Comment: You've gotta love a tough Challenge!

 I have to admit to loving difficult Challenges... 

... and this one was (I admit) harder than I expected... and much more fun!

A sundial at 7:30AM in Southern California, as seen on one of my runs near Bolsa Chica.

A Cautionary Tale for Teachers and Authors: 

When I wrote last week's Challenge, I actually had found a great resource to answer the "from a shadow figure out the time and date?" I had actually done the work to compute it, and--for once!--I was ahead of the curve.  

But as I was writing up my Answer last week, I did what I always advise people to do:  I looked for a separate source to validate my answer. 

Good news / Bad news:  I found a couple of other ways to figure the answer!  Hurrah!  

BUT... they all gave somewhat different answers!  

I love problems like this. (And I freely admit that this drives most people crazy.  But insight lives in the difficult questions--anyone can solve the easy Challenges!)  

And so... I'm still working away on the Answer to the Challenge SearchResearch Challenge (9/22/21): Time and date from a shadow?

No, Remmij, I don't have the blahs.  I'm actually working on a good answer to a simple problem... and one that I am sure is correct.  

So, if you're a teacher or a writer, here's a maxim:  Check your work... including the cross-checks that you would normally do.  And, when you find multiple different answers, make sure you understand why they differ.  It will make your explanations plausible to your students and readers.  

Still searching!