Highres moon fresh impact crater

[multiweb (Marc)]

http://lroc.sese.asu.edu/posts/1003

Zoomable tiff pic at the bottom of the article.

[JeniSkunk (Jenifur)]

Thanks for the link to this, Marc.
Grabbing the .TIF for examination at my leisure.

[Dennis]

Originally Posted by multiweb

http://lroc.sese.asu.edu/posts/1003

Zoomable tiff pic at the bottom of the article.

Wow Marc, that zoomable tif was just quite breathtaking, such extraordinary detail with so much clarity.

Time to retire my Mewlon from lunar photography methinks...

Cheers

Dennis

[MortonH]

What an awesome image!

[PhilTas (Phil)]

Thanks Marc,
I really enjoy these lunar articles.
The hires image is excellent.
cheers Phil

[silv (Annette)]

breathtaking detail. Thanks for posting the link.

What's also visible in full detail: the centre of the crater is not a mountain like in many others. And the rim and debris dispersion around it are not perfectly round like many other craters' surroundings - but shows that the object impacted at an angle.

So this looks like what I would expect an impact crater to look like. A visible impact angle and no mountain in the middle.

I don't understand the scientific assumption that the centre mountains visible in many other craters got created by some form trampoline-effect: when the debris at the bottom jumps up again and then collects in a uniform centre mountain.

Equally I don't understand why craters look a perfectly round shape without a trace of angled impact in the rim nor in the surrounding area where the fallout debris came down. That rim and debris pattern should look like this: < and not like this: o

What do you guys think?

[Wavytone]

Annette, regarding the impacts at an oblique angle - the clue for these is asymmetry in the way the ejecta are distributed around it, usually most of the material is in the forward direction and very little in the rearward direction.

Also bear in mind the cratering occurred in several phases. Early on the moon still had a semi-molten core so impacts were like hitting a big ball of stiff goo, and the central mountains on crater floors resulted from hydraulic pressure forcing the centre up, since the crater floors were a few hundred metres below the surface. And bear in mind the density of rock is ~ 6X that of water so the forces are immense.

[julianh72 (Julian)]

Here's a link to the same crater on the recently-posted LROC zoomable Moon map:
https://quickmap.lroc.asu.edu/projec...npEoAsjZwLrc0A
(Thanks multiweb!)

The LROC imagery gives a straight-down perspective, so the asymmetry from the oblique impact is even more apparent, but the flat crater floor is less apparent. The LROC imagery seems to go to slightly higher resolution, but the crater is covered by several passes, and the illumination is a bit dark in some parts in the default layers. (I'm not sure if this can be improved by selecting different layers to view.)

These are fantastic resources, enabling lunar exploration from the comfort of your armchair - thanks to the OPs for sharing!

[gary]

Hi Marc,

Thanks for the link.

A jaw dropping photo and an all-round wonderful web site.

I happened across this page where they discuss "Quantifying Crater Shapes" :-
http://lroc.sese.asu.edu/posts/864

Originally Posted by LROC

Among many polynomials, we found the Chebyshev polynomials to be particularly suited to successfully describe crater shapes.

Chebyshev Coefficients

We found that the topography of nearly all lunar craters can be represented by a relatively small set of the Chebyshev polynomials (a subset is shown below). In this representation, the individual polynomial functions are scaled and summed to approximate the actual crater elevation profile. The scaling factors are the Chebyshev coefficients.

The individual Chebyshev functions each represent a component of the overall crater shape (such as, part of the crater rim, wall, or floor) and, combined with the corresponding coefficients, describes a particular crater. Thus only the coefficients change from crater to crater, allowing the creation of a vast and highly precise database of lunar crater shapes!

It reminded me of the character Slartibartfast in Douglas Adams "The Hitchhiker's Guide to the Galaxy".

Slartibartbast is a designer of planets and he is working on the design
for the coastline of Africa for a new Earth after the original was destroyed.

Originally Posted by Slartibartfast

"In this replacement Earth we're building they've given me Africa
to do and of course I'm doing it with all fjords again because I
happen to like them, and I'm old fashioned enough to think that
they give a lovely baroque feel to a continent.

Slartibartfast would probably reach for fractals rather than polynomials.

