How Do We Know How Old Stuff Is on the Moon?

Introduction

While this movie is branded under “Exposing PseudoAstronomy” for legal reasons, it has less to do with popular misconceptions/conspiracies/hoaxes and more to do with real science. This is my third more modern, lots of CGI movie, and my second to explain a research paper that I wrote.

In the movie, I go through how the lunar crater chronology is the fundamental basis for how we estimate the ages of surface events across the solar system. I also explain how my work affects the lunar crater chronology and what can be done to better constrain it.

I’m still waiting for a young-Earth creationist to claim that because of a factor of 2 uncertainty, 4.5 billion becomes 6.019 thousand.

I also wrote a blog post about this for The Planetary Society. Because it was posted there over two weeks ago, I think it’s fair game to repost here. You can click on any of the images for larger versions, and all of them are screenshots from the YouTube movie.

Planetary Society Blog Post

Three years ago, I started a project to replicate work done by various groups in the 1970s and 1980s. When the project was completed, the result implied that much of what we think we know about when events happened in the solar system were wrong, needing to be shifted by up to 1 billion years. I presented this in a talk at the recent Lunar and Planetary Science Conference at 8:30 AM, when most people were learning about the latest results from Ceres.

The project started simply enough: I downloaded some of the amazing images taken by NASA’s Lunar Reconnaissance Orbiter’s Wide-Angle Camera (WAC) that showed the Apollo and Luna landing sites. Then, I identified and measured the craters (my dissertation work included creating a massive global crater database of Mars, numbering about 640,000 craters).

The reason to do this is that craters are the only proxy we have for ages on solid surfaces in the solar system. We can determine the relative age of one surface to another (is it older or younger?) by looking at which has more craters: The surface with more craters will be older because, when you assume that craters will form randomly across the body, then the surface with more craters has had more time to accumulate them.

Basic principle behind this work. (Background image © NASA/ASU; composite © S.J. Robbins.)

If we want to use craters for an absolute timeline – as in, actually put numbers on it – then we need some way to tie it to real ages. This was made possible only by the United States’ Apollo and the USSR’s Luna missions that returned rocks from the moon that could be radiometrically dated in labs on Earth.

With these radiometric ages, we then identify the craters on the surface those rocks were gathered and say that a surface with that many craters per unit area is that old.

That’s the lunar crater chronology: The spatial density of craters larger than a standard size versus radiometric age (we use 1 km as that standard size). This crater chronology is then scaled and used as a basis for the chronology across the rest of the solar system. When you hear someone say that something on the surface of Mars is X number of years old, chances are that’s based on the lunar samples from the 1960s and 70s and the crater counting done 40 years ago.

Example landing site area, Apollo 15 (yellow star). Blue outlined areas indicate regions on which craters were identified, blue shaded areas were removed because they are a different type of impact crater, and blue circles are the craters mapped and measured. (Background image © NASA/ASU; data and composite © S.J. Robbins.)

And, that’s where my project came in. While the rock samples have continued to be analyzed over the decades, the craters were not. It’s easy to assume that the researchers back then did a great job, but by the same token, science is about replication and re-testing and we have developed new ways of doing things in the crater community since the Apollo era. A simple example is that the crater chronology requires a spatial density, and therefore you need to know the area of the surface on which you have identified craters. Over the past 40 years, we have better understood the shape of the moon and now have computers to allow for much more precise area calculations. This can result in changes by 10s of percent in some cases.

When I had finished my reanalysis, my results differed for many of the landing sites, in some cases by a factor of 2 from what the standard is in the field. I was surprised. I checked my work and couldn’t find any mistakes. So, I combed through the literature and looked to see what other people had published. I ended up finding a range of values, and only in one case was my result at the extreme low or high of all the published results. I showed my work to colleagues and none of them could find any issue with it. So, eventually I published it, early last year.

The new (blue) and old (red) chronologies and the data used to fit the model. The vertical axis shows the spatial density of impact craters larger than or equal to 1 km in diameter, and the horizontal axis shows the age of the surface from radiometric dating of collected rock samples. (© S.J. Robbins)

When I fit my crater data to the radiometric ages, my fit function showed a difference with the standard that has been used for three decades: Surfaces assigned a model age of about 3.5 to 3.7 billion years under the old chronology were older, by up to 200 million years. And, surfaces younger than about 3.4 billion years under the old chronology are younger, by up to about 1 billion years.

