<p>Further imagery has confirmed billion year old surface with impact craters on one part and younger which is very recent and smooth on another part.</p>

<p>Jeff Moore, of the New Horizons team has said. “We now know Pluto has some surfaces that are a billion years old,” </p>

<p>Edit... new estimate quote from NASA:
Based on the lack of impact craters, scientists suspect the surface of Pluto is less than a few hundred million years old, 
Read more at <a href="https://web.archive.org/web/20150807092534/http://newsdaily.com/2015/07/nasa-spacecraft-shows-pluto-wrapped-in-haze-ice-flows/" rel="nofollow noreferrer">http://newsdaily.com/2015/07/nasa-spacecraft-shows-pluto-wrapped-in-haze-ice-flows/#ytDT3emJZSKRbL7b.99</a></p>

<p>He expects that the bulk of the data that he wants to study wont have been beamed back before early 2016.
Large scale image:</p>

<p><a href="https://i.sstatic.net/u6bGY.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/u6bGY.png" alt="http://pluto.jhuapl.edu/images/featuredImages/nh-pluto-mountain-range.png"></a>
<a href="https://i.sstatic.net/6GZb8.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/6GZb8.jpg" alt="boundary of old and new, old dateable by number of craters"></a>
<a href="https://i.sstatic.net/WH6AI.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/WH6AI.jpg" alt="recent zone similar to a convection surface"></a></p>

CC BY-SA 3.0
2015-07-22T11:57:07.333Z
This answer could really use some support for its claim. Such as the referenced image or the source for the claims of billion year old and relatively young surfaces.
Mitch Goshorn
CC BY-SA 3.0
2015-07-22T17:52:00.740Z
@ufomorace Better (good enough for me to give it +1, anyway), but do you have a link to the article or whatever it was that gave the Moore quote?
zibadawa timmy
CC BY-SA 3.0
2015-07-23T11:18:08.363Z
Hi sorry i thought that the phrase would be in search engines... here: http://fortune.com/2015/07/15/nasa-pluto-data-earth/
bandybabboon
CC BY-SA 3.0
2015-07-23T11:31:27.953Z
Moore is a planetary geologist from Nasa, i don't know if he said that the surface is so old because he measured the craters or because of the black surface, will be cool to have further information. Given the size of pluto and the fact that it is ice, an impact wiht a large asteroid may be enough to shift it's rotation angle and also melt a sea into it, so perhaps the giant new areas and the zones not exposed to sun(lighter ones) are due to impacts rather than heat inside of pluto. Pluto is perhaps similar to Europa which is 20% larger. .18 and .25 earth diameters.
bandybabboon
CC BY-SA 4.0
2015-07-22T11:26:54.800Z
2020-05-19T15:09:42.273Z
2020-05-19T15:09:42.273Z
bandybabboon
<p>It was predicted by some, before the images arrived, that Pluto's craters would be much shallower than perhaps on other rocky objects/satellites. The reason is the icy composition and the relatively low impact velocities in the outer solar system (<a href="http://adsabs.harvard.edu/abs/2015Icar..246..156B" rel="nofollow">Bray &amp; Schenk 2015</a>).</p>

<p>There are indeed reported quotes in recent days that there are no impact craters on Pluto (e.g. <a href="http://uk.businessinsider.com/pluto-surface-photos-no-craters-geologically-active-2015-7?r=US&amp;IR=T" rel="nofollow">here</a> or <a href="https://www.youtube.com/watch?v=ZAUMDv0XTb4" rel="nofollow">here</a>), based on the highest resolution images.</p>

<p>However, I'm with you - the things you have marked look like very large impact craters, or the remains of them, and so what we are seeing is that there are no <em>small</em> ones.</p>

<p>The gist of what I have heard/read is that this indicates geological activity on Pluto, which is effectively removing the evidence of relatively small impacts and that the surface we see is mostly younger than 100 million years old.
Watch this space, a lot of people are just flapping their lips at the moment (including me).</p>

