Dark Side of the Pluto


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Physics pedantry: Nearly spherical droplets result in rainbows, like prisms do. Here’s a rough diagram of the correct geometry.


Yes, but this isn’t a case of droplets in Pluto’s atmosphere; it is refraction in the atmosphere itself. Because the atmosphere fades into space, there isn’t a hard boundary to deflect incoming light, but as light travels through the atmosphere it encounters a varying refractive index causing a slight bending of a ray that would nearly graze the surface. So the post may be approximately correct in principle, though whether there is any splitting will depend on the dispersion of the Plutonian atmosphere - and I haven’t the first clue about that.


More pedantry: No, the bright ring is mostly due to forward scattering, not refraction. They are only indirectly related. Sunset colors are mostly a result of scattering (preferential scattering as a function of color), not refraction.


An awesome work of art Xeni.


I’m not thinking people who fondly remember the Floyd care much for such pedantry.


Some do. Me for one.


Now that we know the exact density of Pluto’s atmosphere, I wonder if the next mission could be a lander. Perhaps it could be done with a huge parachute to maximize drag, and the first pass would just get you under escape velocity.

Also, that picture is a terrible mixed metaphor based on a totally wrong original.


I saw a rainbow during sunset the other day. Just a red arc with the other colors very faint. Really cool!


I’ve heard that NASA is covering up the discovery of Plutonian Unicorns that cause light to refract in unexpected ways.


That’s diffraction, due to smaller uniformly sized droplets.


The herds of Plutonian Unicorns align themselves with the prevailing winds thus redirecting light in an uniform direction.


Though it’s not involving the metafractylizationalification of light through a unicorn’s butt (I digress to @crenquis and @MarkDow to work out those details), NPR’s science tumblr built a nice image of New Horizon’s path out to Pluto:


That’s just science…


Dark side of the sun is much more fun


Dark side of the son


surely they care about pedantry relating to the Floyd?


I am aware of that. However, if you look at the original post it showed spectral separation from a beam continuing on roughly the same direction, as happens in a prism. You responded that the separated beam would be back reflected as happens in a rainbow seen on Earth. I was pointing out that the original scenario was at least possible (it would happen in an atmosphere that had significant divergence, but I think it would need to be much, much denser than that of Pluto and offhand I can’t think of any gases with any divergence). Forward scattering doesn’t result in a spectrum, but a loss of the higher frequencies in the beam which get preferentially scattered…


Slingshot maneuvers are cool as fuck . Look at it go! Wheeeee!!!


You win at the Internet for this post.