The way aurora are seen, what is going on please?

[JOC]

So I've just had an interesting discussion with my Bro who Did see that spectacular aurora display last week.  He and a group of friends were at a festival.  However, he reports that without exception all those watching reckonned that they only 'naked eye; saw the spectacle showing as white lights in the sky and that it took photographing them with only some of the mobile phones (the others wouldn't take the display at all) before they saw all those spectacular colours.  Does that sounds par for the course, do the eyes only see these things in whites and grey and if so what is going on please?  I guess perhaps it is this persistance of vision that a camera gives - like when you have a longer exposure and do some stacking to see more stars.   I assumed that we would see all the spectacular colours with the naked eye, but on bro's report that would not appear to be the case??

[Carbon Brush]

Take a look here....

 

[JOC]

53 minutes ago, Carbon Brush said:

Take a look here....

Really interesting - and thanks for the pointer to that thread.  Perhaps I don't feel quite so disappointed to have missed it, I thought people were seeing all the colours.  However, it does make me wonder if my mum and I saw something the next night.  We were out looking at the right time and either side of the moon (which was a tiny sliver) it was as though there were clouds wisps appearing and disappearing in arcs around the edges of the moon.  I wonder if I had known to hold up a phone if there would have been the colours.

Edited May 14 by JOC

[Carbon Brush]

I wonder if years ago (when I knew even less about the sky than I do now) I missed and gave up on aurora viewing for the same reasons.
Nothing obvious to see.
A primitive (20 yers ago) digital camera has awful sensitivity. Prior to this, using a film camera doesn't yield instant pictures!
Should I have snapped away in the dark with a film SLR hoping to view coloured pictures days later?

[Shimrod]

9 minutes ago, JOC said:

Really interesting - and thanks for the pointer to that thread.  Perhaps I don't feel quite so disappointed to have missed it, I thought people were seeing all the colours.  However, it does make me wonder if my mum and I saw something the next night.  We were out looking at the right time and either side of the moon (which was a tiny sliver) it was as though there were clouds wisps appearing and disappearing in arcs around the edges of the moon.  I wonder if I had know to hold up a phone if there would have been the colours.

We definitely saw the colours where we were - but if you are competing with light pollution (or a bright moon) then you may well see more of a fuzzy grey band. My avatar is a shot I took in Iceland in 2015 - it was a strong storm and the greens were very vivid, along with the bands of purple. The camera enhances the image, but it is not dissimilar to what I was seeing with the naked eye on that occasion as well.

Edit: Of course the strength of the CME matters as well. A kp index of 2 in Iceland is not much more than a fuzzy grey band and is simply not visible (with or without camera) this far south.

Edited May 14 by Shimrod

[Bruce Leeroy]

Initialy I looked up to zenith and I could see grey cloud then noticed the cloud was pointed and spread out in lines heading north, looking to the west seemed a little green and to the east a more noticeable red this seemed to continue as a trend, as I saw a colour then asked my daughter to confirm if a certain colour was noticeable to her and we where in agreement she is 26 i'm 53. Lying back and looking towards polaris I could swear I could see a mottled red flowing through the grey colour.

I live in Burscough, we decided to travel 2-3 miles towards Croston and was rather dissapointed thinking it must be fading but when we returned home the aurora was as strong as it was when we left.....watching into the early hours as it did fade I thought the colours where more noticeable as it lessened.

[JOC]

I think I will go and charge the tablet up, that is supposed to have decent onboard camera capability and I will have the large screen.  There is a posting elsewhere on SGL that suggests there is a chance of seeing it tonight around midnight?

[Shimrod]

4 minutes ago, JOC said:

I think I will go and charge the tablet up, that is supposed to have decent onboard camera capability and I will have the large screen.  There is a posting elsewhere on SGL that suggests there is a chance of seeing it tonight around midnight?

KP index is forecast for between 4-6 tonight so unlikely, but it is only a forecast and the actual strength can vary up or down (mostly down in my experience!).