<p>Another possibility - raised by Wayfaring Stranger - could be that the expected number of impacts was (hugely) overestimated. This is discussed by <a href="http://www.hou.usra.edu/meetings/craterstats2015/pdf/9031.pdf" rel="nofollow">Singer &amp; Stern (2015)</a>. There are indeed uncertainties, and it is hoped that cratering on Pluto &amp; Charon would help constrain the number densities and size distribution of small impactors. My impression is that the uncertainties could be at levels of up to factors of 10 - and this seems to be discussed quite carefully in <a href="http://adsabs.harvard.edu/abs/2015Icar..258..267G" rel="nofollow">Greenstreet et al. (2015)</a> (behind a paywall, sorry), who also comment in the abstract that surface ages judged from cratering are " entirely dependent on the extrapolation to small sizes [of the impactor distribution]".</p>

<p>Further Edit: LDC3 suggests all the craters could be too small to be seen. The high resolution images that have been released could resolve craters of a diameter of a couple of km or more and cover a few percent of the surface. According to <a href="http://www.hou.usra.edu/meetings/craterstats2015/pdf/9031.pdf" rel="nofollow">Singer &amp; Stern (2015)</a>, the number of craters at this size and above on Pluto <em>they expected</em> in such an area is $\sim 1000$. So I think that either the planet has been resurfaced recently, the craters have been eroded in some other way or their estimates for the number of impacts/size of the impactors is wrong.</p>

CC BY-SA 3.0
2015-07-18T13:09:24.433Z
We don't have good data on numerical density and size distribution of trans-neptunian asteroids yet, do we? Paucity of craters may just indicate fewer things to collide *with*.
Wayfaring Stranger
CC BY-SA 3.0
2015-07-18T13:40:10.743Z
Or maybe Pluto lacks craters because it has cleared its orbit? Maybe thanks to its orbitally resonant giant Neptune neighbor. And thus scoring the third criteria for being a a a..., no I won't write it out loud. You know what it is, Rob, now that you've seen it. ;-)
LocalFluff
CC BY-SA 3.0
2015-07-18T13:44:05.913Z
@WayfaringStranger Absolutely. I have added a citation to work that looks specifically at this issue. I do think that everyone is surprised by the lack of cratering though.
ProfRob
CC BY-SA 3.0
2015-07-18T14:03:44.143Z
I think we all expected something like Mercury or Callisto.
Wayfaring Stranger
CC BY-SA 3.0
2015-07-18T14:23:52.770Z
Rob, `what we are seeing is that there are no small ones.` I disagree with that; after all, Pluto is 1/3 the size of the moon and the craters (on Pluto) would be about the size of the smallest craters on the moon.
LDC3
CC BY-SA 3.0
2015-07-18T14:54:48.740Z
@LDC3 I am *repeating* what NASA scientists have been saying to all news outlets. What exactly do you disagree with? If you are suggesting the crater size distribution is similar to the moon then there should be many more small craters than the few large ones the OP has identified. There appear to be absolutely none in the higher resolution images. There is no evidence of any small craters. If they are below the image resolution that indicates a highly peculiar, discontinuous distribution.
ProfRob
CC BY-SA 3.0
2015-07-18T14:56:40.987Z
@LDC3 You are also incorrect to draw any inference from the size of the cratered body. Crater size depends on the (relative) velocity and mass of the impactor and the composition of what it impacts upon, not directly on the mass or size of the cratered object.
ProfRob
CC BY-SA 3.0
2015-07-18T23:05:58.390Z
It's icy surface and elongated orbit which lends itself to the melting and thawing of much of it's surface and that would explain why impact craters wouldn't last very long.
userLTK
CC BY-SA 3.0
2015-07-18T23:09:51.037Z
@userLTK You may have a hypothesis, but it was certainly not expected to occur. I believe that tidal heating has also been ruled out. The "mountains" suggest geological activity.
ProfRob
CC BY-SA 3.0
2015-07-18T23:10:25.407Z
@RobJeffries the planet's gravity does add to the minimum speed that a meteor or comet can hit it.   Also, the distance from the sun offers a guideline as to how fast an object is likely to be traveling (unless it's from another solar system but those are less common).   A rule of thumb, impact speed = Escape velocity + vector addition of planet's orbital velocity and object that hit's it's orbital velocity - which is bound by escape velocity at that distance from the sun.   In the case of Pluto, most impacts would be much slower than on the inner planets.
userLTK
CC BY-SA 3.0
2015-07-18T23:11:31.007Z
@RobJeffries  Oh well.   I thought that might be it.   I guess I should read up on Pluto a bit more.
userLTK
CC BY-SA 3.0
2015-07-18T23:16:57.730Z
@userTLK  The size of craters has nothing to do with the physical size of the cratered object. The acceleration due to the mass of Pluto is a perturbation. Yes of course the impacts are slower at Pluto's orbit - that is in the second sentence of my answer and is of course an obvious point, well known by all the people who predicted that many craters would be seen!
ProfRob
CC BY-SA 3.0
2015-07-18T23:22:41.453Z
@userLTK The mean orbital speed of Pluto is 4.7 km/s, compared to its escape velocity at the surface of about 1.3 km/s, so its mass really isn't much of a factor.
ProfRob
CC BY-SA 3.0
2015-07-18T11:26:35.510Z
2015-07-18T15:13:28.783Z
2015-07-18T15:13:28.783Z
ProfRob
<p>I've heard from a lot of sources that Pluto doesn't seem to have <em>any</em> impact craters, but I see a few things that look like impact craters, highlighted in this picture:</p>

