Hi!

Tomorrow, American business are (mostly) closed because the 4th of July hits on a Saturday, and we’re not ones to give up the vacation day. So I’m also taking tomorrow off — the Weekender hits a day early this year.

This Fourth of July is a special-ish one — it’s American’s semiquincentennial, which is a fancy way of saying “250th anniversary.” (“Centennial” means 100 years, “Quin” is a Latin prefix meaning five. So that’s five hundred. The “semi” cuts that in half, giving us 250. Math with Latin prefixes is dumb.) But, from a newsletter-writing perspective, it’s also a very slow period — probably the second slowest of the year after Christmas to New Year’s. People take off from work, go on vacations, and in general, don’t read email newsletters. So, like last year, I don’t have much to share here today.

So let’s talk about blue fireworks.

As fireworks are a very Fourth of July thing, and blue is one of the major colors of America, having blue ones is kind of important to our celebrations. But getting that blue — it’s tough. There’s a tricky chemical balancing act you have to figure out.

Fireworks get their colors from metal salts that glow when they’re heated. For blue, pyrotechnicians rely mainly on copper compounds. The catch is that copper only produces a vivid blue within a very narrow temperature range. If the firework burns too cool, the copper doesn’t emit much light and the color looks weak or washed out. But if it burns too hot, the copper compounds break apart, and instead of a brilliant blue you get a dull white or greenish glow. It’s a bit like trying to toast a marshmallow over a campfire: too little heat and nothing happens, too much and it burns before you get the result you want. If you’re a professional pyrotechnician, getting the blue right is a badge of honor.

And blue fireworks are a relatively new feature of these light shows. Before World War II, blue fireworks were often pale to the point of being almost white, kind of like how flavored seltzer has an essence of whatever it claims to taste like but is really just water with bubbles. Likely as a biproduct of the war, researchers learned a lot about how things blew up, and some noticed that different chemicals and oxidizers made for better blues. Our firework shows benefitted.

But the quest for big blue explosions continues. As recently as 2022, researchers were publishing papers on their efforts to get our rockets with blue glares bursting in air — and that research has hardly “solved” the issue. The quest for a blue fireworks for our 4th of July celebrations continues. Hopefully, if you’re in the U.S., you’ll see some good ones this weekend.

The Now I Know Week In Review

Monday: The Not-Quite-Healing Powers of Onion Soup: Soup is good food, but it’s also an ancient diagnostic tool.

Tuesday: Baseball’s Brady Bunch: A fun coincidence.

Wednesday: The Goalie Who Wouldn’t Stop: Neither rain nor sleet nor fog would prevent this man from tending his net.

And from 2012: Born on the 2nd of July… or August: Why today, July 2nd, may actually be America’s birthday.

Long Reads and Other Things

Here are a few things you may want to check out over the weekend:

1) “The Man Who Cried Goooooooooooal” (New York Times/gift link, 8 minutes, June 2026). The subhead: “The Telemundo announcer Andrés Cantor must train to deliver his famed scoring celebration for the World Cup, where he could call 20 games in about a month.”

2) “‘Navigating the unknown together’: me and my idiot AI boyfriend” (The Guardian, 20 minutes, June 2026). The first line of this story hooked me — in part because the text reads unprofessionally, I have to admit. “I received a text message from my editor: ‘Um, is it unethical to ask you to get an AI bf?? You can prob say no.’”

3) “Accidental Historian” (Bitter Southerner, 11 minutes, May 2026). The subhead: “Street photographer Ray Di Pietro focuses his work sharply on his adopted hometown of Nashville. With little fanfare, he has attracted tens of thousands of devotees His images are artfully composed, spontaneous, honest, and, well, kind.” The photos are wonderful.

Have a great weekend!

Dan