Lunar craters, young and old

By Phil Plait | April 8, 2011 10:00 am

This is a pretty neat picture taken by the Lunar Reconnaissance Orbiter: two craters, side by side:

[Click to impactenate.]

What’s cool about it is the obvious age discrepancy between the two craters. The Moon lacks water and air, but it has erosion nonetheless: micrometeorite impacts, solar wind, and even thermal stress cause by the month-long day night cycle slowly wears away at the surface. Old craters have a rounded look to them, while fresher craters are sharp-edged, and show the debris from impact.

The full-res image has a scale of just a meter per pixel, so a lot of the smaller boulders you see around the younger crater on the right are the size of cars. Both craters are roughly 300 or so meters across; you could walk briskly across them in a couple of minutes.

I noticed the young crater has an odd shape, non-circular, almost diamond-shaped. Then I looked at other, nearby craters, and saw the same thing, so it must mostly be due to lighting. However, there is a funny hillock just to the right of the crater, and the boulder field around it is not symmetric; there are more above and below it. I wonder if there is a density change in the underlying rock just to the right of the crater, which helped shape the crater…?

That area is mostly flat lava flood plains, and in the zoomable and pannable larger-area context image there are some interesting features that look like very old crater rims poking up through the plain. Check it out! One of my favorite things about LRO is the pile of high-res pictures like this one you can zoom in an out of. It really helps give you a feel for what you’re seeing.



[Below is a gallery from some of my favorite pictures from LRO.]


Comments (20)

  1. dave cortesi

    Phil, how about a shout-out to Moon Zoo (http://www.moonzoo.org/) where anybody can join in to help classify and measure thousands of craters like this one? Moon Zoo is crowd-sourcing a complete atlas of craters from LRO pics.

  2. Craig

    Hey Bad Astronomer, I enjoy reading your blog, but your RSS feed always cuts off partway through the article. For example, this post cuts off at “However, there is a funny hillock just to the right of the crater, and the boulder field around it is not symmetric; there are …” Is there any chance you could have this fixed?

  3. mike burkhart

    These are good photos,The fact that we find craters on other planets,moons and asteroids and even Earth shows objects in the early Solar System were bombarded by an artillery brage the likes of witch we’ve never seen . Nature can be more destructive then man.

  4. andy

    Looks like you’ve got an unclosed tag in there…

  5. Quiet Desperation

    Adding italic close tags.

  6. Keith Bowden

    Please, Phil, have a little consideration for the health of our down-under friend, Messier Tidy Upper. All these moon photos and comments about going back are just going to get his blood pressure up! ;)

    Seriously, these are great photos and I long for the day one can commute between domes along that natural bridge. Then again, considering the bridge tolls here in the Bay Area, maybe not… (Okay, being serious didn’t last long…)

  7. Just a short note to say i ~love~ your made-up verbs like “impactenate”

    You do it regularly, and the results are invariably pleasing.

    Wish I could remember the really good ones, because you’ve created some doozies.

    Please, keep up the good work.

  8. Tim G

    “Both craters are roughly 300 or so meters across; you could walk briskly across them in a couple of minutes.”

    I think it would be easier in one-sixth gravity to hop, skip and jump across them.

  9. Thameron

    Anybody else see the Cookie Monster in that picture? Damn pareidolia.

  10. Michael Swanson

    I can’t help but think of the silliness of creationist hokum when I see images like this. God creates a perfect world and puts a Moon in the sky to help us find our way at night (for most of the month anyway) or for us to just appreciate its beauty. Oh, and he throws about a trillion rocks into wild orbits around the Sun so that they can occasionally smash the bejesus out of it! What kind of weird behavior would THAT be if it was designed? Of course, it makes perfect sense for objects to hit the Earth, since we’re wicked and all, but what did the Moon ever do?

  11. Thameron

    @9. Michael Swanson

    “but what did the Moon ever do?”

    Maybe it, uh, mooned him?

  12. Procyan

    That is a facinating image. It is easy to spend some time getting the “feel” of the blast that created that rubble field.

    BTW/ This reminds me of a question I have had for many years about rays in general…for example Tycho and most recently in some Messenger images, some rays don’t quite trace back to the crater of origin properly. The alignment of some are just not right, offset and even parallel to an adjacent ray instead of converging at the crater. Have others noticed this? How could that happen? In fact, how do rays form anyway…instead of just a uniform debris field?

  13. mike burkhart

    Michael Swanson #10 The creationsts miss the point of that chapter . The point is not that the Sun and Moon were created on the thrid day but that they are just lights and not Gods . To understand what I’m talking about you have to know that in the age the Bible was writen all of the neighbors of acient Isreal worshiped the Sun and Moon as Gods , and the Hebrews were slaves in Egypt for 400 years the cheif God in Egypt was the Sun God Ammon-Ra . So this writen to prevent idolitory.

  14. Robbie

    @ Thameron: I lol’d.

  15. Messier Tidy Upper

    Neat crater images. :-)

    [Pedant mode]

    The Moon lacks water and air,

    Technically speaking the Moon doesn’t entirely lack air :

    http://en.wikipedia.org/wiki/Atmosphere_of_the_Moon

    There’s just *very*, precious little of it! ;-) [/pedant mode off.]

    The Moon apparently (if Wikipedia can be trusted) has more “air” (atmosphere) than Mercury and our Luna also boasts a sodium tail too.