<p><img src="https://i.sstatic.net/uL9HL.png" alt="Pluto impact craters"></p>

<p>For comparison, here's something I think looks like an impact crater on Pluto next to an impact crater on Mercury:</p>

<p><img src="https://i.sstatic.net/YwTvJ.png" alt="Pluto Mercury comparison"></p>

<p>Are they impact craters on Pluto?  If not, what are they?  If they are, why are people saying it has <em>no</em> impact craters?</p>

CC BY-SA 3.0
2015-07-18T07:32:36.777Z
"Not any" might mean "much fewer than expected". This is hand waving astronomy, not surgery. And hardly any craters have been found on the close up images. So it seems that Pluto's surface is more about internal processes than impact history. But maybe there are no large impactors out there?
LocalFluff
CC BY-SA 3.0
2015-07-18T08:42:06.323Z
Since there have been no images of Pluto that could have revealed impact craters before New Horizon's pass any statement more than ~a few weeks old would have been pure speculation. From the image you post Pluto clearly does have impact craters. From what I can see in the above photo the surface is covered with circular scars which appear to me to be relaxed impact features.
Conrad Turner
<pluto>
Does Pluto have impact craters?
Jez
# Does Pluto have impact craters?

(Asked by: username_0 on 2015-07-18)

I've heard from a lot of sources that Pluto doesn't seem to have *any* impact craters, but I see a few things that look like impact craters, highlighted in this picture:

![Pluto impact craters](https://i.sstatic.net/uL9HL.png)

For comparison, here's something I think looks like an impact crater on Pluto next to an impact crater on Mercury:

![Pluto Mercury comparison](https://i.sstatic.net/YwTvJ.png)

Are they impact craters on Pluto? If not, what are they? If they are, why are people saying it has *no* impact craters?

**Tags:** pluto

> **Comments:**
> **username_1**: "Not any" might mean "much fewer than expected". This is hand waving astronomy, not surgery. And hardly any craters have been found on the close up images. So it seems that Pluto's surface is more about internal processes than impact history. But maybe there are no large impactors out there?  
> **username_2**: Since there have been no images of Pluto that could have revealed impact craters before New Horizon's pass any statement more than ~a few weeks old would have been pure speculation. From the image you post Pluto clearly does have impact craters. From what I can see in the above photo the surface is covered with circular scars which appear to me to be relaxed impact features.  

