# 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:** 20\ **Page:** 1
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [May 11, 2024, 1:39am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/1 "2024-05-11T01:39:19Z")
According to the Wikipedia article on sunspots, they were first observed by Chinese astronomers before 800 BC, and by western astronomers around 300 BC. How? how could a sunspot be observed without a telescope? > [@](#): > > The earliest record of sunspots is found in the Chinese _[I Ching](https://en.wikipedia.org/wiki/I_Ching)_, completed before 800 BC. The text describes that a _dou_ and _mei_ were observed in the sun, where both words refer to a small obscuration.[[7]](https://en.wikipedia.org/wiki/Sunspot#cite_note-Xu-7) The earliest record of a deliberate sunspot observation also comes from China, and dates to 364 BC, based on comments by astronomer [Gan De](https://en.wikipedia.org/wiki/Gan_De) (甘德) in a [star catalogue](https://en.wikipedia.org/wiki/Star_catalogue).[[8]](https://en.wikipedia.org/wiki/Sunspot#cite_note-8) By 28 BC, Chinese astronomers were regularly recording sunspot observations in official imperial records.[[9]](https://en.wikipedia.org/wiki/Sunspot#cite_note-9) > > The first clear mention of a sunspot in [Western literature](https://en.wikipedia.org/wiki/Western_literature) is circa 300 BC, by [ancient Greek](https://en.wikipedia.org/wiki/Ancient_Greece) scholar [Theophrastus](https://en.wikipedia.org/wiki/Theophrastus), student of [Plato](https://en.wikipedia.org/wiki/Plato) and [Aristotle](https://en.wikipedia.org/wiki/Aristotle) and successor to the latter.[[10]](https://en.wikipedia.org/wiki/Sunspot#cite_note-10) > > The earliest known drawings of sunspots were made by English monk [John of Worcester](https://en.wikipedia.org/wiki/John_of_Worcester) in December 1128.[[11]](https://en.wikipedia.org/wiki/Sunspot#cite_note-StephensonWillis1999-11)[[12]](https://en.wikipedia.org/wiki/Sunspot#cite_note-12) ---
**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, 1:42am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/2 "2024-05-11T01:42:36Z")
By eye, of course. What do you think would be the difficult part? ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [May 11, 2024, 1:43am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/3 "2024-05-11T01:43:26Z")
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. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [May 11, 2024, 1:44am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/4 "2024-05-11T01:44:03Z")
If you can bring the brightness down, the big ones can easily be seen with the naked eye. How they accomplished that I’ve no idea, but perhaps they could use a reflection off a dark surface like obsidian. ETA: Or just use it as a solar filter, since it’s slightly translucent. Though it might scatter the light too much for that. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [May 11, 2024, 1:51am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/5 "2024-05-11T01:51:01Z")
How wide would a sunspot appear without magnification? ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [May 11, 2024, 1:57am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/6 "2024-05-11T01:57:31Z")
They can get to be pretty big: [![](https://images.fineartamerica.com/images-medium-large/large-sunspot-group-sohoesanasa.jpg) ](https://images.fineartamerica.com/images-medium-large/large-sunspot-group-sohoesanasa.jpg) Note that the sun is about 0.50 degrees across, while the angular resolution of the eye is about 0.02 degrees. So it’s more than enough for large spots. And even the smaller ones will be seen as being a slightly dim area, even if they look a little fuzzy. ---
**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, 2:52am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/7 "2024-05-11T02:52:24Z")
Gee, I wonder when you can observe the sun by the naked eye? [![](https://upload.wikimedia.org/wikipedia/commons/a/a4/Anatomy_of_a_Sunset-2.jpg) ](https://upload.wikimedia.org/wikipedia/commons/a/a4/Anatomy_of_a_Sunset-2.jpg) ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [May 11, 2024, 2:53am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/8 "2024-05-11T02:53:43Z")
Thanks for the mockery instead of trying to help me understand something. I’m done. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [May 11, 2024, 3:02am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/9 "2024-05-11T03:02:22Z")
This is a _very_ crude approximation since the eye doesn’t have pixels in any normal sense, and actually can see _finer_ detail than the resolution would suggest, but this is _something_ like the level of detail you’d see from the image above: [![Imgur](https://i.imgur.com/GkLWzwn.png "imgur.com") ](https://imgur.com/GkLWzwn) It’s just the image downsampled to 25x25 pixels and then upscaled. But you would need a way of reducing the brightness. ---
