[bloodhound31]

A question for those in the know.

I have been reading up on the speed of light to enable me to answer better, the queries I get from the general population.

I am thinking about different wavelengths (Infra-red to Ultraviolet) and our employment of narrow-band filters for astrophotography.

As far as I can make out, light leaves object x, travels through the vacuum at around 300000kmps (all wavelengths the same speed).

When it passes through things like our atmosphere (transparent matter) this has the effect of slowing down the different wavelengths very slightly, breaking them up into the spectrum.

Is this a correct assumption?

How are the colours of the spectrum different from something like, hydrogen-alpha, or oxygen III (filters). Are they just different levels of the same spectrum?

Please keep answers simple for us with no uni degree or mathematical ability.

Baz.