and also the small binary star ξ in the hind foot, whose period has been determined.
Now, although most people know Charles's Wain when they see it, we may still learn a good deal about it. Look carefully at the second star from the waggon and you will see another star close to it, called by country people "Jack by the second horse," and by astronomers "Alcor." Even in your small telescopes you can see that Jack or Alcor is not so close as he appears to the naked eye, but a long way off from the horse, while in my telescope you will find this second horse (called Mizar) split up into two stars, one a brilliant white and the other a pale emerald green. We do not know whether these two form a binary, for they have not yet been observed to move round each other.
Take care in looking that you do not confuse the stars one with another, for you must remember that your telescope makes objects appear upside down, and Alcor will therefore appear in it below the two stars forming the horse.
But though we do not know whether Mizar is binary, there is a little star a long way below the waggon, in the left hind paw of the Great Bear (ξ, Figs. 58 and 59), which has taught us a great deal, for it is composed of two stars, one white and the other grey, which move right round each other once in sixty years, so that astronomers have observed more than one revolution since powerful telescopes were invented. You will have to look in my telescope to see the two stars divided, but you can make an interesting observation for yourselves by comparing the light of this binary star with the light of Castor, for Castor is such an immense distance from us that his light takes more than a hundred years to reach us, while the light of this smaller star comes in sixty-one years, yet see how incomparably brighter Castor is of the two. This proves that brilliant stars are not always the nearest, but that a near star may be small and faint and a far-off one large and bright.
Fig. 60.
