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• #75652
the true colour of the star / galaxy
Is it really the true colour, not a colour which some astronomer has picked, to look pretty?
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• #75653
Weird old guy in a tracksuit with inexplicable status in the BBC is protected child rapist. The Savile/Westwood comparisons just get worse.
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• #75654
Actually reasonably smart.
The Labour one was confidence in Johnson. Tories either had to vote for no confidence or effectively back Johnson.
This one is confidence in government, which I suspect the government as a whole has.
Gets round the "scared to have a vote" claims and most people won't care about the nuance.
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• #75655
Exactly, Labour's VoNC was a bit of a stunt with its wording and the Cunt party have called their bluff.
It won't backfire on them as no Tory is going to vote themselves out of a job, especially with the list of ayes/nays published in full.
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• #75656
Looks like they are playing politics…
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• #75657
:-p
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• #75658
Yes
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• #75659
Sunak's odds are three times longer than they were yesterday. He's down with Truss at 3 to 1.
Mordaunt is even money.
Nobody else is better than 14 to 1 https://www.oddschecker.com/politics/british-politics/next-conservative-leader
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• #75660
I am afraid you are getting confused with astrophotography and spectroscopy, but even with that in mind this is a bit of a silly question. I referred to hydrogen absorption spectra, and the absorption lines fall very comfortably within the visible spectrum.
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• #75661
If you look out of the window of your spaceship, would you ever see these colours?
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• #75662
I'm not sure I really understand what you're getting at, but you seem to be asking me if the human eye is capable of observing light in the visible spectrum? If you are asking me that question... then yes.
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• #75663
I mean if you wanted to stare at a star you wouldn't see much as your retinas burn out.
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• #75664
I admit the redshift/blueshift thing foxes me as I can't remember which is coming closer and which is moving away unless I think about a flame, where it's low energy at red and high energy at blue. I expect to be told that I've got it backwards now.
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• #75665
You’ve got it right.
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• #75666
Say you were in a spaceship and you were near enough to the beautiful gas clouds in the James Webb photos to see them out of the window. Would the colours look the same as the colours in the photos?
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• #75667
I think I know what you're getting at (or maybe read the same thing) which says that these photos you see are somehow enhanced. I thought that was just because it was very faint though, rather than false / dramatised colours.
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• #75668
They’re possibly asking if the images are truely representative of the human visible emission spectrum I’m guessing? Or is it false coloured from all EM spectrum detected?
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• #75669
I think those were taken in the infra-red spectrum.
Here is a good explanation why false colours are used even for visible spectrum images
https://www.gxccd.com/art?id=453&lang=409 -
• #75670
On that note, most images taken are enhanced for scientific publication. If they don’t Cameras/detectors will linearly correlate photon intensity with pixel intensity. In reality that’s very different to how our eyes work, as we’re very bad at deciphering linear changes of intensities but instead very good at gathering information from a huge range of brightnesses.
So if you were to represent photon intensity in an image you’d see very little as to accommodate the brightest object you’d see nothing else. So there has to be some processing to make what’s detected look like what we see
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• #75671
If something is red-shifted, it's moving away. If it's blue-shifted, it's coming closer. I always think that if someone's angry, they tend to be red and you want them to go away, if they're blue, they're chill and they want to come in close for a hug.
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• #75672
Just like Doppler with a siren.
Coming towards you: higher pitch = higher frequency = blue
Going away: lower pitch = lower frequency = red
Why is something coming towards you higher energy? Imagine someone is 10m away from you, and throws a ball at you every second for 10s. Imagine the ball travels at 1m/s.
If the thrower stands still, you get hit with 10 balls in 10 seconds, after an initial 10 second wait. This is the "true" frequency as seen by the thrower.
If the thrower is travelling away from you at 1m/s, the first (or zeroth) ball takes 10s to get to you, the second takes 11s (as the thrower is now 1m further away), the third takes 12s etc. until the 10th ball, which takes 20s. But the 10th ball also leaves 10s after the 1st, so you've see 10 balls in 20s total. The frequency is halved.
If the thrower is coming towards you at 1m/s, the balls are travelling at the same speed as the thrower, so you are going to be hit by 10 balls all at the same time (high frequency) after a 10 second wait - like a sonic boom.
Now instead of balls substitute power or wavelengths or whatever
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• #75673
If you were in a spaceship which was travelling at the same speed as the object you were looking at and it is emitting light in the visible spectrum, yes you will see it.
Galaxies will emit in the visible spectrum, but also in other wavelengths beyond the visible spectrum. It's the same with all celestial bodies - if you are looking at it and you're travelling at the same speed as it, you will see it as long as it emits in the visible spectrum.
What I was talking about before when I said "true colour" is this light it is emitting. The reason why as an observer a long way away probably won't see the true colour is because the expansion of the universe causes the objects to red-shift. Visible light then moves towards infrared and our eyes can't see that. So the "true colour" is correcting for this red-shift. If you're in a spaceship up close and moving at the same speed, you don't get the red-shift.
Sometimes astronomers will represent objects using false colour representation to demonstrate certain phenomena in a way that the layman can understand. If you would like an example of this, I would recommend googling "cartwheel galaxy xray vs visible". As your eye is unable to see x-rays, you would never be able to see the x-ray emissions from the cartwheel galaxy. To make it visible, you observe it with an x-ray telescope and then represent the x-rays as a visible colour.
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• #75674
Take it over here, you lot >>>>>>>>>>>>>>>>>>
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• #75675
Imagine the ball travels at 1m/s.
If the thrower is travelling away from you at 1m/sThe ball will never hit you...
I vaguely remember reading something about how if you play music (in time) with other people you’re basically time travelling because the internal processing time means that if you were truely hearing and reacting, everything would get slower and slower and/or out of sync. Maybe the same with any activity involving high levels of coordination between senses?