The new and old chronologies in blue and red (top), and the difference between them in terms of model surface age. (© S.J. Robbins)

There are a lot of implications for this. One is that volcanism on the terrestrial planets may have extended to more recent times. This would imply that the planets’ cores stayed warmer longer. Another implication is that the large reservoirs of water thought to exist around 3 billion years ago may have existed for another 500 million years, with implications then for favorable environments for life.

But, something that I added near the end of my LPSC talk was the question, “Am I right?” The answer is an unsatisfying, “I don’t know.” I of course would not have published it if I thought I was wrong. But by the same token, this type of science is not about one person being right and another being wrong. It’s about developing a model to fit the data and for that model to be successively improved as it gets incrementally closer to explaining reality.

And, there are ways to improve the lunar chronology. One that I’m a big advocate of is more lunar exploration: We need more data, more samples gathered from known locations on the moon’s surface. We can then date those samples – either in situ or in labs on Earth – and along with crater measurements add more tie points to the lunar crater chronology function. Right now, there is a glaring gap in the sample collection, one that spans 2 to 3 billion years of lunar history. A single point in there could help differentiate between my model and the classic model. And more data would be even better.

Until we land robotic missions to send back samples from other planets or that can date samples there, the moon is still our key to ages across the solar system.

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Podcast Episode 40: Crater Age Dating Explained, Part 1

This is a bit of a longer episode. ‘Cause, this is what I do.

I give you a pretty detailed overview of how crater age dating works, the difference between absolute and relative age dating, how we can assign absolute ages to the relative ages of craters, how geologic mapping works and why it’s important for crater age dating, and then many of the known problems and caveats with the method.

Finally, there’s an open question about the puzzler: Is it worth doing? I wanted to do it initially to get interaction between me and the listeners. But participation has been around 1 for each. So if you have any opinion regarding the Puzzler, please let me know in the Comments to this post.

When Encyclopedias Are Bad: A Closer Look at Conservapedia – “Mars”

Introduction

Last week, I wrote an article about how Conservapedia calls “black holes” and “dark matter” “liberal pseudoscience” in a very “huh?” moment. It still is confusing to me why they would waste mental energy on calling those things “liberal pseudoscience.” But I digress.

I thought I might take a closer look at some of their actual astronomy articles. Since I’ve been studying Mars for the last 4 years fairly in-depth, looking at their article on Mars seemed like a natural article to take a peek at.

I found what I expected – creationism and “problems for evolutionists” – but I also found what I didn’t expect – gross errors in information and zero references to back up most of what was stated.

The Good

I’ll start out by showing that I’m not completely out to “diss” Conservapedia. Their article has some good things. It correctly states that Mars is the 4th planet from the sun, for example. It gives the interesting factoid that researchers with missions on the planet will often adopt a “Mars day” work schedule that’s about a 25-hr day (as opposed to Earth’s 24-hr day). It talks correctly about what causes seasons on Mars. It even (mostly) correctly discusses the whole “face on Mars” issue.

The “Eh, That’s Wrong, But It’s Minor”

Let’s first deal with some assertions. Specifically, near the beginning, it states that Mars’ 26-month synodic period makes it a “particularly difficult object to explore, [sic]because opportunities to launch a rocket probe to Mars occur so far apart in time.” Rather, Mars is pretty much the easiest planet or planet-like object to get to by spacecraft, except for our moon. It’s close by, there’s NO WAY that the world’s space programs are funded enough to make craft to visit the planet more often than every ~1.5-2 years, and we can actually land on it and survive as opposed to the actual closest planet to us – Venus.

Towards the end, it discusses exploration of Mars. It states, “Mars has been the subject of more attempts to explore it, and more failures, than any other planet.” This is wrong. To-date, at least based on NASA’s Chronology of Venus Exploration and Chronology of Mars Exploration, Mars has had 40 missions, while Venus 43. Minor, but still a mistake.

Under their “Young Mars Creation Model” (see below for more on that), it states, “Discoveries by the Mars Excursion Rover Opportunity have led …” Unfortunately for Conservapedia, The MER craft acronym stands for, “Mars Exploration Rover,” not “Excursion.” Minor, but slightly humorous.

The Bad

Note: This section will not address the creationist stuff, look to the next for that.

I was reading through the page and the biggest thing to stand out was the following two paragraphs:

“Mars contains the largest of three major geologic features in the Solar System. The largest impact basin, the largest volcanoes and the largest canyon are all found on Mars and in a clear relationship to each other. This relationship provides the key to understanding Martian geology.

