Why is Space dark?

If you look at the sky late at night when it is dark, you will see a dark sky. You will get a better view in the countryside because in a city, the many bright lights from street lamps and buildings make the darkness, well, less dark.

But why is the sky or outer space, dark? Well we know the Earth gets its light from the Sun and because the Earth spins or rotates there is a time when our planet is not facing the Sun. That’s how we get night and day.

But if the night sky or outer space is filled with millions of stars, and it is, how come the light from all those stars doesn’t light up the sky. Why is outer space so dark?

Well there really isn’t a simple answer to that question. But there are several things we can think about. First of all is the matter of reflection. If you are in a dark room and you light a candle, you will get some light. But why? Well because the flame has some surface from which it can reflect light – the light can bounce off a wall or a piece of furniture and even the ceiling.

Now in space there are no walls and there is no ceiling. At least we don’t think so. If there is light in space it needs a surface to bounce off to send that light to other places in space. That’s one reason why space is dark.

And here’s another important point. Where is the end of space? Your house has a boundary probably marked with a fence. A basketball court, tennis court, swimming pool and lawn all have a boundary. We know where they end. But where is the end of outer space?

The word infinite is important. It means endless. Now that can be hard to understand because everything we know about and everyone we know has an end. Every animal, insect, flower and person dies; they have an end. But outer space does not have an end, it is infinite. In fact there are some scientists who believe that space is still growing. It’s getting bigger.

Of course we can never be certain about some things and if space is as big as many scientists believe it is, then how can they know? I mean no human has ever traveled to the ‘end’ of space and come back to talk about it. Our telescopes cannot see forever. On Earth because our planet is curved, we can only see as far as the horizon.

So the answer to why space is black may very well be because space has no end and it has no walls.

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