Lazy, or perhaps my google-fu isn’t too hot. In any case, I forgot to ask the lady giving a little talk in the Armagh Planetarium during the week about nebulae.
When we see a nice picture in the papers or the news etc of a nebula, are they really the pleasant colours we see, a red or blue usually, but sometimes other pale colours. Like this picture of the Trifid nebula. When it’s declared to be a true colour, this means it’s literally the colour we would see if we were passing by in a spaceship?
And if we were inside a nebula, what would we notice? Would the “sky” around us appear like a dimmer version of the night sky on a clear night on earth? Does it depend on the type of nebula, or is the dust and gas just too diffuse to make any difference from inside?
They are very faint. Many of them are big enough to be a bold and beautiful sight in the sky, but they aren’t because they are faint.
Since eyes respond in a somewhat nonlinear way to light, it is debatable what it should mean to say that an astrophotograph shows natural color, but I think many accept a version that assumes eyes are linear, and shows an energy mixture that is the same as the true energy mixture.
Passing by in a spaceship wouldn’t much change this. Perhaps the rest of the sky could be darker, or perhaps you’d be long used to staring at blackness before you happened upon a nebula. It would still look very faint, though.
We ARE in a nebula, though not a gas nebula. When my grandfather was learning about the night sky, galaxies and gas nebulae and planetaries were all called nebulae, and though it was obvious that there were differences between their appearances, they weren’t sure what if anything it meant. In that context, we are inside the Milky Way, which must look alot like the Andromeda nebula.
Gas nebulae, by the way, can have pretty spectrally pure colors, for the same reason that some “neon” signs do. If something made them emit much more light but of the same nature, we would see startling little patches of color in the sky with our eyes.