2 upvotes, 4 direct replies (showing 4)
View submission: Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science
When i see pictures of different nebula from hubble or jwst, would it look the same if i was looking at them with my own eyes from up close? Or are the images edited to show the different gases and dust?
Comment by nivlark at 14/09/2022 at 23:02 UTC
6 upvotes, 1 direct replies
They aren't "edited" in the sense that someone has gone into Photoshop and started drawing in extra information. Every feature you see in the images corresponds to real structure in the objects they depict.
JWST produces monochrome images from light with wavelengths human eyes cannot see. We take multiple images captured using filters that allow different wavelengths to pass through, and assign them to the red, green and blue channels of a visible-light colour image.
The way we choose which source wavelength is assigned to which colour is arbitrary, which is why these images are called "false colour". So the colours themselves aren't meaningful, but differences between colours still are: if a false colour image is brighter in red than blue, then whichever wavelength was assigned to red is also brighter for the real object.
Comment by dubcek_moo at 14/09/2022 at 22:44 UTC
3 upvotes, 0 direct replies
Sometimes looking through a telescope even here on Earth people don't see as bright colors as they see in photographs taken through telescopes. Your eyes have two detectors, rods and cones. When there are low light levels, you naturally don't see colors very brightly. Just making the image brighter would enhance the colors for your vision. You don't see things as they are. Your eyes are strange biological machines.
Comment by prappleizer at 15/09/2022 at 05:21 UTC
2 upvotes, 1 direct replies
Certainly not with JWST. it observed in wavelengths the eye can’t see at all. We then map those brightnesses into colors we do have just to visualize.
For Hubble, if the images are constructed from the right bands for the right rest frame emission, it *can* look like what you’d see by eye. But the eye is not actually very sensitive and can’t pick up photons in “long exposures” the way telescopes can. So a well-weighted, optical, HST image of a nearby nebula might look like what you’d see if you were floating in space (no light pollution), magnified (you had 2.4 meter wide eyes), and could “expose” longer Than our eyes. In reality, looking at most of these things would come out to “gray”, with some features (mostly structural) coming through. Doesn’t mean the images aren’t real — just means our eyes aren’t as good as hubble :)
Comment by Wooden_Ad_3096 at 14/09/2022 at 22:18 UTC
1 upvotes, 1 direct replies
The JWST takes pictures in infrared, so it would look different.
And yes, they are edited to be more colorful for two reasons:
1. To differentiate between gasses.
2. To get more funding.