Among the Halloween candies this year are Sour Patch Kids Glow Ups Ghosts "with edible confetti that glows under blacklight". I only found them in large bags rather than the individually-packaged trick-or-treat size, which is just as well, since they might disappoint kids who don't have blacklights handy.

Beloved by nightclubs and fans of cosmic bowling, blacklights emit ultraviolet (UV) light. Although UV light isn't visible, when its high-energy photons hit things, some of those things absorb some of that energy and send back lower-energy photons. These lower-energy photons are visible, and we see them as fluorescent light.

I happen to have some UV flashlights, so I found some of the Glow Ups and tested them out. Sure enough, the sprinkles glow! The background white and orange candies (artificially flavored peach and orange) also glow, though not as strongly.

In both images, the most obvious feature are the bright green-yellow sprinkles that are glowing on the candies. There aren't actually that many sprinkles per candy, maybe around 10 or less?
Sour Patch Kids Ghost Glow Ups, illuminated by a (probably) 395 nm UV flashlight (left) and a 365 nm UV flashlight (right). The 395 nm image looks bluish because the flashlight emits some blue along with the UV. The 395 nm flashlight emits less blue, and also has a good filter that reduces the blue even more, really letting the colors shine through.

According to the bag, the sprinkles glow because they contain turmeric extract. Sure enough, powdered turmeric lights up under blacklight too.

The powdered turmeric glows bright yellow, while the candy sprinkles glow a little greenish.
Pile of powdered turmeric (right) next to the orange flavored Sour Patch Glow Ups, viewed with the 365 nm flashlight.

It didn't really come through in photos, but the sprinkles on the Sour Patch candy are glowing a lot more brightly per area than the original turmeric itself. They're also glowing a little bit more greenly. From papers I've read about the fluorescence of common food dyes, they glow more brightly when they're trapped in a highly viscous, almost glasslike, substance. The glowing molecules are being protected from other molecules that might bonk into them and steal their energy before Maybe the sprinkles are tiny flakes of hard candy, and that's why they glow so brightly.

If you hang around blacklights at least a little bit, you may be commenting to yourself that it's not that unusual for things to glow under blacklight. You may even be noting that if you have not just a flake of hard candy, but quite a large bit of it, then it really lights up under a blacklight.

It's a pile of candy. The Sour Patch Kids, with their white sugary/sour coating, are much duller than the other candies.
Sour Patch Kids Glow Ups, Jolly Ranchers (blue raspberry and watermelon), and Jelly Belly (classic 10-flavor mix), viewed under visible light.
The biggest, brightest thing in the pile is the watermelon Jolly Rancher, followed by some of the berry blue Jelly Belly beans.
The same candies, illuminated with a 395 nm UV flashlight.

In fact, some Jolly Ranchers and Jelly Belly beans light up considerably brighter than the special Sour Patch Kids Glow Ups. The specks on the Sour Patch Kids are the brightest things on the table, but since they're just tiny dots, they're overwhelmed by, for example, the vivid pink glow of a watermelon Jolly Rancher.

My verdict? If you want to impress people at a rave, go for whatever colorful candy tastes the best. I thought the two Sour Patch Kids flavors both tasted fake (they're artificially flavored) and they aren't spectacular enough to make up for it. Maybe if their entire surfaces were coated with the turmeric sprinkles, it would have helped! Wait, that gives me an idea

The candy is glowing red and the turmeric coating is glowing yellow. It's hard to say which is glowing more brightly.
Cherry Jolly Rancher coated in turmeric and illuminated with a 365 nm UV flashlight

Okay now I understand why they didn't coat the entire Sour Patch Kids in turmeric, and why the package says "You can't taste it!".

Bonus content for AI Weirdness supporters - I decided to find out what would happen if I illuminated Jolly Ranchers not with LED flashlights, but with lasers.

Laser merch store! Pretty sure at least some of the shirts glow under blacklight!

update: oh hell yeah the laser beams buttondown sure does, the laser beams glow very satisfyingly.

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