    Of course, for practical purposes its pretty much vacuum but still. ;-)

  16. Messier Tidy Upper

    @6. Keith Bowden : Thanks for your concern, I think I’m alright … ;-)

    @12. Procyan :

    This reminds me of a question I have had for many years about rays in general…for example Tycho and most recently in some Messenger images, some rays don’t quite trace back to the crater of origin properly. The alignment of some are just not right, offset and even parallel to an adjacent ray instead of converging at the crater. Have others noticed this? How could that happen? In fact, how do rays form anyway…instead of just a uniform debris field?

    My guess would be that it might have something to do with the angle of impact that the meteorite that struck had perhaps? I’m not really sure of this however.

    Another possibility is that the crater rays are actually coming from different craters ie. not the one that it may first seem to be but another smaller crater inside that one?

    One suggestion is that you can actually simulate crater formation using – among other things – a tray of flour covered 2 cm deep and smoothed off with more flour dropped onto that tray from varying heights.

    (Source : Pages 18-19The Young Scientist Book of Stars & Planets, Christopher Maynard, Usborne publishing, 1977.)

    @13. mike burkhart :

    Michael Swanson #10 The creationsts miss the point of that chapter . The point is not that the Sun and Moon were created on the thrid day but that they are just lights and not Gods . To understand what I’m talking about you have to know that in the age the Bible was writen all of the neighbors of acient Isreal worshiped the Sun and Moon as Gods , and the Hebrews were slaves in Egypt for 400 years the cheif God in Egypt was the Sun God Ammon-Ra . So this writen to prevent idolitory.

    Well, it wouldn’t be the first time the Creationists have missed the point would it? ;-)

    Seriously, that’s a good point and that – for the times – more rational and less religious anti-idolatry explanation makes sense in that context, although no longer so much in today’s culture.

    Incidentally, I gather the Muslim God “Allah” was originally a Moon god in the pre-Islamic Arab polytheistic culture. Also the Kaaba at the centre of Mecca is a meteorite formerly -and still – worshipped as divine by the tribespeople. (Carl Sagan suggested in one non-fiction book* that the Kaaba might be a fragment from the main-belt asteroid Kalliope.)

    Hmm.. perhaps things haven’t changed that much since the Israelites time after all! ;-)

    ——————-

    * Carl Sagan, ‘Broca’s Brain’, Coronet Books, 1980. “Kalliope and the Kaaba” is the title for chapter 16.

  17. Messier Tidy Upper

    Incidentally, I gather the Muslim God “Allah” was originally a Moon god in the pre-Islamic Arab polytheistic culture.

    In fairness, a quick web search seems to indicate that this is a contentious claim strongly put by some Christian groups and strongly rejected (natch) by Muslims but there does seem to be some evidence for it.

    WARNING : MUSLIM READERS if there are any here MAY FIND THE LINKED MATERIAL HERE UPSETTING

    If so you have been warned – & please allow others their freedom of speech and respond with reasoned civilised argument rather than with violence or nastiness. A cartoon or harsh criticism of beliefs does NOT ever warrant jihads and fatwahs and book burnings.

    One widely dispersed source for this can be found here – albeit this link is to a “Chick tract” religious propaganda site so have some brain bleach handy :

    http://www.chick.com/reading/tracts/1104/1104_01.asp

    Arguing a case that Allah was originally a pagan moon god who married the sun goddess and had daughters – just one of 360 “gods” worshipped origianlly in the kaaba(h?)*.

    A more scholarly and better sourced but still (Christian) religious source for more on this is :

    http://www.biblebelievers.org.au/islam.htm

    Wikipedia has this on asteroid Kalliope :

    http://en.wikipedia.org/wiki/Kalliope_(asteroid)

    Although, it doesn’t mention the idea Sagan suggested that it is the possible origin of the Kaaba stone in Mecca.

    * Wish the Muslims would get the spellings consistent, eg. Kabaa / Kaabah, Quran / Koran, Moslem / Muslim, etc ..? Can’t they – or we – just pick one spelling and stick to it?

  18. scribbler

    (doing best Bohr impression) Who are you to tell God what He can do with His rocks?
    ;-)

    The moon is a Christ Analog, reflecting the light of the sun as the flesh of Christ Reflects the Light of God. How much more appropriate that the surface is beaten to a pulp “protecting” the Earth.

    “Allah” comes from “HaYah/I Am”…

    For the record, Sagan was a fair scientist but a horrid theologian…
    ;-)

    As for the apparent age of things God Creates, think of the water Jesus is reported to have changed to wine. One second there was water and the next those who carried the water in drew out wine. If this wine was examined in even a modern lab, the results of any question of age would certainly not arrive at a few seconds but would conclude that the grapes had to have been grown and aged, it being “good” wine. This proves that those who wrote the bible are “cool” with the idea that men will come to wrong conclusions about the apparent age of God’s Creations…

    A scarecrow in a tuxedo is still a straw man…
    ;-)

  19. Jockaira

    mike burkhart Says: “…the Hebrews were slaves in Egypt for 400 years”

    Mike, I can’t find that anywhere in my Egyptian histories, can you point me in the right direction for verification?…and please, anywhere but the Bible. Thanks in advance.

  20. Messier Tidy Upper

    @ ^ Jockaira : How about you try the Torah then and the Dead Sea Scrolls?
    Or ask any good Rabbi! ;-)

    Incidentally, why *shouldn’t* people trust these ancient writings when they have been supported by considerable archaeological evidence such as specific gates (eg. Gezer, Hazor & Meggiddo) and other structures carbon dated to the right period?

    The Hittite civilisation which was originally known only through the Torah (OT) and later confirmed by archaeologists is another example.

    @18. Scribbler : “Allah” comes from “HaYah/I Am”…

    Er .. How?? That’s nothing like the word “Allah” at all. Citation please?

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