After careful examination of several practically-identical products and a thorough delve into reader reviews, I can finally make my long-awaited recommendation for a strap-on unicorn horn: the YanJie Shiny (~$10, Amazon).
Aside from the critical rainbow model, it comes in various colors, is adjustable, and has the all-important strap so it doesn't come off your head when under extended or vigorous use.
It is five inches long, made of polyester, and a buck or two more expensive than the competition. For an item so important, though, it's worth splurging.
"I am an 'average sized' adult and I wore this for a party," writes D.T. "it fit perfectly."
"Using for cosplay and cosplay only," reports Queen of the Succubi. "It is legit enough."
"We love it, dog hates it," cautions Daniel. "What more can I say."
If you know of a superior shiny rainbow strap-on unicorn horn, tell us about it in the comments!
YanJie Shiny Unicorn Horn [Amazon]
Someone on a crane captured this stunning video of a full circle rainbow. Unfortunately most of us never get a chance to see circle rainbows because the ground interrupts. Here's an explanation from Phil "Bad Astronomy" Plait in Slate:
...To see a rainbow, you face away from the Sun (180°), then look about 42° away from that point (180°–138°). The drops in an arc along that angle will then bend the light back toward you, and you get a rainbow, with the colors spread out a bit because they bend by different amounts.
Oh, wait. Did I say “arc”? Because technically, any raindrop 42° away from the anti-solar point (ooh, fancy science-speak again) will bend the light back to you. We see rainbows in the sky because in general the ground is close to you. When we look up toward the sky we see for a long way, and there are lots of raindrops along your eyeline that can add their light together to make the rainbow. When you look down, the ground gets in the way, there aren’t as many drops, and you don’t see a rainbow.
big_mac_heart_attack posted this gorgeous example of a "fallstreak hole" with a rainbow in a cloud formation over eastern Victoria, Australia. They are rare enough that some people think they are evidence of UFOs. Unfortunately, that isn't usually the case. From Weather Underground:
Read the rest
Fallstreak holes form in these high to mid-level (cirrocumulus or altocumulus) clouds which are comprised of tiny water droplets that are below the freezing temperature but have not yet frozen (called supercooled water droplets). Airplanes passing through the cloud help the supercooled water droplets freeze. Air expands and cools as it passes over the wings and the propellor blades, decreasing the ambient temperature just enough to allow the droplets to freeze. The ice crystals grow and start to fall, while causing the water droplets around the ice crystals to evaporate. This leaves a large hole in the cloud with brush-like streaks of ice falling below it.
The physics blog Skulls in the Stars has answers to your rainbow-related questions. Among the fascinating things we learn here — each color in a rainbow represents the light reflected by a separate group of raindrops; skydivers can see circular rainbows; and the famous double rainbow happens when light bounces off the inside of a raindrop not just once ... but twice. Read the rest