This isn't an earth science question so maybe it'll be closed, but I'll answer it fully because there's something you need to know about using content from Stack Exchange (and from Wikipedia and lots of other sources).
I created the illustration in order to answer the question Equinoxes and solstices: start of the season or mid-season?.
While the copyright is mine, everything posted to Stack Exchange is licensed CC-BY-SA (per the notice at the bottom of the page), unless stated otherwise or used illicitly. CC-BY-SA is the same licence that Wikipedia uses. The licence means (very roughly):
- You don't have to ask permission to use it for any purpose, however...
- You must attribute it to me (that's what BY means), and...
- You must license the new work under the same terms (that's what SA means).
That means that whatever you incorporate my work into must also be licensed under CC-BY-SA or a similar 'non-permissive' or 'copyleft' license. (This is why these licenses are often called 'viral'.) I don't think most people realize this when they use content from Wikipedia! You might not even be allowed to place you new work under this kind of license (e.g. in a non-open journal).
The good news is that I made a nice big CC-BY version just for you! So you can use this one with nothing more than attribution: