Posted on 09/10/2015 4:53:58 PM PDT by BenLurkin
“Seeing dunes on Pluto — if that is what they are — would be completely wild, because Pluto’s atmosphere today is so thin,” said William B. McKinnon, a GGI deputy lead from Washington University, St. Louis. “Either Pluto had a thicker atmosphere in the past, or some process we haven’t figured out is at work. It’s a head-scratcher.”
Plus, a new view of Pluto’s hazy backlit atmosphere shows what are likely crepuscular rays — shadows cast on the haze by topography such as mountain ranges on Pluto, similar to the rays sometimes seen in the sky after the sun sets behind mountains on Earth.
Scientists say these new images reveal that Pluto’s global atmospheric haze has many more layers than scientists realized, and that the haze actually creates a twilight effect that softly illuminates nightside terrain near sunset, making them visible to the cameras aboard New Horizons.
“This bonus twilight view is a wonderful gift that Pluto has handed to us,” said John Spencer, a GGI deputy lead from SwRI. “Now we can study geology in terrain that we never expected to see.”
(Excerpt) Read more at universetoday.com ...
Interesting. Thanks!
Well, they can’t say, “stunning”, “breathtaking” or “spectacular” in every headline....
What did I see this morning in the East before sunrise? Crescent Moon with Venus or Jupiter beneath it. Do you know which?
Breathtaking! Hoping to catch that tomorrow morning, too, if the clouds move out. :)
We live in the COOLEST Solar System EVER! :)
You’re welcome. All of that was from the included link.
As an undergrad I studied a fair bit of geomorphology. As far as sand is concerned, this is the Bible: http://www.amazon.com/Physics-Blown-Desert-Dunes-Science/dp/0486439313
The disk of the sun would subtend an angle of about 0.014 degrees. The moon subtends an angle of about 0.57 degree. So the sun width would appear to be 1/40th the width of our moon. A lot brighter, but still nearly a pinpoint of light.
Thanks. I very nearly completed a BS undergrad degree in geology. Long sad story. :)
Must have been Venus. If it was a clear dark morning sky, and the two were side by side, there would be no mistaking Jupiter for Venus. Venus is much brighter.
"Catch the waning Moon, Venus and Mars in early dawn..."
Source: Sky & Telescope Magazine:
http://www.skyandtelescope.com/observing/sky-at-a-glance/this-weeks-sky-at-a-glance-september-4-12/
You know when we see all these planets up close as this...and then see our earth...it’s stunning to see all the “life” we have here...stunning!
Wouldn’t the creation of sand itself require some complex erosional processes?
Absolutely. Great point. Makes things there even more puzzling and bizarre.
“Sand is a sedimentary material; loose grains of worn out and disintegrated rocks.
Sand is of fine granules with grains ranging between 0.06 and 2.0 mm in diameter.
Sand is a naturally occurring fragmented material comprised of tiny particles of decomposed rocks, shells, or corals.
So how does sand come about?
The most common natural process of sand formation is called weathering. Majority of sand comes from chemical and mechanical breakdown (weathering) of bedrocks. Such process can take hundreds or even millions of years depending on other mechanical processes such as temperature changes, wedging by plant roots or salt crystals, and ice gouging underneath glaciers. A waterfall continuously pounding on a huge rock would cause little bits and pieces of the rock to be detached.
Formation and composition of sand depends largely on the source material. Sand that is found on the beach are mostly composed of quartz which is the most common material found in sand, or possibly some amounts of feldspar which is more prone to chemical breakdown, and other commonly occurring materials in the general beach vicinity coming from igneous rocks nearby.
On the other hand, sand around volcanic islands is commonly composed of volcanic rock decomposed fragments and other minerals coming from volcanic rocks such as volcanic glass.
In areas where there isn’t much of sedimentary material from mountains or volcanoes, sand is commonly composed of organic material that have decayed and fragmented such as corals, shells, and skeletons of little planktonic organisms.
Quartz has a high resistance to chemical and mechanical weathering and it is also one of the most commonly naturally occurring mineral on Earth. Plenty of types of sand consist largely of quartz. Other types of sand consist of feldspar, fragments of igneous, and fragments of metamorphic rocks. Hydrodynamic or chemical precipitation processes can produce sand that consists mostly of glauconite, calcite, or dense and dark-colored minerals like magnetite and ilmenite.”
http://www.tech-faq.com/how-sand-is-formed.html
Thanks BenLurkin, extra to APoD.
Great Stuff, Ben Lurkin!( Where have you been lurking?)
And I think that inconceivable guy from “the Princess Bride” has gone on to his next life. Thanks again, BIN LURKIN. It almost sounds like an Arab name BIN LADEN, BIN LURKIN...
You can call me Ben.
What a great site. Thanks for posting.
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