---

## 2 answers

### Answer by username_6 on 2015-07-18. Score: 5 | Accepted answer

It was predicted by some, before the images arrived, that Pluto's craters would be much shallower than perhaps on other rocky objects/satellites. The reason is the icy composition and the relatively low impact velocities in the outer solar system ([Bray & Schenk 2015](http://adsabs.harvard.edu/abs/2015Icar..246..156B)).

There are indeed reported quotes in recent days that there are no impact craters on Pluto (e.g. [here](http://uk.businessinsider.com/pluto-surface-photos-no-craters-geologically-active-2015-7?r=US&IR=T) or [here](https://www.youtube.com/watch?v=ZAUMDv0XTb4)), based on the highest resolution images.

However, I'm with you - the things you have marked look like very large impact craters, or the remains of them, and so what we are seeing is that there are no *small* ones.

The gist of what I have heard/read is that this indicates geological activity on Pluto, which is effectively removing the evidence of relatively small impacts and that the surface we see is mostly younger than 100 million years old.
Watch this space, a lot of people are just flapping their lips at the moment (including me).

Another possibility - raised by username_7 - could be that the expected number of impacts was (hugely) overestimated. This is discussed by [Singer & Stern (2015)](http://www.hou.usra.edu/meetings/craterstats2015/pdf/9031.pdf). There are indeed uncertainties, and it is hoped that cratering on Pluto & Charon would help constrain the number densities and size distribution of small impactors. My impression is that the uncertainties could be at levels of up to factors of 10 - and this seems to be discussed quite carefully in [Greenstreet et al. (2015)](http://adsabs.harvard.edu/abs/2015Icar..258..267G) (behind a paywall, sorry), who also comment in the abstract that surface ages judged from cratering are " entirely dependent on the extrapolation to small sizes [of the impactor distribution]".

Further Edit: username_8 suggests all the craters could be too small to be seen. The high resolution images that have been released could resolve craters of a diameter of a couple of km or more and cover a few percent of the surface. According to [Singer & Stern (2015)](http://www.hou.usra.edu/meetings/craterstats2015/pdf/9031.pdf), the number of craters at this size and above on Pluto *they expected* in such an area is $\sim 1000$. So I think that either the planet has been resurfaced recently, the craters have been eroded in some other way or their estimates for the number of impacts/size of the impactors is wrong.

