Part 22

We have a Dumb-bell Nebula near the Lyre.

Oh! who could swing that about? Pray tell me some more about these queer creatures, father.

Many in the south are planetary Nebulæ, as they are in the midst of a cluster of stars. They are always of a pale blue colour. Some are double ones. About a dozen Nebulæ are annular, or ring-shaped. Some are double or treble ringed. Others have rings within rings, and star-like eyes in the darkness. A few have a long, parsnip form. There are solid Nebulæ, and hollow ones. One near Castor was found by Rosse to be arched like eyebrows above and below, with a curious, crab-like form in the middle.

I wonder what it would look like should a better telescope reach it!

Wonder, indeed! Some Nebulæ seen by Herschel get quite another shape with Rosse. The six-feet mirror gives another look to that by the three-feet one.

Then I can scarcely believe the present shapes, as a better instrument may resolve the thing into another creature altogether. But is there any other sort beside the globular and annular?

Yes; a good many are spiral, or corkscrew form.

Something like a shaving that a plane fetches off a plank, father.

But some of your celestial shavings have a wild look. Clever men have fancied that the star-dust is rolling up that way by a sort of gravitation into a regular form.

What of the two clouds in the heavens opposite to the Southern Cross, down in the south? They look uncommonly like monster Nebulæ.

And monsters indeed they are. In the larger one of them three hundred Nebulæ and globular clusters of stars have been distinguished, and fifty in the smaller one.

Then there is room enough in the Cloud for a whole universe?

Yes, when we find the larger Magellanic Cloud, or Nubecula Major, as it is called, taking up many times the space occupied by the sun in the sky. The Nubecula Minor, or Little cloud, is about one-fourth the size of the larger.

What do you mean by Nubecula?

A little cloud. They are called the Magellanic clouds because first noticed in the voyages of Magellan the Portuguese, three hundred years ago.

What a space they must take up in reality!

Especially if, as astronomers believe, the clusters of stars and patches of nebulous matter in the two clouds there are as far off from each other as from this earth.

What is known about the Coal-Sacks?

The larger Coal-Sack, or black empty space not far from the two clouds, is of a pear shape, and occupies a space of eight degrees long by five broad. Its darkness is only comparative, as two hundred stars have been noticed therein by a good telescope.

Are the Nebulæ of the Clouds peculiar?

One in the centre is very large, and has an odd dark space in its middle. It is also surrounded by a circle of ten other Nebulæ.

Like bright guards around a king.

Another consists of four starry centres, or nuclei, which are curiously united by a very faint nebulous matter.

Do, father, tell me more of these Nebulæ.

Then I will talk about some singular filaments, or threads of light, seen around the nebulæ, which have much puzzled astronomers. Those filaments about the Nebulæ of Orion and Argo are wonderfully strange.

They are the arms, I suppose, pointing into the dark space near, as much as to say,--‘You know nothing about us, or of what we can see around us, looking so black to you, and so bright to us.’

Not a bad idea, boy. When Sir John Herschel had a look at our southern hemisphere, he observed beyond the Nebulæ a few scattered, faint bits of light in the dark region, too fine for him to turn into Nebulæ by his glass, and looking like some more distant light blushing through the darkness.

They are like telegraphic messages, father.