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Episode 30: Was the Asteroid Belt a Planet? Part 2

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Recap: Last episode was on mainstream evidence - or lack thereof - for the asteroid belt having been a planet. This episode gets to one of the pseudoscientific ideas, from Tom Van Flandern, of Mars being a moon of one of the planets that supposedly exploded to make the asteroid belt.

Solution to Episode 29's Puzzler: See Transcript

Additional Materials:


Last episode, I talked for awhile about the basic evidence for why the asteroid belt could not have been a planet. I got probably more feedback in the first few days of releasing that episode than any before, which I'll address after the main segment, but for now let's assume that I was right and that at least one of the four reasons I talked about last time is valid. This episode is going to focus more on debunking Tom Van Flandern, who probably is the one who most formalized the Exploding Planet idea.


Tom Van Flandern was a perfectly main-stream astronomer for many years before he went - what many would consider - a bit nuts and bought into the whole exploding planet idea. This is the basic idea that a fully-formed planet existed in the region of space now occupied by the asteroid belt, and that it exploded, the debris being today's asteroid belt. Van Flandern also hooked up with Richard Hoagland and bought into the Mars anomaly stuff which I will get into in future episodes.

Like Richard Hoagland, I don't honestly know if Van Flandern believes what he said. He sounds convincing in interviews. However, I heard from a coworker who knew Van Flandern and was very good friends with him that Tom stated he didn't really believe any of the stuff that he was saying. He said it knowing that it was all likely wrong, but on the very off-chance in 100 years that it would be found to be correct, he wanted to get credit for it.

This coworker said I could not use his ... or her ... name, and that's really only an anecdote, so I'll say what I said of Hoagland in Episode 26: I don't know if he believes the stuff he said, but other people do. And that's reason enough to get into it.

Van Flandern died in 2009 after living a fairly long life and giving several fairly long interviews on Coast to Coast AM. Some clips of which I'll play for you in this episode.

Planet Formation

It's usually best to start at the beginning, and in this case that would be with planet formation. Van Flandern had an interesting idea about planet formation - that of the fission idea, whereby the sun spins really fast and blobs get spit out that become planets.

That in itself deserves a separate episode, so I'm not really going to get into it here. But, a twist of Van Flandern's that's necessary to understand his scenario is that he proposed that instead of blobs of stuff getting spit out by the sun, you have pairs of blobs, one on each side, that get spit out. Now, why you wouldn't have triaxial symmetry and spit out three, or quadaxial and spit out four, I don't know.

But anyway, his scenario paints a picture of the original solar system where there were twelve planets: [Coast to Coast AM clip, June 30, 2003, starting 57:17]

How we got to our current situation is a story of planets exploding.

Exploding Planets

Specifically, Van Flandern thinks that planets could explode in any combination of three possible ways. The following is a fairly long clip, but I think that it's important to understand - or at least to hear - his ideas as he puts them rather than me summarizing them: [Coast to Coast AM clip, Hour 3, August 22, 2006, Hour 3, starting 0:45]

To summarize, his three ways are: (1) A phase change causes a rapid change of volume that creates enough pressure to explode the planet. (2) A nuclear reaction explodes the planet. (3) Magic streaming gravitons.

The first scenario, the phase change, has the problem of there simply not being a mechanism to do this. There is no known mechanism nor energy source that could vaporize enough material - or any material, for that matter - to explode a planet from the inside. And actually, the second scenario has the same problem. Yes, there is evidence for an isolated fission reaction on Earth due to an abnormally high concentration of natural nuclear material that the planet formed with. But, the ball remains squarely in Van Flandern's court - or whomever wants to carry the torch at this time since he's dead - to show that enough of this could occur in many planets' cores to cause several solar system planets to explode.

Which brings us to the third mechanism - magic streaming gravitons that planets can shield each other from that I guess causes them to maybe push together and collide and explode. This is another case where all because he says it does not mean I need to find a way to debunk it - it falls so far outside the realm of known science that he needs to supply the evidence for it rather than me spending hours explaining why it doesn't make sense.

Evidence on Mars

Which brings us to the present-day evidence part, which will comprise the rest of this main segment. After all, you can spout out whatever ideas you want, but if there is no evidence for it that can be found, then it should sit on the fiction shelf without anyone paying heed.

Fortunately for me, much of the evidence that Van Flandern points to has to do with Mars. I have spent the last 6 years studying Mars and doing both my Master's and Doctoral dissertations on Martian craters. And one of the main lines of evidence that Van Flandern points to is Martian craters.

To give you the relevant background information, Mars is the planet between Earth and the asteroid belt, and Van Flandern thinks that Mars was one of two moons of Planet V -- the planet blew up 65 million years ago and created the asteroid belt, and the other moon blew up 3.2 million years ago.

One of the main lines of evidence for this is Mars' heavily cratered southern hemisphere. For those who don't know, Mars is an interesting planet. Roughly speaking, the northern half of it is fairly smooth and shows relatively few craters. The southern half is topographically higher by a few kilometers - similar to Earth's ocean floors versus the continents - and it's heavily cratered. Just to give you a very rough idea, if we count up all the craters larger than 1 km in the northern hemisphere, there are about 70,000 versus 300,000. But, if you use data other than imagery, such as topography, you can find many larger craters similar in number to those in the southern hemisphere.

