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Black Holes, Quasars, Super Novas, White Dwarfs – no, it’s not the latest plot synopsis for Babylon Five. These are all astronomical terms. They are terms that most of us tend to nod knowingly to. In reality, however, most of us haven’t got a clue what they really are. Time for a crash course in astronomical terminology? You bet.

Now, the universe is a pretty big subject. Our own galaxy, the Milky Way, is some 600 quadrillion miles across. The entire universe may contain up to 100 billion other galaxies. It’s not surprising, then, astronomers don’t know everything about the vast open spaces beyond planet earth. Virtually every new discovery, in fact, serves to raise a question mark over what was previously believed. Yet, what is known still comprises a substantial body of knowledge. Let's tap into some of it.

GALAXY: This is a large group of stars rotating around a central nucleus. Ours - called the Milky Way – is part of a 20 fold cluster which clings together much like a bunch of grapes.

The following terms are all related to the life cycle of a star.

RED GIANT: After a star has burned out its hydrogen supplies (which could take billions of years) the core contracts. The outer layer of the star then expands and becomes cooler. This process gives off a reddish glow. This is what is called a Red Giant.


SUPERNOVA: This is the explosion that ends the life of a star. From earth it is seen as a diamond illuminating in the night sky.

PULSAR: The remains of a supernova. The once huge star has now become a fast spinning globe of approximately 20 miles in diameter. From our vantage point it looks like a pulsing light.

BLACK HOLE: Current understanding is that a black hole is simply the result of a really big star exploding (supernova). Such an explosion would cause the force of gravity to continue beyond the pulsar stage. So, the star would actually disappear, leaving behind only its gravity and a black hole where it used to be. This black hole would act as a supercharged cosmic whirlpool – ready to devour whatever came too close.

Have scientists really discovered these black holes? Possibly. They have definitely discovered some very strange objects that can at present most easily be explained as black holes. But, like the universe itself, scientific knowledge is fluid and never ending. Who knows what new data will throw out today’s accepted knowledge. And then, we’ll have to start learning all over again!