In the UK 21st december is the shortest day I think, too close to xmas.
An idea - Difference Day. A symbol for it -

You and dragon are very good when it comes to visual creativity . it must be the genes.
I do not have too many ideas about what people could do to understand what it is like to have AS. Maybe they could be talked to half the time so they never knew what was going on. Other people could wear masks over their faces so they could not see facial expressions and maybe people would only communicate to them briefly using e-mail or notes.
Whoa
This holiday isnt about others understanding who we are, it is about us understanding who we are which is far more important. i twould be about us celebrating our unique perspectives.
Helping people to understand others is important.
Umderstanding one's self is more important. Understanding one's self can make you more successful in your goal and happier.
We cannot just celebrate diversity. We all do that now. NT and aspie alike. BUt being aspie is a unique and different perspective that is what is challenging. I think providing a absasis of points like the 7 principles of kwanzaa that illimuniate the african life.
An idea that might help "them" understand "us" a little better:
Take the people who want to understand. Place them in cubicles with flickering light. At random intervals, replace whatever they're listening to with burst of high-volume white noise, or broadcasts in foreign tongues. Only let them communicate with others by keyboard - no telephone, no shouting to one another, only typing (which of course conveys information, but little emotional/societal context for said information). See if they can stand it for three or four hours. Then remind them that some of us live like this all the time...
I would happily use force to make them do it at least once. I have heard suggestions that normies should be made to spend a whole day or whatever listening to everything through hearing aids, which I heartily agree with after actually paying attention to how I hear things.