# How were sunspots observed prior to telescopes? **URL:** \ **Category:** Factual Questions\ **Created:** [May 11, 2024, 1:39am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402 "2024-05-11T01:39:19Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [May 11, 2024, 9:08am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/21 "2024-05-11T09:08:51Z")
> [@Whack-a-Mole](#): > > I don’t think the sun would look like your picture to the naked eye. Note how dark the sky surrounding it is. The sun is still very, very bright, even with its light attenuated during sunset. If you adjust a camera such that you get the proper exposure of a sunset, then the surrounding sky will be underexposed, i.e., too dark. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 11, 2024, 9:39am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/22 "2024-05-11T09:39:31Z")
**Moderator Note** > [@Terminus\_Est](#): > > Gee, I wonder when you can observe the sun by the naked eye? Given that the sun is bright enough that it is painful to look at, and also is fairly small when viewed by the naked eye, it’s a valid question and does not deserve mockery. You have been around here long enough to know that belittling the OP and mockery are not acceptable in FQ. Stick to the facts in this forum. No warning issued, but do not do this again in FQ. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 11, 2024, 12:31pm UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/23 "2024-05-11T12:31:08Z")
> [@Northern\_Piper](#): > > After all those warnings not to look at the sun directly? I would have thought that the sun was just too bright to make out details like that by eye. Telescopes are irrelevant or worse for that. If you look at the Sun with your naked eye, you’ll get a small damaged spot on your retina. If you look at the Sun through a telescope, you’ll instead get a large damaged spot on your retina. Galileo did indeed go blind, presumably due to his observations of the Sun through his telescope. ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [May 11, 2024, 1:20pm UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/24 "2024-05-11T13:20:22Z")
> [@Whack-a-Mole](#): > > I don’t think the sun would look like your picture to the naked eye. Note how dark the sky surrounding it is. That picture was obviously taken at night. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [May 11, 2024, 4:44pm UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/25 "2024-05-11T16:44:40Z")
On my phone, that photo of the sun is about an inch across. That means that when holding the phone at a normal reading distance, the image is about 50 to 100 times larger than how the actual sun appears. Being able to see a sunspot in that image doesn’t really prove anything about being able to see a sunspot when actually looking at the sun. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [May 11, 2024, 10:02pm UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/26 "2024-05-11T22:02:28Z")
I expect that some ancient observations were made during solar eclipses. I know when I saw the total eclipse back in April I saw two very clear solar prominences during totality. Granted, far enough back no one would know what those were, but observations were possible. How far back in history were places like India or the Central American civilizations with good calendars and math skills predicting eclipses? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 13, 2024, 12:39am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/27 "2024-05-13T00:39:58Z")
Maybe not. > **[Galileo, solar observing, and eye safety](https://aty.sdsu.edu/vision/Galileo.html)** > > Galileo, solar observing, and eye safety Everyone should read this. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 13, 2024, 2:13am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/28 "2024-05-13T02:13:54Z")
A very thorough article; thank you. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 13, 2024, 8:38am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/29 "2024-05-13T08:38:55Z")
One other way in which the disc of the sun could have been observed is through thin, even cloud or mist - this does disperse light a bit, but there are moments on cloudy/misty days when the sun appears as a relatively well-defined pale disc of light, through an overcast sky which does not appear\* sufficiently bright to cause pain or a blink reflex. \*NB: I am NOT saying that it’s safe to stare at the sun under these conditions - it quite likely isn’t, as UV light penetrates cloud, however, people in ancient times may not have understood this. ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [May 13, 2024, 8:56am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/30 "2024-05-13T08:56:00Z")
Of the hundreds of sunsets I’ve seen, a handful have been dim enough to potentially see sunspots. I’ve never seen one yet. But a large sunspot more than about half an arcminute across should be visible under ideal circumstances. This one might have been visible at sunset without filters, but the article does (correctly) tell you to use eye protection. > **[A massive sunspot is currently visible to the unaided eye. Here's how to see...](https://www.space.com/sun-sunspot-unaided-eye-how-to-see-safely)** > > The new sunspot is 4 times the size of Earth. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [May 13, 2024, 2:45pm UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/31 "2024-05-13T14:45:18Z")
This seems like a good time to plug a very valuable internet resource for solar weather news, reports and roughly current images. It’s compiled info from various places but most people in this thread will find something of interest. The dev is a Canadian amateur radio operator and I’m proud to have kicked him a few bucks to keep it going. [https://solarham.com/](https://solarham.com/) ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [May 13, 2024, 5:04pm UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/32 "2024-05-13T17:04:31Z")
The next year or two may be the best time to easily see sunspots, then you’d have to wait another decade or so. (However you do it) [https://www.swpc.noaa.gov/products/solar-cycle-progression](https://www.swpc.noaa.gov/products/solar-cycle-progression) BTW the lower suspot numbers areound 1800 are concurrent with a global cooling. I guess Galileo saw them just in time… [https://www.researchgate.net/profile/Maximiliano-Rocca/publication/348417878/figure/fig2/AS:979210793414661@1610473454967/Data-of-sunspot-numbers-from-1600-to-the-present-time-Data-from-which-curve-is-plotted.png](https://www.researchgate.net/profile/Maximiliano-Rocca/publication/348417878/figure/fig2/AS:979210793414661@1610473454967/Data-of-sunspot-numbers-from-1600-to-the-present-time-Data-from-which-curve-is-plotted.png) ---
**Author:** ![Kelevra](https://avatars.discourse-cdn.com/v4/letter/k/97f17d/32.png) [@Kelevra](https://boards.straightdope.com/u/Kelevra)\ **Post date:** [May 13, 2024, 6:38pm UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/33 "2024-05-13T18:38:27Z")
About 20 years ago I was in West Virginia on a very foggy morning. I could look directly at the sun without issue (wearing polarized sunglasses). I could see sunspots. I posted about it previously. > [@Did I see sun spots?](https://boards.straightdope.com/t/did-i-see-sun-spots/767033/1): > > This happened maybe 10 years ago. (I could probably dig up the exact date if it’s important.) I was traveling with a co-worker in West Virginia. Around 10 a.m. we were driving (me in the passenger seat) in just enough clouds that the sun was not much more than a bright disc. With my polarized sunglasses I could look directly at the sun. It seemed to me that I could see sun spots. My co-worker was driving and other than noting that he too could look at the sun, he didn’t want to take his ey… ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [May 16, 2024, 4:09am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/34 "2024-05-16T04:09:46Z")
WARNING: STARING AT THE SUN WITHOUT A PROPER FILTER CAN CAUSE PERMANENT EYE DAMAGE, EVEN IF IT SEEMS DIM ENOUGH TO LOOK AT. DON’T DO IT. I have seen a sunspot with my naked eyes. I believe it was in the summer of 1989, and I was driving west into California. As I was approaching LA a couple of hours before sunset, the sky was fairly clear, but I suppose the smog was enough of a filter that I could look directly at the Sun, and I did see a sunspot. I only looked long enough to see it, then I looked away and back briefly because I couldn’t really believe what I’d seen. I wear glasses and I have been examined by an ophthalmologist several times since then. I’ve asked if there was any damage, and the answer is always “No.” However, since that trip to California I bought some #14 welder’s glass and now I always use it. I advise everyone to do the same. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [May 16, 2024, 6:59am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/35 "2024-05-16T06:59:03Z")
However, I would suggest not wearing welders’ goggles while driving. [Previous page](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402.md?page=1)