Glendale app is a good one to see if others are reporting sighting of aurora, although it does get overwhelmed with traffic at times. https://aurora-alerts.uk/

https://www.swpc.noaa.gov/products/3-day-forecast

[JOC]

1 minute ago, Shimrod said:

Glendale app is a good one to see if others are reporting sighting of aurora, although it does get overwhelmed with traffic at times. https://aurora-alerts.uk/

Now that's a nice example of how the internet should be used 🙂

[saac]

We saw colours here in Fife with naked eye. Sure, no where near as vivid as with a camera/mobile phone but yes the colours were definitely visible by eye. Allowing your eyes time to dark adapt also made the colours more prominent.  It was also possible to detect movement in the aurora, not so much real-time just an awareness that the pattern had changed if one looked at a different part of the sky and then back again.  

Jim

Edited May 14 by saac

[niallk]

Strong green and pink visible naked eye in Bortle ~4 skies in Cork.

[TiffsAndAstro]

1 hour ago, Carbon Brush said:

I wonder if years ago (when I knew even less about the sky than I do now) I missed and gave up on aurora viewing for the same reasons.
Nothing obvious to see.
A primitive (20 yers ago) digital camera has awful sensitivity. Prior to this, using a film camera doesn't yield instant pictures!
Should I have snapped away in the dark with a film SLR hoping to view coloured pictures days later?

In my bortle 6 back garden, there were no aurora.

My 2 minute subs were full of magenta gradients.

Maybe I can use graxpert extract each subs background, save it, make a time lapse. Hmmmm

Edited May 14 by TiffsAndAstro

[Elp]

Depend on your local LP sky glow. I'm surrounded by LED lampposts in a Bortle 7 but looking directly up I could see the smooth lines forming into a tulip shape, they were so smooth that they couldn't have been cloud. As the activity intensified I could make them out to be a pink/red colour, even after levelling my eyes to be blasted by surrounding lights and then looking back up, clearly pink/red. To the west there was also a diagonal line running from the horizon and up towards the stronger activity, through a camera 1s exposure this was also streaked from one side of the line and had green/purple hues as well as the pink/red I could see. From a dark site no doubt I'd also see some green.

[Elp]

I've tried to darken this image to the visual perception I had, ignore the bottom part of the image, the top half is kind of what it was like (will depend on the type of screen you're looking on and how it's calibrated), this is the western form I just described above:

And a 1s camera exposure (different camera and lens), unedited, in fact it's a photo of my screen so the quality is even less:

Edited May 14 by Elp

[JOC]

It's most interesting, so what is the camera recording that our eyes aren't?  Is it just down to the longer exposure and more photons hitting the camera sensor (like when you use longer exposures and/or stack exposures) or is the camera actually seeing more light wavelengths than our eyes do in the same way that a mobile phone camera can show the infrared? light from the TV remote that you can't see with your naked eye.  

[mcrowle]

The anatomy of the eye is the difference, the rod cells being responsible for night vision but not seeing colour. Only the cone cells, for day vision, see colour. Therefore, the aurora only registers to our eyes in colour when it is bright enough. The camera sensor doesn't have that limitation, and colour is registered regardless of how bright the light is. No doubt I'm over-simplifying things, though 😃.

Regards, Mike.

[ONIKKINEN]

7 minutes ago, JOC said:

It's most interesting, so what is the camera recording that our eyes aren't?  Is it just down to the longer exposure and more photons hitting the camera sensor (like when you use longer exposures and/or stack exposures) or is the camera actually seeing more light wavelengths than our eyes do in the same way that a mobile phone camera can show the infrared? light from the TV remote that you can't see with your naked eye.  

Cameras are just more sensitive than our eyes, and they build up signal for the duration of the exposure. Even a one second exposure has significantly more light "gathered" than what the live view is naked eye.

There is also the fact that our dark adapted eyes see in monochrome, so if the aurora is faint enough for our eyes to stay dark adapted then colour is not seen.

[JOC]

5 minutes ago, mcrowle said:

The anatomy of the eye is the difference, the rod cells being responsible for night vision but not seeing colour. Only the cone cells, for day vision, see colour. Therefore, the aurora only registers to our eyes in colour when it is bright enough. The camera sensor doesn't have that limitation, and colour is registered regardless of how bright the light is. No doubt I'm over-simplifying things, though 😃.

Nope - that makes sense as does this:

6 minutes ago, ONIKKINEN said:

There is also the fact that our dark adapted eyes see in monochrome, so if the aurora is faint enough for our eyes to stay dark adapted then colour is not seen.

I recall a school homework for biology being asked to go home and watch outside whilst it got dark and then they we would be quizzed on what happened.  Not one class member spotted that colours disappeared and that only shades of grey remained due to only the rod cells firing in the eye due to the darkness.  However, that lesson, entirely explains why these explanations above also make sense 😄  It's amazing the odd stuff you can recall after far too long, but I remember the homework assignment.

[Elp]

The human eye typically sees at an equivalent camera frame rate between 25-60 FPS, the lower hence why video or film is done at 24 FPS (PAL) or 30 FPS (NTSC), animation input goes even lower sometimes with hand drawn typically at 12 FPS then recorded in twos to make up the 24 FPS (though now negated by computer software, but I believe Disney hand drawn still do 24 FPS native). So a camera set at anything longer than 1/25 s will have far more photons collected. Even when recording at 1/25 (25 FPS), the aurora video I've captured was far brighter than visual perception due to sensor sensitivity and similar to the photos I took.

[SteveNickolls]

2 hours ago, Shimrod said:

Glendale app is a good one to see if others are reporting sighting of aurora, although it does get overwhelmed with traffic at times. https://aurora-alerts.uk/

I can vouch for the usefulness of this App, it proved very helpful on the 10th-11th May giving real time updates on the display.

As regards actually seeing auroral colours with the Mark I eyeballs we all definately saw colour in the display here on the outskirts of Nottingham, the green and red especially though at times the colours faded to white depending no doubt how strong the display was at any one moment in time. I think that being out so long meant eyes could dark adapt.

On reflection I particularly liked how with the naked eye or a modest DSLR the whole event could be enjoyed.

Cheers,
Steve

[trailer]

The Glendale folk also have a Telegram account which gives real time updates. Here’s some from the weekend:

Edited May 14 by trailer

[saac]

31 minutes ago, SteveNickolls said:

I can vouch for the usefulness of this App, it proved very helpful on the 10th-11th May giving real time updates on the display.

On reflection I particularly liked how with the naked eye or a modest DSLR the whole event could be enjoyed.

Cheers,
Steve

 

I think this is a very valid point Steve makes.  The aurora last week was as much a once in a generation thing - the whole of the sky was covered (East to West , North to South) not just the usual curtain of light dancing in the Northern part of the sky. With moments like that I think it's important not to just keep a camera held to your face but to experience the whole effect.  I'm convinced that if I was ever lucky enough to see a total eclipse I wouldn't be taking photographs rather concentrating on the experience. Easy to say I guess, harder to do maybe but I got close to it last weekend, it was very moving.

Jim

[skyhog]

Definitely saw the colour red and hints of green.  What was particularly illuminating, if you excuse the pun, was how a hand held phone picked up so much colour and detail. Certainly a great subject to show where technology has come on that front.

[skyhog]

2 minutes ago, saac said:

I think this is a very valid point Steve makes.  The aurora last week was as much a once in a generation thing - the whole of the sky was covered (East to West , North to South) not just the usual curtain of light dancing in the Northern part of the sky. With moments like that I think it's important not to just keep a camera held to your face but to experience the whole effect.  I'm convinced that if I was ever lucky enough to see a total eclipse I wouldn't be taking photographs rather concentrating on the experience. Easy to say I guess, harder to do maybe but I got close to it last weekend, it was very moving.

Jim

Great point Jim. Recording events is very much baked into the DNA these days though, witness the sea of phones held aloft at your average concert....🙄

[russ]

3 minutes ago, skyhog said:

Definitely saw the colour red and hints of green.  What was particularly illuminating, if you excuse the pun, was how a hand held phone picked up so much colour and detail. Certainly a great subject to show where technology has come on that front.

To the naked eye we could barely see it from our bortle 7 skies. It was so faint I almost dismissed it. But when our neighbour to a photo with his phone we all stood back in amazement. I really should have got in a car and driven somewhere darker.