I’m fascinated by geology, especially when seen from above. Pictures from the Mars Reconnaissance Orbiter are a favorite, and I particularly like images of gullies in crater walls; something is flowing down them, though it’s not known just what. It could be water that flash melts for some reasons, but it could also be a form of carbon dioxide clathrates, which are still quite interesting but lack the oomph that water elicits in us.
Anyway, here is a shot I quite like that was just taken, showing tributaries flowing down hill, joining up to make dozens of main stems flowing along:
If you just glance at that picture, you might be forgiven for thinking it’s also from Mars, or perhaps a satellite high above the Earth. The shapes and relative sizes of the tributaries look about right.
But here’s a second shot that should give you more of a sense of scale.
Surprise! Canis Minor is a multipurpose companion.
So yeah, I took these shots myself when my wife and I were out walking the dogs. We had a decent amount of rain the other day, and it drained off the street into the shallow gutter. The water carried sediment, which piled up along the gutter; you can see it on the bottom of the shot.
I love how scale works in nature. A drop of water in space forms a sphere due to surface tension, while a mighty elliptical galaxy 100,000 light year across might also form a sphere due to the mutual gravity of its hundreds of billions of stars. Spirals swirl in your coffee cup, and in galaxies as well (though for very different reasons). And little runlets of water flow, meet up, and create patterns very much like those hundreds of meters of even kilometers across, not just on Earth but on other planets as well.
Fantastic! The nature of Nature never ceases to draw wonder from me, with its incredible complexity in detail yet miserly attitude toward gross configurations over huge scales. It’s amazing what’s out there, if you just notice it.