Last week, when writing about potential discoveries in 2008, I admitted to having some specific ideas, some vague hopes, and that some might just happen. I wrote about some of my specific ideas for the year. Here I’ll talk about the other two – and the much more common – types of discoveries.
The “vague hope” types of discovery are very different from the “specific idea”, or, to be more specific, the make-a-hypothesis-and-test-it types of discoveries favored in explanations of the scientific method in 8th grade classes.
The best example from my own past that I can give us this type of vague hope was the discovery of Eris itself (the Kuiper belt object larger than Pluto that caused the uproar over Pluto’s status and finally forced the demotion of Pluto to a dwarf planet. You can read much more about Eris on my detailed site). When I started scanning the skies almost a decade ago looking for large objects in the outer solar system, I certainly didn’t know what specifically was going to be out there, but I knew that there was a not bad chance that we would find something bigger than Pluto eventually (though I will admit that at one point midway through the decade I contemplated declaring the search over, thinking we had found all there was to find of interest. One of my students eventually talked me out of it). On January 5th 2005 (3 years ago today, even though it feels like a much longer time ago to me), I finally spotted the object that we first called Xena -- then temporarily became named 2003 UB313 and finally became Eris -- moving very slowly past the stars on my computer screen. It’s not that we had had a hypothesis to prove, just a realization that if you search more of the sky than anyone else has since the invention of the computer and digital cameras, you will certainly find things that no one has before. Will the thing you find be bigger than Pluto? Maybe yes, maybe no, but, as long as you are hoping, you might as well hope in the direction of bigger.
Now to 2008. The survey of the skies that led to the discovery of Eris and the other dwarf planets ended more than a year ago when we finally had scanned almost all of the skies that can be seen from our telescope at Palomar Observatory. But after spending most of a decade searching the skies for newer and larger bodies, it was hard to actually quit. What to do? Start over again. But this time I am doing it with the knowledge gained from doing it the first time, so this time we are doing everything – I hope – right. In practice, the most important thing that this means is that we are extending the survey to find extremely distant objects that we would have missed the first time around.
Why? Vague hope. Or perhaps it is better called “directed hope.” From our discovery of Sedna, which spends most of its time far far away from the sun, we realized that there might well be many many objects out at those distances, and that some of them could be quite large indeed. By “large” here, I am talking about something perhaps even the size of Mercury or of Mars (hope. remember: the key here is hope). I certainly don’ t have a specific scientific hypothesis supported by equations and calculations that some such object is out there, just a realization that it plausibly could be and that no one has ever done a thorough search.
So that could be one very exciting answer for discoveries of 2008: a Mars-sized body orbiting at perhaps twice the distance of Eris. Amusingly, by the current IAU definition, such an object would still be called a dwarf planet, though it would be a dwarf bigger than some real planets. If we really did discover such a thing it would probably re-light the planet definition fire, and we would all get to watch astronomers begin arguing once again.
To be honest, I have to admit that I think finding such a beast is a bit of a long shot. The main reason is that even though I am pretty convinced that such large dwarf planets are out there floating in the same region occupied by Sedna, they are likely to be too far away for our modest telescope at Palomar Observatory to see. Really, we would have to get pretty luck. But again: directed hope. It just might be there, and we won’t know until we look.
Finally, some discoveries are the type that I said just happen, though, really, that is not quite the right phrase. No discover ever just happens, I don’t think, but, sometimes, while you’re looking for something else, or examining something just because you’re curious, or trying hard to understand one little detail of something that just doesn’t make sense to you, something will pop out that you had no idea was coming.
The discovery of Sedna was like this. We were scanning the skies hoping that we might find something bigger than Pluto, knowing that we were bound to find many things than no one had ever seen before, but we never anticipated anything like Sedna.
When I first saw Sedna I wasn’t even convinced it was real. It was so faint that I thought it might just be a recurring smudge on the pictures I was looking at. The first email I sent out to Chad Trujillo and David Rabinowitz, the two guys with whom I was working, said “Not that I think it’s actually real, but the thing I might have just found is really really far away and really really big.” It was true, which is why we are now looking for things even bigger and further away.
Sedna orbits in a region of space that astronomers expected to be essentially empty, so it really had never occurred to me that when we began hunting in the skies something like Sedna might show up in our snares. Sedna is smaller than Eris by perhaps 20-30% and thus smaller than Pluto, so it didn’t get nearly as much press coverage as the Eris discovery, but, of the two, Sedna is by far the much more interesting scientific discovery. Eris’s main importance is less in the scientific knowledge that something bigger than Pluto exists but much more in the cultural importance in that it was the discovery that finally drove home the fact that Pluto is not a unique oddball at the edge of the solar system but simply one of the largest members of a much more extensive population. But Sedna tells us something we never knew before. What? It is still not clear; we’re working hard to understand all that Sedna says, but by the time we are done I hope that Sedna is the beginning of an intricate story of the birth of sun in a crowded cluster of stars which eventually caused Sedna to be peeled out of the inner solar system to become part of this new still unnamed region beyond the Kuiper belt. Stay tuned. There are other possibilities for what it might mean. But whatever it turns out to mean will be something we never even considered when we first started looking across the sky.
What might we discover unexpectedly in 2008? There is no way I can tell, of course, but I can at least give some areas of possibility, because all of these accidental discoveries come about with a lot of hard work to make the accidents possible. If I had to place bets on what project is most likely to lead to something like this, I would have to again say the new sky survey. Anytime you are looking over vast areas of sky in ways that no one ever has before your chances of having a good accident are high. But that is not the only project my group and I are working on these days – we’re thinking about storms on Titan, giant collisions and icy atmospheres in the outer solar system and more – so one of the other projects may sneak in as a long-shot. Or something new may come along unexpectedly.
Happy third anniversary of the discovery of Eris, and hope for discoveries – expected, hoped for, and accidental in 2008.