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"Neat" Pictures


Dr. Anomaly

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Re: "Neat" Pictures

 

And isn't that an odd coincidence.

 

Lucius Alexander

 

The palindromedary suspects the odds are....astronomical

 

Actually, I would have to look at someone else's numbers.

 

IF you have a planet with a moon that's a substantial fraction of the planet's size (Moon is 1/80 of Earth's mass; its density is lower by roughly 40%),

 

AND if that moon starts out close to the planet when both are formed,

 

THEN the moon's orbit will get larger over geological time, due to tidal friction and dynamical coupling between the planet's rotation and the moon's orbit.

 

That in turn will mean the moon's angular size will start big and diminish over time.

 

AND, the bigger the moon, the stronger the tides, and the faster the tidal braking and orbit modification start out being.

 

SO if the planet-moon system is not too close to the star, then, it is sort of inevitable that the moon will start with an angular size larger than the star's as seen from the planet.

 

I think the orbit size increase (and therefore angular size decrease of the moon) is an exponential decay, that is, the fractional rate of change drops with time. Even if it starts out large, it'll decay to a fairly modest rate once the moon is far enough out.

 

So while the near-perfect coincidence of equal angular sizes of Sun and Moon is a remarkable coincidence, comparable values for those angular sizes may be inevitable, given (1) a large moon, (2) a planet with orbit on the ~1 AU scale (as opposed to the <0.1AU scale), and (3) it takes a few billion years creatures to evolve on the planet that have the capacity to scratch their heads over coincidences in apparent celestial phenomena.

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Re: "Neat" Pictures

 

The artist behind Dresden Codak noted the DC reboot by redoing the characters himself, villains and heroes alike.

 

I'll only post a couple, in the interest of brevity, but some of these are really good. If you follow the links, do read the modified backstories.

 

tumblr_lsh6d7296X1qc9wc7.jpg

 

tumblr_lsh6efllE41qc9wc7.jpg

(note, that isn't an absence of color. This wonder woman is made of living marble)

 

tumblr_lsqjpdvFIL1qc9wc7.jpg

 

tumblr_lsqihdIAft1qc9wc7.jpg

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