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?
By eye, of course. What do you think would be the difficult part?
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.
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.
How wide would a sunspot appear without magnification?
They can get to be pretty big:
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.
Gee, I wonder when you can observe the sun by the naked eye?
Thanks for the mockery instead of trying to help me understand something.
I’m done.
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:
It’s just the image downsampled to 25x25 pixels and then upscaled. But you would need a way of reducing the brightness.
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.
Maybe with a pinhole camera. This web page Introduction to the Camera Obscura - National Science and Media Museum blog(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.”
Please point to the sun spot in your pictures. Thanks.
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.
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?
Are you going to pretend this is the same picture you shared earlier?
I concur with Typo_Knig: A pinhole camera seems most likely.
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.
No. I was just demonstrating previously that it is possible to observe the sun by the naked eye without the use of special equipment.
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).
It would not surprise me if some ancient sun observers did suffer eye damage due to their studies.