Another feature of the northern hemisphere is that the thickness of the crust, the upper layer of the planet, is significantly thinner. Something like 20 km thick versus about 70 km thick.

The prevailing hypothesis to explain this is a large impact very early in the planet's history, though other people have suggested things like an ocean or mantle plumes, similar to how the Hawai'i islands are made but on a much larger scale.

Van Flandern, though, explains it with an exploding planet: [Clip from Coast to Coast AM, Hour 1, June 25, 2008, starting 9:46 and then 13:46]

There are several problems with this, which brings us to the puzzler from last episode. Chew suggested one problem with this scenario would be that the debris would not all arrive at Mars at the same time, so the impact craters would not be confined to one half of it. This goes somewhat in-hand with Parrot's answer that the vast distances between objects in space that the debris would be so diffuse by the time they hit Mars that you wouldn't get such a large difference.

I suppose these could be correct if Mars, as a moon of Planet V, were orbiting pretty far away. But really, the problem with this gets to the timescales suggested: Mars' surface is old. From basic dynamics and what we know from the moon, the vast majority of Mars' craters formed more than 3 billion - not 65 million - years ago. The whole idea of crater age dating is yet another episode, so I won't go into it really here, but there are at least two ways to think about this to independently demonstrate that the craters need to be old and the northern plains need to be relatively young.

The first is simply to look at them. Young craters look sharp, fresh, with will defined rims, clean floors, and ejecta blankets. Most of the craters in the northern hemisphere look like this. Some in the southern hemisphere look like this. Only two of the large craters - and here I'm talking about the 200-km crater Lowell in the southern hemisphere and 222-km crater Lyot in the northern hemisphere - look fresh. And my recent work age-dating them puts them at about 3.8 and 3.5 billion years old, respectively. But again, you can ignore the age values and just look at how fresh they are. If the northern hemisphere is supposed to be older, then it's the southern hemisphere that should have the vast majority of fresh-looking craters.

The second is to argue from the standpoint of what we see on Earth's moon. We see a lot of craters. Pretty much everywhere except in the dark regions which are called "maria" (plural) or "mare" (singular) from the Latin meaning "sea(s)." I have not seen Van Flandern nor anyone else claim that the Moon experienced anything negative from Planet V's or the moon Velona's blowing up, so we could consider our moon's cratering record as indicative of what an inner solar system object should have experienced over the last 4.5 billion years. What looks most similar to the moon? Mars' southern hemisphere, not the northern. It's the southern hemisphere of Mars that seems to show a cratering record indicative of a surface that hasn't been significantly altered in the last 4 billion years as opposed to the northern hemisphere, which does.

I don't think at this point I need to invoke Occam's Razor, but I will: The standard model, as I explained it, can explain what we see of Mars much better than the exploding planet one, and it also introduces the least amount of new information.

Terran Craters

Another bit of evidence - fairly minor - that Van Flandern claims is craters on Earth: [Clip from Coast to Coast AM, August 22, 2006, starting about 7:00]

To say this is wrong is about as far as I think I need to go. Again -- I study impact craters. I'll link up to the global impact crater database in the shownotes that has age estimates for the ~180 identified craters on Earth in the shownotes. In it, I see two that date to around 65 million years ago, including Chicxulub, and two more are just listed as younger than 65 million years. There are also none indicated as dating from exactly 3.2 million years ago, though two are there that have error bars that overlap 3.2 million years ago.

I know he's dead so it's not entirely fair for me to say this, but the onus really is on him - or someone who wants to carry that torch - to come up with the evidence. Unfortunately for him, I study this stuff, and this is a case where I knew right off the bat that he was making stuff up. Or, just sorely mistaken.


And not to seem to end this topic when it seems like we may have just gotten started, but that's about it. I'll link up to Van Flandern's still active "Meta Research" website, but really, that's about all there is to the exploding planet idea. There are some more smaller details here and there, but really it's the Mars crater stuff that is usually highlighted, and he's just wrong about it. Mars' cratering record is pretty clear that it was the northern plains that were resurfaced, not the southern hemisphere that was blasted by debris 65 million years ago.

I suppose I could get into one bit that I heard one time I think by Hoagland that Saturn's moon Iapetus is evidence for this. Iapetus is the moon where one half is bright as snow and the other is dark as asphalt, and Hoagland says this is evidence for the exploded planet blasting Iapetus. Besides us actually having an explanation for this that has nothing to do with exploded planets (the explanation being that it's due to material left after ice sublimates away), it leaves the question of why would Iapetus be the only moon out of the 100 or so around Jupiter and Saturn to show this. So it's inconsistent, although inconsistency never has stopped Richard Hoagland.

So in the end, the exploded planet idea for the origin of the asteroid belt is the stuff of fiction. It's still used as plot devices in stories and movies, but it shouldn't be if you want to represent the real science.

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