Crazy unearthly planetary phenomena described


Originally published at:


But do any of those planets have little bits of it that are animate and self aware?


would that be a “feature” (or a bug?)


wind that’s 29 times faster than sound


Are they describing wind that’s 29 times faster than the speed of sound through air, on Earth? Or is it wind that’s 29 times faster than the speed of sound on that planet?

I can see the former being possible; the latter seems unsustainable.


Both. Heck, we have it here in the Solar System; Neptune winds have been clocked at 1,300 mph, in excess of the local speed of sound.


We have Chipotle, so it’s only a matter of time.


… I don’t get how that works.

Wind is air moving to equalize a pressure differential.

Sound waves are variations in air pressure.

I can understand how wind can, for a brief time, be enticed to go faster than the speed of sound (for instance, immediately behind a sufficiently powerful jet engine). However, on an ongoing basis, how can a variation in pressure equalize faster than the pressure wave can itself travel?


Massive temperature differentials–on the order of hundreds of degrees C. In the example given in the linked video, there’s a gas giant (HD 209458 b, informally known as Osiris) which is orbiting a sun-like star in a 3.5 day orbit. The side facing the star is being cooked to a nice 1000 C on that side, which is causing hypersonic winds blowing away from the subsolar point and to the comparatively cooler (“only” 600 C) dark side. These winds have been directly measured by astronomers as clocking as high as 10,000 km/h, significantly faster than the local speed of sound.


Ah. That makes sense. I was thinking they were describing a massive storm, like on a gas giant. But a situation where that much thermal energy is being injected at close range directly from the sun, I can see that injecting enough energy to make the wind break the sound barrier.

Not to mention that, at that range, the solar wind is probably actually physically blowing the atmosphere to the far side of the planet enough for that to make a measurable change to the wind speed.


We’ve actually detected exo-planets where the atmosphere is being blown off of the planet by the star in measurable quantities.

Edited to exo-planets because of pedants.


The Doppler shift would sound crazy but as soon as any sources create a compression wave in that medium it must be travelling faster than the medium (relative to some frame of reference) in order to be described as propagating through it (with any speed).

If the speed of sound is a function of the density and movement of the medium that the compression waves travel through, then In a sense, the article is describing the wind as being faster than itself.

Ah, I see you got there already :smile:

Also, I’m playing my one time Get-out-of-chaotically-turbulent-air-jail card b4 ppl are all like “Propagation!!?”


Not that we had to look too far.


NASA is so awesome.

Will somebody please give them a couple trillion bucks and a fucking crazy mandate?


That’s solar wind stripping; here, I’m talking about the planet being so hot via direct heating that the atmosphere is being blown off in a visible tail.

Which, by the way, the prime suspect is Osiris (again):

Gliese 436 b is also a possibility–it looks like there’s no hydrogen left on the planet at this point due to the same effect.


My biggest take away from this video is we need better names for exoplanets.



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