[multiweb (Marc)]

There's a bunch of line and polygon tools that you can drag and create elevation profiles on the map as well. You need to select the tool, click once then click again to finish the line then again on the end and a graph will popup. That rebound mount in the middle of Tycho is 2000m. We're talking Mount Kosciuszko there. Imagine the energy of the impact to create something that high which is basically just like the little column of water that bounces back when a drop falls on a liquid surface. I reckon you wouldn't want to be on the moon anywhere when that happened.

[JeniSkunk (Jenifur)]

Originally Posted by julianh72

Here's a link to the same crater on the recently-posted LROC zoomable Moon map:

Thanks for the link Julian. Shows how small that crater really is.
No wonder I couldn't see it in my poor little 130mm scope, even with my 6.5mm eyepiece and 2x Barlow, when I tried looking for it this evening.

[gary]

Originally Posted by University of Toronto, Jan 17 2019

An international team of scientists is challenging our understanding of a part of Earth’s history by looking at the moon, the most complete and accessible chronicle of the asteroid collisions that carved our solar system.

In a study published today in Science, the team shows the number of asteroid impacts on the moon and Earth increased by two to three times starting around 290 million years ago.

“Our research provides evidence for a dramatic change in the rate of asteroid impacts on both Earth and the moon that occurred around the end of the Paleozoic era,” said lead author Sara Mazrouei, who recently earned her PhD in the department of Earth sciences in the University of Toronto’s Faculty of Arts & Science.

“The implication is that since that time we have been in a period of relatively high rate of asteroid impacts that is 2.6 times higher than it was prior to 290 million years ago.”

It had previously been assumed that most asteroid-produced craters on the Earth older than 290 million years had been erased by erosion and other geologic processes. But the new research shows otherwise.

“The relative rarity of large craters on Earth older than 290 million years and younger than 650 million years is not because we lost the craters, but because the impact rate during that time was lower than it is now,” said Rebecca Ghent, an associate professor in U of T’s department of Earth sciences and one of the paper’s co-authors. “We expect this to be of interest to anyone interested in the impact history of both Earth and the moon, and the role that it might have played in the history of life on Earth.”

Scientists have for decades tried to understand the rate that asteroids hit Earth by using radiometric dating of the rocks around craters to determine their ages. But because it was believed erosion caused some craters to disappear, it was difficult to find an accurate impact rate and determine whether it had changed over time.

A way to sidestep this problem is to examine the moon, which is hit by asteroids in the same proportions over time as Earth. But there was no way to determine the ages of lunar craters until NASA’s Lunar Reconnaissance Orbiter (LRO) started circling the moon a decade ago and studying its surface.

“The LRO’s instruments have allowed scientists to peer back in time at the forces that shaped the moon,” said Noah Petro, an LRO project scientist based at NASA Goddard Space Flight Center.

Using LRO data, the team was able to assemble a list of the ages of all lunar craters younger than about a billion years. They did this by using data from LRO’s Diviner instrument, a radiometer that measures the heat radiating from the moon’s surface, to monitor the rate of degradation of young craters.

During the lunar night, rocks radiate much more heat than fine-grained soil called regolith. This allows scientists to distinguish rocks from fine particles in thermal images. Ghent had previously used this information to calculate the rate at which large rocks around the moon’s young craters – ejected onto the surface during asteroid impact – break down into soil over tens of millions of years. By applying this idea, the team was able to calculate ages for previously undated lunar craters.

When compared to a similar timeline of Earth’s craters, they found the two bodies had recorded the same history of asteroid bombardment.

Full press release here :-

https://www.utoronto.ca/news/team-sc...-studying-moon

[silv (Annette)]

That's interesting, Gary.
290 Mio years ago something upset the belts, Jovian, Kuiper or Oort, and sent stuff flying towards moon and earth.

Could have been a wandering body like Gliese 710 which is coming towards the solar system and will upset the assumed Oort cloud in about 1.2 Mio years.

Theoretically, if you had a more capable computer than I do, one could use GaiaSky to find out which body, if any, touched our system 290 Mio years ago.
GaiaSky is a 3D visualisation program incorporating the Gaia Data release 2. Runs on Wind, Linx, Mac.

To see what Gliese 710 is up to, I let GaiaSky "run" into the future on my Mac. But the computation of so much data didn't complete; my Mac being too weak - or maybe I just didn't give it enough time to catch up with things?