“Mars’ largest impact basin is called Hellas. As shown in the topography map, on exactly the other side of Mars from Hellas is Mount Alba Patera, the largest volcano by surface area. This antipodal juxtaposition suggests that the Hellas impact caused the eruptions of Alba Patera and the volcanoes of the Tharsis plateau to the south and southwest. To the east is found the gigantic rift valley called Valles Marineris.”

Alright, there are a few things here. First, a very minor one. “Alba Patera” is the name of the volcano, not “Mount Alba Patera.” When features were originally assigned names when we got the first good images back from spacecraft, “Mons” (singular) / “Montes” (plural) were given to very large and obvious mountains, “Patera” (singular) / “Paterae” (plural) were assigned to very large, irregularly shaped features, and “Tholus” (singular) / “Tholi” (plural) were assigned to “small” mountains or hills. Nothing has two designations. And later imagery revealed some of the montes, paterae, and tholi were volcanoes.

Moving on, I don’t want to concentrate on the whole Alba Patera is antipodal to Hellas Basin. Suffice to say, the ages don’t really work out. It’s possible, but it is no way a given that this is the case.

Rather, I want to focus on the other information given on Hellas: According to this article, Hellas Basin is the largest crater on Mars, and it’s the largest crater in the solar system. Wow.

In a word: NO.

First off, let’s put some numbers down. Hellas Basin< is very roughly 2200 km across and about 9 km deep (it’s difficult to measure the diameter because no one actually knows where the rim is, so you have different people making different estimates). For comparison, that’s just friggin’ big. It’s well over half the size of the United States.

But it’s not the biggest in the solar system, and it’s not even Mars’ largest.

Check out Utopia Planitia on Mars. It’s pretty much due north of Hellas, and it pre-dates Hellas by roughly 400 million years. It is also roughly 50% larger than Hellas, having a diameter of about 3300 km and being about 4-5 km deep on present-day Mars. Now that’s big. But to be fair, I suppose that Conservapedia’s article can be saved if we say that by “biggest” they mean “deepest.” Oh, and if you want to play around on Mars, looking at various features, I highly recommend Google Mars.

Anyway, Utopia is by far the largest impact basin on Mars. Or is it? The largest topographic feature on Mars is its crustal dichotomy – the north is low and flat and young (at least its visible surface), while the south is high and hilly and old. Again, check out Google Mars and zoom out. There have been many, many explanations proposed for this dichotomy, but the latest one to be shown to be viable is that of a really really big impact, very early in Mars’ history. Being a guy who studies craters, I like this idea, but I do think it has awhile to be shown somewhat conclusively. In this case, it is possible that even Utopia is just second place to an impact “basin” that covers nearly half the planet.

Moving on, though, we have the moon. Discovered on the lunar far side about 50 years ago resides the South Pole-Aitken Basin. This thing is also big. It’s about 2300 km in diameter – so bigger across than Hellas but not Utopia – but a whopping 13 km deep. So now, our goal of saving Conservapedia’s article by saying “biggest” means “deepest” doesn’t work, either. Oh, and there’s also Google Moon to have fun with.

The Creationist Take

In any normal article talking about Mars, I don’t think anyone would expect sections about young-Earth creationism. But, *gasp*, Conservapedia does.

It first shows up in the discussion about Mars’ magnetic field. There is none. There are pockets of crustal magnetism that locally are stronger than Earth’s, but there is no global magnetic field. In the section on Mars’ “magnetosphere,” it directly refers to Russell Humphreys, who is a creationist whose ideas I’ve discussed on this blog before.

It next comes up in the entire section on, “Problems for Uniformitarian Theories” (that’s code for old-Earth) that talks again about Mars’ magnetic field. Except, rather, it talks more about how Mercury’s magnetic field is an open question for astronomers rather than Mars’.

Finally, we get to the entire section, “Young Mars Creation Model.” I’m not entirely certain how anything that they discuss in the section actually supports their conclusion of: “This shows that, like Earth, Mars has evidence that it is only a few thousands of years old and not 4.6 billion years old.”

It does state, “The dating of [Hellas basin formation triggering Alba Patera’s volcanism] from craters places it at about the time of the Great Flood on Earth.” Of course, this is completely uncited. But being someone who actually studies craters on Mars and has the largest database of said craters in existence, I can unequivocally state that the craters on Mars’ present-day surface show it to be ancient – over 4 billion years old.

