How can we see through the interstellar medium?

Question

How can we see through the interstellar medium?

Answer 1

I think there's another way of understanding your question. Perhaps you already know that interstellar space is virtually empty. But maybe you think light needs a medium to propagate, like sound. Sound waves don't propagate in a vaccuum, but light waves (and all forms of electromagnetic radiation) do. So that's how we can see through the 'medium' even though the medium is empty.

Answer 2

With radio telescopes. Radio waves emitted from the core of our galaxy, for example, tell us what's there -- how dense the star clusters are near the core, how fast they're moving relative to us or to the core, and so on. The radio waves have no problem penetrating the interstellar medium because of their longer wavelengths. Sort of like sand through a spaghetti strainer. Radiotelescopes can receive and interpret these radio waves (i.e., light waves of a certain frequency). "Telescopes" built to detect x-rays also can map stuff through the interstellar medium, the same way, because x-rays also are able to penetrate all the dust and stuff that's out there.

Answer 3

Because Interstellar Medium is sparse gas and dust located between the stars of a galaxy. It's like why water looks clear when its full of microbes. Losts of stuff in an even greater amount of space.

Answer 4

Using all sorts of methods......from radio, to infra-red, UV, gamma rays, x-rays etc etc.....Any telescope which can use any part of the electromagnetic spectrum can see through the interstellar medium. And when one won't see through parts of it, then another using a different wavelength of EMR is used that can penetrate what they're looking at.

Answer 5

What's the e-folding optical depth of interstellar space? A long ways, I bet.

Answer 6

Because it is extremely thin. For all practical purposes it is a vacuum. Better than any vacuum we can make on Earth. There are a few atoms per cubic meter, but compared to Earth's atmosphere that is almost nothing.

Answer 7

I think the answer should be obvious... there is nothing in space to block our view of it, save stars, planets, galaxies and the like. And that's what we're looking at anyway. Space is not actually "black", it is just "light-absent" when we are not on the Sun side.

Answer 8

X-Ray Specs, from the back of old comic books.

Answer 9

There's nothing there to absorb the light waves.

Answer 10

Because it is transparent, light travels thru it, anywhere light is, we can see.