Do Nebulas actually have visible colour?

[Planetarian]

I'm just starting observing the night sky with a telescope so I'm just a beginner. I've seen images online of nebulas that look great and full of colour. I'm just wondering if we would actually see them colourful if we looked into our telescope, or people colour them in on purpose. If they do, then what's the point of doing so? 

Edited September 27, 2020 by Planetarian

[Kyle Allen]

Most nebulae are too faint to see in colour with our eyes. There are a few exceptions though. I’ve seen a green tint to the Orion Nebula through my eight inch Dobsonian. Also, many planetary nebulae have a visibly bluish-green colour due to their high surface brightness. 
 

Long exposure photography reveals detail and colour that can’t be seen visually. Our eyes see in real-time but with practice and patience you can develop your observing skills to see more detail in deep sky objects. Try looking slightly off to the side of the object you are trying to observe and it will appear to suddenly brighten (or become visible if it is that faint) because the light falls onto your rod cells (the light-sensitive cells in your eye) that are most tightly packed away from the centre of your retina. 🙂

[vlaiv]

Both yes and yes.

Yes, nebulae have color that one could see if light was intense enough. Second yes is for people coloring nebulae on purpose sometimes.

There are two main types of images from nebulae, regular "color" images, or something like this:

and then there are images of nebulae in narrow band imaging technique that uses false color - or something like this:

You will notice that these two images have different color but depict same object.

First image is so called RGB image and tries to mimic what we would see if somehow light from nebula would be strong enough to cause color sensation. For the most part - people don't really get exact color and that is mostly due to color balance and the way cameras work. If one tries to capture exact color then special care must be taken to calibrate color in images properly. Most astrophotographers don't do that and often boost their saturation and process their images in different ways.

In the end - real color would resemble image number one but would not be 100% the same.

Second image is colored differently on purpose. This is special method of recording of the image that targets specific gasses that compose nebula. Hydrogen, Oxygen, Sulfur and Nitrogen are often used.

Three different gasses are recorded and then color is assigned to each of them. In this case - colors don't really resemble anything real but are instead used to show where different gasses are inside nebula. It shows nebula structure better than regular color image.

 

[JOC]

FWIW if you haven't already found it check out this thread, esp. the pictures on the first page and the explanations it has some great information in it: