B Is it possible to see sunspots with the unaided eye?

[BenAS]

This has been bugging me for a while, I'm not sure what I saw exactly. A few months ago there was some thin clouds blowing past the sun, obscuring it to the point you could easily look at the disk with the unaided eye. There was a dark spot, that looked like a sunspot as seen in filtered pictures of the sun. The clouds were blowing by fast and the spot didn't change position on the sun for 10-15 minutes I was watching it. Is a sunspot a rational explanation for it?

 

[phinds]

calling @davenn

 

[russ_watters]

Yes, but they have to be ginormous.

 

[fresh_42]

Unlikely. More likely is that you already damaged your retina, which produces the dark point. I strongly recommend NOT to look into the sun with unprotected eyes, and sunglasses are NOT sufficient, clouds even less. This is a sure way to burn your retina or parts of it with no chances to ever get recovered. DO NOT DO THIS!

 

[BenAS]

Unlikely. More likely is that you already damaged your retina, which produces the dark point. I strongly recommend NOT to look into the sun with unprotected eyes, and sunglasses are NOT sufficient, clouds even less. This is a sure way to burn your retina or parts of it with no chances to ever get recovered. DO NOT DO THIS!

I would think the dark point would move around with my vision (like floaters, which I have). Not stay exactly the same place on the sun for 10-15 minutes

Edit: I was not staring at it the whole time, I kept looking back at it when it wasn't too bright. But wise advice nonetheless

 

[Bandersnatch]

Do you know the exact date it happened?

 

[BenAS]

Do you know the exact date it happened?

No, unfortunately not.

 

[Andy Resnick]

This has been bugging me for a while, I'm not sure what I saw exactly. A few months ago there was some thin clouds blowing past the sun, obscuring it to the point you could easily look at the disk with the unaided eye. There was a dark spot, that looked like a sunspot as seen in filtered pictures of the sun. The clouds were blowing by fast and the spot didn't change position on the sun for 10-15 minutes I was watching it. Is a sunspot a rational explanation for it?

Yes, sunspots have been viewed with unaided eyes for millennia:

https://www.windows2universe.org/sun/activity/sunspot_history.html
http://chandra.harvard.edu/edu/formal/icecore/The_Historical_Sunspot_Record.pdf

 

[OmCheeto]

According to Stavros you can:

...

When I saw it it was still about the size of Jupiter (I caught it on the verge ...). So no need to have a falcon eye. It was expected (to be visible by "naked eye").

If I can still see it today (meaning tomorrow July 15) (with just the solar glasses) I'll probably change my profile name ... to "falcon" ...

A fun experiment I just devised, to see if you can see sunspots with your naked eye:

1. Pull up Stavros's image of the sunspots on your computer.

2. Aim it towards a distant location.
3. Measure the diameter of the sun on your monitor.
4. Walk as far away from your monitor as possible.
5. Start walking towards your monitor, until you can just "sense" that the sunspots are present.
6. Measure the distance to your monitor.
7. Do a bunch of fancy maths, and determine the angular resolution of your eyes. [3]
8. Google the angular diameter of the sun as viewed from Earth. [1]
9. If the angular resolution of your eyes[2] is greater than the angular diameter of the sun, then you cannot see sunspots.

ps. I cannot see sunspots with my naked eyes. Though, I'm old, and accept the fact that all of my equipment is wearing out, and am not ashamed to admit it.

[1] 32 arc-minutes (sun as seen from earth)
[2] 100 arc-minutes (Om has to magnify the sun 3 times to see sunspots.)
[3] I would do this for you, but I did the maths long ago in the "Ceres" thread, where I plugged the equations into a spreadsheet, as I knew it would come in handy one day, as I can't remember my sines from cosines for squat. But, I'm sure it wasn't that hard.

 

[Stavros Kiri]

The one I saw back on July 13 was huge. But still I was wearing solar eclipse glasses (no magnification due to other instruments).

It's even visible with naked eye, solar glasses of course ! Just got the chance to see it ...

With totally naked and unaided eye it's a bad idea! @fresh_42 's warning is an important one!

Subsequent sun spots have been much smaller and I haven't been able to see them with just the solar glasses - I admit it too.
The latest ones (around eclipse time) are just about visible with binoculars (I used 12×30 even today) [&filter], if you focus properly and you know where to look ...

 

[davenn]

Is a sunspot a rational explanation for it?

yes a good explanation

Yes, but they have to be ginormous.

I agree with Russ ... yes but they have to be pretty large ones

No, unfortunately not.

That is unfortunate as I have a full set of data that goes back many years

you can't even give a month and part of that month ... I don't need the specific day

I would think the dark point would move around with my vision (like floaters, which I have). Not stay exactly the same place on the sun for 10-15 minutes

that is true ... sunspot is most likely reason

Dave

 

[BenAS]

Thanks everyone for the comprehensive answers

 

[davenn]

Thanks everyone for the comprehensive answers

you didn't answer my Q

 

[BenAS]

you didn't answer my Q

Sorry it was so long ago, thinking more about it I think it was 2.5 years ago (from my memory of where I was working) best guess is February-March 2015 or earlier. That's the best I can come up with

 

[davenn]

Sorry it was so long ago, thinking more about it I think it was 2.5 years ago (from my memory of where I was working) best guess is February-March 2015 or earlier. That's the best I can come up with

ohhh ok ... in your OP you said a few months ago, hence why I questioned you

 

[BenAS]

ohhh ok ... in your OP you said a few months ago, hence why I questioned you

It was something I didn't think much about at the time, the eclipse (which btw was amazing) made me think about it again.