Final Thoughts

Perhaps I’m being unfair. After all, the editor of the page that put up the bulk of the information I talked about has no background in astronomy. Rather, he’s in charge of Conservapedia’s attempt to re-write the Bible. And in the spirit of Wikis, perhaps I should attempt to edit the page myself to make the corrections (fat chance …).

But rather, I think this serves as an example of two things. First, it’s another example of how Conservapedia should not by any stretch of the imagination be considered a good source for scientific information.

Second, it shows that encyclopedias in general should not be taken as gospel. Students should not use them as their source material. They may use them as a starting point, but they need to look at the references, evaluate them, and in the end find actual original source material.

On the Importance of Scientists to Publish in the Scientific Literature AND Other Venues

Introduction

This post isn’t actually about the process of peer review. It isn’t about the importance of press releases. It’s not about scientists going to conferences and hobnobbing with colleagues. Rather, it’s a tale of hope, joy, and crushing disappointment.

My Research

For very astute readers, you may have picked up bits and pieces of my current research, though I’ve never actually gone into any depth on this blog as that’s not the point of the blog. However, it forms the backdrop of this tale of woe:

My work has – for the past two years and for another year yet to come – been to create a new database of craters on Mars, statistically complete to diameters of about 1.5 kilometers. That’s about 170,000 craters larger than that size, though the database has around another 110,000 craters that are smaller in order to ensure statistical completeness. One of the goals of this database is to study a particular type of crater against the backdrop of other “less interesting” craters. The type I’m studying in particular are known as “lobed craters,” craters with “lobate debris aprons,” or “layered ejecta” craters. Everyone has their own pet term though the Mars Crater Consortium has tried to standardize nomenclature for them to be “layered ejecta.” The picture below illustrates a simple example of this type.

Single-Layered Ejecta Crater, Mars

The basic idea is that this crater’s ejecta is very cohesive and does not look like typical ejecta that we observed on the moon for years before we went elsewhere in the solar system. Layered ejecta craters exist almost exclusively on Mars, though a few have been observed on some of the outer planet satellites, namely Ganymede and Europa.

The main hypothesis for their formation is that the impactor hit a surface that had solid volatiles in it (as in ice). The volatiles melted into the surface from the impact energy and caused the ejecta to act as a cohesive “mudslide,” giving the appearance we see today.

Moving Forward – The Discovery

Now, in my research, I’ve noticed that double-layered ejecta (craters surrounded by not just one, but 2 layers of this cohesive ejecta) seem to be concentrated around volcanic terrain on Mars. While I was busy cataloging and outlining these lobes a few weeks ago, I noticed that there was a marked increase of the double-layered ejecta in a certain region of the planet. But there wasn’t a volcano there, I thought.

I zoomed out on the map I was using and, lo!, I saw what appeared to be a volcano. In fact, the caldera of this thing was about 75 km by 90 km, or around 50% larger than the state of Delaware, several times larger than the caldera of the Yellowstone supervolcano. This size would put it easily in the top 25% of caldera sizes on the planet Mars.

Taking a step back, another, side-project that I’m working on is creating mosaics of the large volcanos of Mars and performing crater counts within them in order to develop a timeline for the “last gasps” of volcanism. I had a list of 24 volcanos that I had obtained from the USGS last summer, since they keep lists of things like that. And I knew that this new caldera I found was not on my list.

Checking Around

So my next step was of course to check all the lists of known volcanos that I could find for Mars. I re-checked USGS. I even checked Wikipedia. But this feature that looked like a caldera was not on them.

Unfortunately, my advisor was in Antarctica searching for meteorites, so I could not consult with him. Rather, I talked to the post-doc next door, who looked at it and agreed with me that it appeared to be a volcano. On a day when his officemate was there, another post-doc, I asked her, and she wasn’t as certain that it was a volcano, but said it was possible. She suggested I check with some other people outside of the university, but I wanted to wait until my advisor was back to check with him … after all, I didn’t want to make myself look like a fool in front of possible future colleagues.

Spreading the Possible Word

Meanwhile, I was getting excited. I mean, who wouldn’t? I tried not to get my hopes up, but from what I could tell, this thing sure looked like a volcano, not a crater (I knew what an impact crater looked like … I’d been circling them for years). And it wasn’t on any of the lists for Mars volcanos. So I mentioned it to a few people, including a comment on The Conspiracy Skeptic podcast episode from a week ago that some of you may have listened to.

Advisor Returns

My advisor got back to this continent this past weekend and we arranged a meeting for yesterday (Monday) to go over progress on what I’d done for the past 10 weeks while he was gone. I told him the first thing I wanted to talk about was this possible volcano to see what he thought. He seemed fairly excited, too, and I think had briefly looked at it and thought it looked promising.

