Okay, so I have Pluto on the brain. I admit it. New Horizons is the last probe to visit a world we haven’t yet visited, so it’s really big news. It’s exciting to think that all our preconceived “views” of Pluto will get blown away just three weeks away from close flyby of this dwarf planet and its moons. Heck, they’re getting blown away each time the folks on the mission issue another image.
But, there are other cool stories going on right now, so let’s spread around a little planetary mission love!
The mysterious glowing white dots of Ceres. What are they? Courtesy NASA/DAWN mission
First of all, the Dawn mission at Ceres keeps cranking out the great images of that dwarf planet. It’s mapping Ceres at high resolution, and on each orbit, it picks up more details of the surface.
The bright white dots that have so intrigued everybody are still…intriguing everybody. It’s not clear why they exist and what they are, but they have the planetary scientists considering many possibilities. