WHAT DO SILLY PUTTY AND TOMATO KETCHUP HAVE IN COMMON?

No, i'm not asking you a riddle, which in hindsight would have been a funnier way to start this post.
I spent nearly two hours browsing through various science majors that one could pursue and one called comparative planetology caught my eye. Upon further digging (comparative PALEONTOLOGY amirite?), I found out that this particular field focuses on studying mundane objects to observe celestial bodies (no I don't mean Beyoncé) in our solar system.

One of the major analogies that was being used to explain the various shapes of craters on the moons of planets like Jupiter is the viscosity of silly putty compared to that of ketchup. Silly putty is not just a fancy American word for Play-Doh. Silly putty is more elastic and does not hold it's shape so it is not suitable for sculptural work. In other words, it's "silly." And the thing that is common between silly putty and ketchup is that they are both non-Newtonian fluids, meaning that their flow properties are different from a Newtonian fluid a.k.a 'normal' fluid like water or oil.

A non-Newtonian fluid is a mixture that takes on properties of both a fluid and a solid. This is analogous to the wave-particle duality (something that is much closer to home and thus had a hand in helping me understand the non-Newtonian fluid enigma.)

If you want a more robust definition, this is what wikipedia has to say:
"A non-Newtonian fluid is a fluid with properties that differ in any way from those of Newtonian fluids. Most commonly, the viscosity (the measure of a fluid's ability to resist gradual deformation by shear or tensile stresses) of non-Newtonian fluids is dependent on shear rate or shear rate history."

And there is also a graph to go along with the above definition, in case you were still skeptical about the whole "defying THE Sir Isaac Newton thing":



[Nope you can't walk on water] <----- go to the link if you care enough.

Anyway, enough about the crazy albeit "silly" antics one can pull (no pun intended) with non-Newtonian fluids. Let's talk dirty (I mean, chemistry.) [More wikipedia] The polymers in silly putty have covalent bonds within the molecules, but hydrogen bonds between the molecules. The hydrogen bonds are easily broken. When small amounts of stress are slowly applied to the putty, only a few bonds are broken and the putty "flows". When larger amounts of stress are applied quickly, there are many hydrogen bonds that break, causing the putty to break or tear. (gosh, I hate chem but thanks to George Facer I at least have a working knowledge of this god-awful subject)

Hence, if a 50 pound spherical mass of silly putty was to be dropped from a tall building (just for kicks, say it was dropped from the leaning tower of Pisa), it would shatter on impact with the ground. This is because it is a non-newtonian fliud or is viscoelastic. Which means that if handled slowly it acts like a liquid, but if handled at high speeds or vigorously, it acts like a solid. So when it hit the ground it was basically a solid ball of plastic and shattered.

To FURTHER explain non-Newtonian fluids, lets talk about sauce [baby, let talk about you and me....i'm sorry but I was watching Pitch Perfect]. You must've experienced the frustration of not being able to pour the right amount of ketchup out of the bottle. Either nothing comes out, or the pacific ocean just landed on your plate. This is actually due to the viscosity of ketchup, which can be affected by how much force you apply to the ketchup bottle or by how long you have been trying to get something to come out of it.

What does any of this have to do with Comparative Planetology? The subject was brought up because rocks and other materials that make up objects in our Solar System have a viscous flow over geologic time scales (fancy word for historic timeline). More specifically, formations on planet surfaces, such as craters or mountains, have a relaxation time, just as silly putty will relax and deform from a vertical position to a flatter one. Comparing different craters shows us some are more defined than others, causing scientists to theorize viscous interiors for observed objects, just as the Earth’s mantle is a viscous layer.
 

For example, researchers have noticed significant differences between craters on the Moon and craters on Ganymede (picture 1), one of Jupiter’s moons. The Moon’s craters (picture 2) are very clear and well-defined; there’s hardly any visible relaxation. Ganymede, on the other hand, has craters that are flattened. Notice in the image below of Ganymede: several of the more recent craters are deep and well-defined, but the others in the surrounding area appear faded. Something had to make those craters deform like this, and viscous flow is go-to theory for geologists. Composition is also suspected to play a big part in it, considering Ganymede is an icy satellite while the Moon is just a lump of rock. Ice relaxes much faster than rock, confirmed by these observations.

                     

So there you have it. Silly putty and ketchup helped us learn about the behavior of materials, which have been used to help us observe our Solar System. By observing other objects, we hope to eventually figure out the best theory for our own planet’s formation, which we actually do not know as much about as people would think!

(I am seriously contemplating majoring in astrophysics now, though studying engineering alongside will make that almost impossible.)


P.S: Original title was going to be 'What do silly putty and mustard sauce have in common' but I'm not much of a fan of mustard sauce.

P.P.S: Douglas Adams broached this topic in his book The hitchhiker's guide to the galaxy, in a poem entitled "Ode to a Small Lump of Green Putty I Found in My Armpit One Midsummer Morning."

P.P.P.S: Congratulations to you if you managed to make it to the end of this post.