I went into his office at 1 for our meeting and sit down on the couch, and I said that the first thing to talk about would be this possible volcano discovery. He said something to the effect of, “Yeah …” and handed me a paper, turned to a color picture, with big arrows pointed at my volcano.

The Reaction

I was not happy. Duh. But, as far as I could tell, I had taken the right steps. I’d identified a feature I thought was something interesting. I’d created a high-resolution image of it. I’d checked with a few people, and I’d looked at the standard lists.

The paper that this was tucked away in didn’t have a revealing title, so it’s also not as though I had something I could easily search for. At the time of writing this, I can’t actually find the paper in question, though I did just find an abstract for a conference from 2008 where they identify it. Sigh. The abstract is entitled, “New Evidence for a Magmatic Influence on the Origin of Valles Mariners.” Their paper from last year had a similar title. As you can see, nothing in the title about “volcano.”

Final Thoughts – The Moral

The point of discussing this in my blog is to point out the importance for scientists that, once they make a discovery, they need to not just publish in the standard scientific literature. They also need to make sure that it makes its way to other publications, such as standardized lists so that other people don’t get their hopes up on making a discovery others know of it and can easily find that information rather than doing a very exhaustive literature review. The USGS lists are meant to be used by people as a guide for this sort of thing. But, in my bitter opinion, this was a “science fail” by the authors in terms of publicizing their discovery.

Is Saturn a Young System? Apparently, According to the Institute for Creation Research

Introduction

In the last few days, I’ve seen a few blog posts about Saturn being a young system on the usual creationist sites or those responding to the creationist sites, and being a bit behind in my blog, I thought I’d check out the usual suspects. Predictably, I found the article posted yesterday, May 7, 2009, on the Institute for Creation Research by my own favorite, Brian Thomas (who I picked apart in this blog post.

The article in question now is entitled, “Planetary Quandaries Solved: Saturn Is Young.” Okay, I admit I needed to take a deep breath with this one before reading it. After all, you’d think that if scientists had really discovered that Saturn had been created/formed recently, it would be all over the news, right? So right off the bat, the title is misleading, but understandable for a creationist website.

Then I picked through some of the references. Why? Because I actually do research on Saturn’s rings. I will be submitting revisions to a 50-page manuscript to the journal Icarus in the next 3 days that should be published in a special edition of the journal at some point this summer, and the conclusions from my simulations are that the ring system is at least 2 times as massive as before, likely more, and the implications are that the system can then easily be a corresponding amount older (e.g., at least 2 times older).

And, lo!, one of the references in the article directly cites my work — a ScienceNews article from September 2008. (Check out paragraph 4 of the article.) So now, it’s personal — Brian Thomas is using MY research (in part) to advance his creationist agenda, and I will not be silent about it. Hence this blog post. 🙂

What Is the Evidence the Saturnian System Is Old?

Let’s ignore all of the outside evidence that it’s old. Let’s ignore solar system formation models. Let’s ignore standard conventional wisdom. Let’s ignore the scientific problems about biblical creation. What is the evidence that the system is old, or at least not young.

Well, being a crater counter when I’m not running simulations of Saturn’s rings, I point to craters. Craters are used throughout the solar system as the only cross-planetary method of relative dating methods. In other words, how many craters a solid object has is the only thing that we can measure, at present, that gives us the relative ages of two solid surfaces.

Crater ages have been calibrated via Apollo lunar sample returns, and so – at least for our moon – we know that a certain number of craters per unit area corresponds with one age, and a different number corresponds with a different age — and we know what those ages are to reasonable accuracy for the moon.

Much work has been done and is being done to try to extrapolate what we know from our moon to other solid bodies, including Mercury, Venus, Mars, and the giant planets’ satellites. While the work isn’t perfect and uncertainties remain, the state of the research is that we can tell the difference between an object that is 6000 years old or 4 billion years old.

The surface of Titan? The last number I saw is that there are around 150 impact structures that have been observed, so the present-day surface age of Titan is reasonably young. Yes, I admit that — I’m not hiding it.

What about the surface of the other moons, such as, say, Iapetus? Well, take a look at the image to the right. There are A LOT of craters there, and the surface age of Iapetus is likely on the order of a few billion years (I say “likely” because I haven’t actually done the crater counts there). Now, unless you’re going to engage in some very special pleading, this is pretty good independent evidence that at least some parts of the Saturnian system is old.

