Learn more physics!
Is the reason why space appears to be dark from the fact that space is a vaccum and for us to see any light, light has to first bounce off an object say a planet for instance?
- chris (age 10)
saint marys, Halifax, Canada
You guessed it. There are only 2 ways to get light. One is if something (like a star) produces the light itself. The other is if the light bounces off of something (like a planet). And since the vast majority of space is empty (a vacuum), there’s just nothing there to see.
(republished on 07/29/06)
Follow-Up #1: space and light
I heard somewhere that space isn't actually a vacuum, that it is made up of dark matter. If so, then why doesn't the light bounce off of that and illuminate space?
- Savannah (age 13)
We don't really know yet what space is made up of. It's not dark matter, however, which is just some more stuff hanging out in space, like us. The dark matter is different from us, however, in that it doesn't interact with light, so you can't see it.
You may be thinking of dark energy, which may have some connection with whatever makes up space. Whatever our space is, however, it provides the right sort of thing for light to travel in freely. Think of a wave on a string. The string doesn't get in the way of the wave, it provides the base for the wave to exist.
(published on 10/01/09)
Follow-up on this answer.