**Author:** ![nearwildheaven](https://avatars.discourse-cdn.com/v4/letter/n/90db22/32.png) [@nearwildheaven](https://boards.straightdope.com/u/nearwildheaven)\ **Post date:** [May 11, 2024, 3:16am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/10 "2024-05-11T03:16:32Z")
After glass was invented, it was smoked (i.e. coated with soot) and they could observe the sun that way. I’ve done it myself, although it’s not recommended for general use. ---
**Author:** ![Typo\_Knig](https://avatars.discourse-cdn.com/v4/letter/t/cdc98d/32.png) [@Typo\_Knig](https://boards.straightdope.com/u/Typo_Knig)\ **Post date:** [May 11, 2024, 3:45am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/11 "2024-05-11T03:45:10Z")
Maybe with a pinhole camera. This web page [Introduction to the Camera Obscura - National Science and Media Museum blog](https://blog.scienceandmediamuseum.org.uk/introduction-camera-obscura/#:~:text=The%20history%20of%20the%20camera%20obscura&text=)(The%20name%20’camera%20obscura’,scholar%20Alhazen%20in%20about%201030. says “This ability of a pinhole to form an image appears to have been known to the Ancient Chinese as early as the 4th century BC and was first described outside China by the Arabian scholar Alhazen in about 1030.” ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [May 11, 2024, 5:55am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/12 "2024-05-11T05:55:08Z")
Please point to the sun spot in your pictures. Thanks. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [May 11, 2024, 5:57am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/13 "2024-05-11T05:57:28Z")
The natural thing to do is go back to the original source and see what the astronomers in question actually wrote. But I clicked on some of your links and they do not mention anything suggesting they used any artificial aids rather than just take advantage of favorable conditions (cloud, haze, etc.) making it possible for the unaided eye to discern sunspots through the Sun’s glare. ---
**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, 6:09am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/14 "2024-05-11T06:09:56Z")
> **[Sunspot at Sunset](https://bigthink.com/articles/sunspot-at-sunset/)** > > A sunset captured in Switzerland featured a sunspot so large it was visible to the naked eye. [![](https://bigthink.com/wp-content/uploads/2014/01/origin-178.jpg) ](https://bigthink.com/wp-content/uploads/2014/01/origin-178.jpg) > In the image above, a sunset captured in Switzerland featured a sunspot so large it was visible to the naked eye. You need me to draw an arrow? ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [May 11, 2024, 6:50am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/15 "2024-05-11T06:50:20Z")
Are you going to pretend this is the same picture you shared earlier? ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [May 11, 2024, 6:55am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/16 "2024-05-11T06:55:23Z")
I concur with **Typo\_Knig** : A pinhole camera seems most likely. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [May 11, 2024, 6:55am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/17 "2024-05-11T06:55:33Z")
The sun shining through any small-enough opening, like a hole in a curtain or shutter, can leave a clear disc image on a flat surface like a wall (think of this as a “natural” pinhole camera, as referenced by @Typo_Knig.) I’ve seen sunspots this way in my own bedroom. ---
**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, 8:13am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/18 "2024-05-11T08:13:32Z")
No. I was just demonstrating previously that it is possible to observe the sun by the naked eye without the use of special equipment. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [May 11, 2024, 8:18am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/19 "2024-05-11T08:18:52Z")
I don’t think the sun would look like your picture to the naked eye. Note how dark the sky surrounding it is. I have seen sunsets and I have never seen one that looks like that to my eye. Maybe the sunspot would be visible to the eye but, in general, I try not to look directly at the sun; even at sunset (a short glance maybe). ---
**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, 8:46am UTC](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402/20 "2024-05-11T08:46:37Z")
It would not surprise me if some ancient sun observers did suffer eye damage due to their studies. [Next page](https://boards.straightdope.com/t/how-were-sunspots-observed-prior-to-telescopes/1001402.md?page=2)