On the other hand, we find (in the Pleiades) wisps and
streamers of nebulous matter clinging about great clusters of
stars, suggesting that they are material left over when these
clustered worlds crystallised out of some vast nebula; and
enormous stretches of nebulous material covering regions (as in
Perseus) where the stars are as thick as grains of silver. More
important still, we find a type of cosmic body which seems
intermediate between the star and the nebula. It is a more or
less imperfectly condensed star, surrounded by nebular masses.
But one of the most instructive links of all is that at times a
nebula is formed from a star, and a recent case of this character
may be briefly described.
In February, 1901, a new star appeared in the constellation
Perseus. Knowing what a star is, the reader will have some dim
conception of the portentous blaze that lit up that remote region
of space (at least 600 billion miles away) when he learns that
the light of this star increased 4000-fold in twenty-eight hours.
It reached a brilliance 8000 times greater than that of the sun.
Telescopes and spectroscopes were turned on it from all parts of
the earth, and the spectroscope showed that masses of glowing
hydrogen were rushing out from it at a rate of nearly a thousand
miles a second.
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