Starship Asterisk*

by **pferkul** » Thu Jan 19, 2023 12:20 am

johnnydeep wrote: ↑Tue Jan 17, 2023 2:26 pm
Wikipedia says it's 1.5 km high - https://en.wikipedia.org/wiki/Mons_La_Hire

I don't know. What can we deduce from a close-up of the Google Moon map showing a shadow an a 10 mi scale:

Guess we can conclude that a 1-mile-high mountain casting a shadow 100 miles long would need the sun to be only 0.6 degree above the horizon.

tan^-1(1/100) = 0.6 deg.

In the original APOD image, it looks like the mountain is far enough from the terminator that the sun would be substantially higher than 0.6 deg. I guess looks can be deceiving in the twilight zone!

by **johnnydeep** » Wed Jan 18, 2023 2:53 pm

pferkul wrote: ↑Wed Jan 18, 2023 12:13 am
johnnydeep wrote: ↑Tue Jan 17, 2023 2:26 pm
Wikipedia says it's 1.5 km high - https://en.wikipedia.org/wiki/Mons_La_Hire

So your height calculation seems to be off. I'll let others figure out why.
I know my height can't be correct, that's what I was asking. To put it another way, why does the shadow of the 1.5 km mountain appears to be 80 km long, when the sun is only about 10 degrees above the horizon? Attached is a scaled image from MOONTrek. The sun must be closer to only 1 degree above the horizon.

I don't know. What can we deduce from a close-up of the Google Moon map showing a shadow an a 10 mi scale:

by **pferkul** » Wed Jan 18, 2023 12:13 am

johnnydeep wrote: ↑Tue Jan 17, 2023 2:26 pm
Wikipedia says it's 1.5 km high - https://en.wikipedia.org/wiki/Mons_La_Hire

So your height calculation seems to be off. I'll let others figure out why.

I know my height can't be correct, that's what I was asking. To put it another way, why does the shadow of the 1.5 km mountain appears to be 80 km long, when the sun is only about 10 degrees above the horizon? Attached is a scaled image from MOONTrek. The sun must be closer to only 1 degree above the horizon.

by **johnnydeep** » Tue Jan 17, 2023 2:26 pm

pferkul wrote: ↑Mon Jan 16, 2023 11:34 pm There is a feature on the upper left near the terminator that casts a shadow of around 40 miles (if my estimate is correct). Based on its distance from the terminator, the sun is about 10 degrees above the horizon, meaning the feature's height is about (40 miles) x tan (10 deg) = 7 miles. What am I missing?

Apparently, not much! That's Mons La Hire near Lambert crater - https://www.google.com/maps/space/moon/ ... a=!3m1!1e3

Wikipedia says it's 1.5 km high - https://en.wikipedia.org/wiki/Mons_La_Hire

So your height calculation seems to be off. I'll let others figure out why.

by **pferkul** » Mon Jan 16, 2023 11:34 pm

There is a feature on the upper left near the terminator that casts a shadow of around 40 miles (if my estimate is correct). Based on its distance from the terminator, the sun is about 10 degrees above the horizon, meaning the feature's height is about (40 miles) x tan (10 deg) = 7 miles. What am I missing?

by **Chris Peterson** » Mon Jan 16, 2023 3:48 pm

De58te wrote: ↑Mon Jan 16, 2023 12:43 pm If I may conjecture about why the blue iron rich areas are not spread out evenly but mostly found gathered where the maria and oceans are. The theory goes that the Moon was formed early on when a Mars sized object crashed into the young Earth. Most of the Earth's light outer layers were blasted into an orbiting cloud which then coalesced into the Moon. So where did the iron come from on the Moon? I think that the later meteors that crashed into the areas that carved out the Marias were large and possibly iron rich meteors, and that iron didn't originate from the Earth. What do you think? Excuse me if that already is in the science database.

