This gave me enormous joy on a rather tense day.
This gave me enormous joy on a rather tense day.
Taken on July 20 during a recent close pass grazing inside the rings, Cassini shot this amazing video of the southern lights on Saturn. Saturn and Jupiter, like Earth, are known to have auroras, but it is exceptionally difficult to photograph them, as they are so faint. Portraits of aurora are gorgeous, but they leave out the most fascinating piece — the wild, improbable rippling motion that they make as the magnetosphere moves.
I don’t have a fanfic to post today, on Fanfic Friday, so instead I’m going to finally give you the second installment of Why Is That In There? – this time looking at gum arabic!
As a traditional nerd, I am quite fond of Mountain Dew, and one of the ingredients puzzled me for a while. Why is there gum arabic in it? Gum arabic is actually found in a lot of soft drinks — and even in some hard ones, specifically wine. It’s also found in a lot of candies and pastes and frostings. Less surprisingly, it’s also found in chewing gum.
I first was exposed to gum arabic as a thing through art class. It’s used in a lot of paints, and I know it’s a natural glue. So why is it in drinks?
Well, a little thought maybe could have given me the answer, but I went and googled it instead. Its gummy nature means it makes an excellent emulsifier and an excellent thickener. This is actually also what it’s doing in paint — it helps the pigment mix with the solvent, allowing it to spread evenly through the paint, which is particularly important with water-based paints. So in Mountain Dew and other soft drinks, it helps the pigment, the flavors, the caffeine, and the sugar remain evenly distributed without separation, which is why you don’t have to shake it before you drink it — which, since it’s also carbonated, is a very good thing. 😉 In wine, it serves as slightly different purpose — it tends to bond with the particles that would precipitate out of the wine to create an unpleasant sediment (which is mostly dead yeast) at the bottom of the bottle. If added to the barrel, it will help the sediments come out much more quickly, so they can be captured and removed when bottling the wine. It is less common today than it was in the past, as more consistent materials are now available. (Maybe one of these days I’ll write about isinglass, which is a rather surprising ingredient when you first learn what it is.)
Oh, and why is it called gum arabic, you might wonder? Well, it comes from the sap of a couple of species of acacia trees, mostly ones found in the Sahel, a semiarid region south of the Sahara, but they’re also cultivated widely in Saudi Arabia, which is where Europeans first encountered it. It’s a completely natural, biodegradable, and edible adhesive and emulsifier that has been used since ancient times.
I’ve been offline for a while now; very busy at work and on the homefront, and so I’ve had no time to blog. Technically, I don’t have time tonight either, but I felt I had to check in for a change. Because there is something very beautiful that I have found, and you need to see it. It showed up on Astronomy Picture of the Day earlier this week, and I’ve been using it as sort of a stress reliever ever since. Do check it out. The data is nearly live; if you flip back through the past weeks’ worth, it’s fascinating to watch hurricanes form and then dissolve, to watch weather systems move over your home town, and to just see the *flow*. Click and drag to see different parts of the planet; use your mouse wheel to zoom in and out. Click the word “Earth” in the lower left corner to change to different data — default is surface wind speed, but you can also move upwards through the the atmosphere, or add overlays of surface temperature, relative humidity, chance of precipitation, and more. The “waves” option is quite hypnotic. Check it out!
Just because they don’t have webbed feet doesn’t mean they can’t swim. Check this out: a flying fox (giant fruitbat, or megabat) swimming like it ain’t no thing. It actually swims pretty well, and looks eerily like a stingray, using the membrane of its wings almost like a stingray’s fins. Obviously, it can’t ripple them quite as deftly, but the individual finger joints in the bat’s wing gives it remarkable agility in the air, and apparently also serves them pretty well in the water. Not that this is an ideal place for a bat. Unlike a waterbird, they can’t take off from the water. Bats can’t even take off from the ground; they have to climb up to get a bit of height first. But clearly they can get themselves to the side of the water if they have to.
It looks a lot less awkward than a swimming eagle. Eagles have basically the same body plan as most birds, and so when they sit on the water they look just like ducks. But since their feet are adapted into powerful gripping and tearing talons, they’re totally useless for swimming. So an eagle that has found itself stuck in the water (usually because they went for prey that was a bit too heavy to lift, but which they’re too stubborn to give up on) has to get itself to shore . . . a bit more awkwardly than a duck.
And then sometimes, after all that work, some other jerk eagle goes and robs the catch:
I’m gonna try out a new feature on this blog, called Why Is That There? In it, we’ll explore various strange and sometimes baffling ingredients in common products, and find out just why the ingredient is there. After all, manufacturers don’t add ingredients for no reason. It’s just not a reason that we, the general public, probably know.
We’ll start out with the one that first really piqued my interest in weird product ingredients: EDTA. I’m a cheapskate, so I use cheap shampoo: I wash my hair with Suave. And one of the ingredients is tetrasodium EDTA. It’s in nearly every shampoo, and a lot of body washes and hand soaps and laundry detergents as well. Sometimes its close cousin disodium EDTA is there instead, or the label might just say “EDTA”.
So what the heck is it?
EDTA stands for ethylenediaminetetraacetic acid. Try saying that five times fast. Or even once, for that matter. It’s in a special class of chemicals called chelators. A chelator (pronounced “key-late-or”) is a chemical that bonds in a particular way to metal ions. (The word comes from the Greek “chele”, which means “claw”. The idea is that the molecule is claw-like in the way it bonds to a metal ion.) Chelators bond extremely well to particular metal ions, so well in fact that you can use them medicinally to treat lead and mercury poisoning. However, they tend not to be especially fussy about *which* metal ions they go for, so chelation therapy should not be considered lightly — there is a very real risk of chelating out all the calcium ions in your blood, which would not only stop your heart, it would make it impossible to revive you with the zappy paddles since it would rob your heart muscle fibers of the calcium ions that they need to contract. That’s right: calcium is for way more than just strong bones. You need it to make your nerves and muscles work. That’s why your body will happily strip it from the bones if you’re running low; that’s far less critical.
Misused EDTA therapy has killed patients; it’s that dangerous. So why are we slathering this stuff on our heads? Are the guys at SC Johnson and Proctor and Gamble et all out to kill us?
Of course not. Turns out, EDTA is completely incapable of penetrating the skin, so it’s totally safe to slather it on our bodies. And there’s something really helpful it can do. It’s a chelating agent, and very good at stripping calcium. And guess what the most common culprit in hard water is? That’s right: calcium. Detergents don’t work well in hard water, so unless your water is really, really, ridiculously soft, you may find the shampoo rather disappointing. So years ago, shampoo manufacturers started including EDTA to soften the water as you go. And it works great! The calcium is stripped out of the water you’re using to wash your hair, the shampoo works much better, and you come away happy and smelling fresh. 😉
Did you know that rainbows aren’t just arcs? The rainbow is really a complete circle (well, a cone if we want to be really picky); the catch is that you’re usually not in a position to actually see the whole thing, because you need sufficient mist to reflect the sunlight back in just the right way all along the entire 42 degree circle of a rainbow. And since most rainbows are cast by distant mists and we’re usually standing on the ground, that means we usually don’t get to see even a full arc, let alone the bottom part of the bow.
rBut what if you were flying? What do birds see? Here’s an ultralight flight over the island of Oahu, with a magnificent full circle rainbow almost directly below them; if the sun is this high in the sky, this is rainbow you pretty much can’t see any other way than getting above the droplets.
This drone footage from Ireland shows a bow that is easily visible from the ground, starting on the ground and then rising up until the bow is complete. It’s a magnificent demonstration of how a rainbow changes as your perspective on it changes.
Actually, you don’t even have to be flying. All you need is a high viewpoint and a lot of mist. Niagara Falls, Ontario’s Skylon Tower provides a great high viewpoint next to a near perfect mist-maker, Niagara Falls:
And, y’know? I kind of lied about the “high viewpoint”. If the mist is close enough to you, just standing up is enough, if the sun is low. (Remember: the center of the rainbow is always directly opposite the Sun.) I don’t have any pictures of this, because I was driving at the time, but one day probably seven or so years ago I was driving back from my brother’s birthday party. A wicked storm had just blown through the area while we were in the party, so we were surprised to come out to find wet roads and a brilliant sun. Driving back, roadspray kicked up just the right kind of droplets, and alongside the car I could see the bottom of the rainbow. It was magical. Less magical was getting home and discovering what the hail had done to my siding, but I do wish I had pictures of that rainbow. You can simulate that sort of thing yourself this summer, when you go out to water your lawn, although it’s tough to get enough droplets to cast a full bow. Move the spray around, and “paint” more of the rainbow. It’s a small-scale way of demonstrating the same effect, and great fun for children. 😉