Enter the Argument for Youth: Saturn’s Rings

I grew up reading that Saturn’s rings were young – probably formed only 100 million years ago after the breakup of a medium-sized moon, about the size of Saturn’s moon Mimas (shown on the right). That was based on a few things, including estimates of its mass from Voyager data as well as spectroscopic observations showing that the rings are fairly “fresh,” showing relatively little contamination by, basically, space dust.

This was still the predominant idea in 2002, when Jeff Cuzzi made his quite that Brian Thomas uses in the second paragraph of this article:

A history of mystery surrounds the youthful features of Saturn’s rings. Jeff Cuzzi, a planetary scientist at the NASA Ames Research Center, said in 2002, “After all this time we’re still not sure about the origin of Saturn’s rings….There’s a growing awareness that Saturn’s rings can’t be so old.” Cuzzi said, “There are two reasons to believe the rings are young: First, they are bright and shiny like something new. It’s no joke.” Indeed, after millions of years, the icy rings should have collected so much space dust that they should be charcoal-colored by now. Second, after only a few million years, the little moons embedded among the rings should have “flung away. This is a young dynamical system.”

And, this was still an issue in 2006, when I was just starting my simulations. The third paragraph of this article cites Josh Colwell in a presentation he gave. He was listing some of the current problems in a few-billion-year-old rings system, but the problems were still based on old data estimates for both the mass of the ring system and the viscosity of the particles (viscosity can be thought of as how well particles can transfer energy from one to another or how well they flow — water is not very viscous but molasses is).

Enter the simulations. I use Mark Lewis’ code for these simulations, and I make a point of that because Mark is quoted in the fourth paragraph of the ICR article:

Mark Lewis of Trinity University in San Antonio cautioned that it is still not known how they really clump. “It isn’t as straightforward as saying that high-density particles would lead to more clumping.”

This is true. There are many different parameters that go into these simulations to model the physics involved. Even though I explored a huge range of parameter space in my simulations, performing over 150 different N-body simulations that took over 27,000 CPU hours to run, I still did not explore the whole range of space, and a few of those parameters do affect how ring particles clump together.

Clumping is important because it directly affects how we estimate the mass of the rings. If the rings do not clump at all, then for every particle it will block an equal amount of light. Kinda like if you spread a lot of sand on a sheet of paper and you spread that sand evenly around, you will only see a little of the paper through the sand. But, if you use the same amount of sand and start to make little sand piles, you will see more and more of the paper.

That’s how we estimate the mass of the rings – by how much paper (how much light) can be seen through the rings. And, if the ring particles are clumped together, then you need many more ring particles to get the same amount of light blocked. What my simulations show is that clumping plays a much larger role than previously thought, and so we need more material in the rings to match the observed light-blockage.

Why do more massive rings mean that the ring system is older – or can be older? Because more massive rings means the viscosity is higher and so they spread out more slowly (one of the arguments they were young is that they would spread out too quickly). Also, it means they can be older because the same amount of pollution will get spread out over a larger area, and hence they won’t be as “dirty.” So, arguments that they are young because they don’t show a large amount of pollution can be answered that the pollution is just better hidden than we thought because there is more material within the rings to get polluted.

What was the connection to me here? Well, they’re my simulations. And that fourth paragraph has a quote from an article that talked about my results. Hence why I take this a little personally.

Moving On to Enceladus

In paragraph 5 of his article, Brian Thomas says that Saturn’s moon Enceladus “shows no hint of being 4.5 billion years old, but instead appears remarkably young.” I’m not going to harp on Brian’s grammar mistake here because I’m sure I have made my fair share of mistakes in this article grammar-wise, but I will say that it’s a poor journalist who doesn’t know what a sentence fragment is.

Anyway … this statement is simply wrong. It is true that the geysers that were discovered coming from Enceladus’ south polar region were a surprise, and they have made many people in the planetary community excited to find out why they are there. (Note – yes, new discoveries that challenge old models make scientists happy, not upset, as creationists would have you believe.) And a lot of Enceladus’ surface does appear to be young. However, a fair portion of the surface also appears to be very old, as shown in the picture on the right. Yes — I’m talking about all those craters.

Final Thoughts

That’s really the point of this article. So, no, the planetary quandary has not been “solved” to say that Saturn is young. Rather, the ring system can still easily be old based on the latest (and if I do say so myself, the greatest) simulations, and even though some features of Enceladus appear young and active, there are other parts of the moon that tell the tale of being ancient.