In this tutorial, we will generate an image of a black hole for a fraction of the budget of top world scientists. You don't even need a telescope for this; just go install GIMP for free! You can find lots of pictures of black holes online (e.g. from NASA). Some are real... others are not, like the ones we will make here.
See the HTML/CSS deployed on Github Pages.
Let's begin with dark space. Create an image with a single layer.
On a new layer, use the paint brush or the ink tool to make a reddish blob. Just get an overall shape you like. This is not an exact science! Here, I just "eye-balled" a color I liked. Alternatively, you could pull up an official black hole image and use the color picker tool to get a closer fit.
I then applied a Gaussian Blur (radius 100px on a 640x480 px image) to my reddish blob. I adjusted the opacity of the layer to get values closer to what I liked.
Next, I added an orange donut thing with the paint brush or ink tool like we just did with the reddish blob. I did this on a new (transparent) layer.
I then applied a Gaussian Blur, as before with the reddish block (radius 75px).
At this point, we're at the final stage of our scientific graphic production. I repeated the same procedure of adding layers, painting, and blurring.
You can experiment with blur radius values to find what looks right to you.
Finally, I added some final sparkly highlights...
Things here are of course very fuzzy. You can play around with your layers (opacity values, etc.) until you get a result you like. Behold, a black hole!
You can use your new black hole image(s) in applications like this curiosity driven graphic:
I generated an HTML document for this document using pandoc and
this CSS sheet by killercup (with a
couple small modifications).
pandoc README.md -c pandoc.css -so index.html