Exploding stars!
Nearly a thousand years ago, in the year 1054, a new star suddenly
appeared in the sky. It was tremendously bright—so bright it could be
seen even in daytime. For two years, the strange new star glowed in the
sky, day and night. Then, it slowly began to fade away. And, after a
time, it disappeared.
Where had this bright new star come from? And what became of it?
Actually, it wasn’t a new star at all. It was a star that had exploded.
Certain kinds of stars sometimes do explode. A kind of small star called
a white dwarf star may suddenly flare up and become much, much brighter.
Such an explosion is called a nova, which means “new,” because it
looks like a bright new star appearing in the sky. But after a time the
brightness fades away. The star becomes no brighter than it was before
it exploded.
When a very large star called a supergiant begins to die, it, too,
explodes. But this is a tremendous explosion that destroys the star.
The explosion sends a gigantic cloud of glowing gas rushing out into
space, and the once-giant star suddenly becomes a little white dwarf
star. This kind of explosion is called a supernova. A star that becomes
a supernova may become a billion times brighter. It was the light of a
supernova that was seen in the sky in 1054.