I believe the general view is that surface iron on the Moon comes from basaltic deposition. That is, the iron is present in magma which flows onto the surface. Several recent measurements also suggest that the concentration increases with depth, which is considered supportive of the model where the Moon formed from a giant impact on Earth and the subsequent consolidation of crustal and mantle debris (which is high in iron).

by **johnnydeep** » Mon Jan 16, 2023 3:46 pm

Yes, very impressive work indeed, Darya! From the link to the Instagram page:

daryavaseum
Proudly representing my most detailed moon image i ever photographed.

I took almost a quarter million frames (231,000) and i spend unimaginable amount of work over the course of 3 weeks to process and stack all the data which was equivalent to 313 GB.

I used the most basic astronomical camera (ZWO ASI120mc along with my 8 inch telescope (celestron nextsar 8se) without a barlow i.e at prime focus 2032 mm.

The mosaic moon was compromised with 77 panels each panel consist of 3000 frames. It is worth mentioning that i used canon eos 1200D to add mineral color on the surface.

by **orin stepanek** » Mon Jan 16, 2023 3:25 pm

It may not be how Luna really looks; but it shows the
sharpness of the surface! I like it!

by **Ann** » Mon Jan 16, 2023 1:20 pm

De58te wrote: ↑Mon Jan 16, 2023 12:43 pm If I may conjecture about why the blue iron rich areas are not spread out evenly but mostly found gathered where the maria and oceans are. The theory goes that the Moon was formed early on when a Mars sized object crashed into the young Earth. Most of the Earth's light outer layers were blasted into an orbiting cloud which then coalesced into the Moon. So where did the iron come from on the Moon? I think that the later meteors that crashed into the areas that carved out the Marias were large and possibly iron rich meteors, and that iron didn't originate from the Earth. What do you think? Excuse me if that already is in the science database.

Sounds like a good explanation to me.

Ann

by **De58te** » Mon Jan 16, 2023 12:43 pm

If I may conjecture about why the blue iron rich areas are not spread out evenly but mostly found gathered where the maria and oceans are. The theory goes that the Moon was formed early on when a Mars sized object crashed into the young Earth. Most of the Earth's light outer layers were blasted into an orbiting cloud which then coalesced into the Moon. So where did the iron come from on the Moon? I think that the later meteors that crashed into the areas that carved out the Marias were large and possibly iron rich meteors, and that iron didn't originate from the Earth. What do you think? Excuse me if that already is in the science database.

by **MarkBour** » Mon Jan 16, 2023 6:57 am

Incredible rendering, Darya! 231,000 frames, sounds like a vast amount of work.

A reaction to looking at some of the minerals on the Moon:
I realize we are increasingly looking at Luna with that human lust and industry. What have we found thus far, I wonder, that could be helpful in terms of building materials, resources for possible water, fuel, agriculture, and as one extreme, mining for return to Earth?

Although the Moon looks pretty plain and dead, and it may always be that it will never be commercially advantageous to claim rights to anything there, I think the UN will want to plan ahead and prevent any nastiness that they can. Both as we return to the Moon and as we consider other celestial bodies.

by **APOD Robot** » Mon Jan 16, 2023 5:05 am

Moon Enhanced

Explanation: Our Moon doesn't really look like this. Earth's Moon, Luna, doesn't naturally show this rich texture, and its colors are more subtle. But this digital creation is based on reality. The featured image is a composite of multiple images and enhanced to bring up real surface features. The enhancements, for example, show more clearly craters that illustrate the tremendous bombardment our Moon has been through during its 4.6-billion-year history. The dark areas, called maria, have fewer craters and were once seas of molten lava. Additionally, the image colors, although based on the moon's real composition, are changed and exaggerated. Here, a blue hue indicates a region that is iron rich, while orange indicates a slight excess of aluminum. Although the Moon has shown the same side to the Earth for billions of years, modern technology is allowing humanity to learn much more about it -- and how it affects the Earth.

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