> **Comments:**
> **username_7**: We don't have good data on numerical density and size distribution of trans-neptunian asteroids yet, do we? Paucity of craters may just indicate fewer things to collide *with*.  
> **username_1**: Or maybe Pluto lacks craters because it has cleared its orbit? Maybe thanks to its orbitally resonant giant Neptune neighbor. And thus scoring the third criteria for being a a a..., no I won't write it out loud. You know what it is, Rob, now that you've seen it. ;-)  
> **username_6**: @WayfaringStranger Absolutely. I have added a citation to work that looks specifically at this issue. I do think that everyone is surprised by the lack of cratering though.  
> **username_7**: I think we all expected something like Mercury or Callisto.  
> **username_8**: Rob, `what we are seeing is that there are no small ones.` I disagree with that; after all, Pluto is 1/3 the size of the moon and the craters (on Pluto) would be about the size of the smallest craters on the moon.  
> **username_6**: @username_8 I am *repeating* what NASA scientists have been saying to all news outlets. What exactly do you disagree with? If you are suggesting the crater size distribution is similar to the moon then there should be many more small craters than the few large ones the OP has identified. There appear to be absolutely none in the higher resolution images. There is no evidence of any small craters. If they are below the image resolution that indicates a highly peculiar, discontinuous distribution.  
> **username_6**: @username_8 You are also incorrect to draw any inference from the size of the cratered body. Crater size depends on the (relative) velocity and mass of the impactor and the composition of what it impacts upon, not directly on the mass or size of the cratered object.  
> **username_9**: It's icy surface and elongated orbit which lends itself to the melting and thawing of much of it's surface and that would explain why impact craters wouldn't last very long.  
> **username_6**: @username_9 You may have a hypothesis, but it was certainly not expected to occur. I believe that tidal heating has also been ruled out. The "mountains" suggest geological activity.  
> **username_9**: @RobJeffries the planet's gravity does add to the minimum speed that a meteor or comet can hit it.   Also, the distance from the sun offers a guideline as to how fast an object is likely to be traveling (unless it's from another solar system but those are less common).   A rule of thumb, impact speed = Escape velocity + vector addition of planet's orbital velocity and object that hit's it's orbital velocity - which is bound by escape velocity at that distance from the sun.   In the case of Pluto, most impacts would be much slower than on the inner planets.  
> **username_9**: @RobJeffries  Oh well.   I thought that might be it.   I guess I should read up on Pluto a bit more.  
> **username_6**: @userTLK  The size of craters has nothing to do with the physical size of the cratered object. The acceleration due to the mass of Pluto is a perturbation. Yes of course the impacts are slower at Pluto's orbit - that is in the second sentence of my answer and is of course an obvious point, well known by all the people who predicted that many craters would be seen!  
> **username_6**: @username_9 The mean orbital speed of Pluto is 4.7 km/s, compared to its escape velocity at the surface of about 1.3 km/s, so its mass really isn't much of a factor.  

---

### Answer by username_3 on 2015-07-22. Score: 3

Further imagery has confirmed billion year old surface with impact craters on one part and younger which is very recent and smooth on another part.

Jeff Moore, of the New Horizons team has said. “We now know Pluto has some surfaces that are a billion years old,”

Edit... new estimate quote from NASA:
Based on the lack of impact craters, scientists suspect the surface of Pluto is less than a few hundred million years old,
Read more at [http://newsdaily.com/2015/07/nasa-spacecraft-shows-pluto-wrapped-in-haze-ice-flows/#ytDT3emJZSKRbL7b.99](https://web.archive.org/web/20150807092534/http://newsdaily.com/2015/07/nasa-spacecraft-shows-pluto-wrapped-in-haze-ice-flows/)

He expects that the bulk of the data that he wants to study wont have been beamed back before early 2016.
Large scale image:

[![http://pluto.jhuapl.edu/images/featuredImages/nh-pluto-mountain-range.png](https://i.sstatic.net/u6bGY.png)](https://i.sstatic.net/u6bGY.png)
[![boundary of old and new, old dateable by number of craters](https://i.sstatic.net/6GZb8.jpg)](https://i.sstatic.net/6GZb8.jpg)
[![recent zone similar to a convection surface](https://i.sstatic.net/WH6AI.jpg)](https://i.sstatic.net/WH6AI.jpg)

> **Comments:**
> **username_4**: This answer could really use some support for its claim. Such as the referenced image or the source for the claims of billion year old and relatively young surfaces.  
> **username_5**: @ufomorace Better (good enough for me to give it +1, anyway), but do you have a link to the article or whatever it was that gave the Moore quote?  
> **username_3**: Hi sorry i thought that the phrase would be in search engines... here: http://fortune.com/2015/07/15/nasa-pluto-data-earth/  
> **username_3**: Moore is a planetary geologist from Nasa, i don't know if he said that the surface is so old because he measured the craters or because of the black surface, will be cool to have further information. Given the size of pluto and the fact that it is ice, an impact wiht a large asteroid may be enough to shift it's rotation angle and also melt a sea into it, so perhaps the giant new areas and the zones not exposed to sun(lighter ones) are due to impacts rather than heat inside of pluto. Pluto is perhaps similar to Europa which is 20% larger. .18 and .25 earth diameters.  

---

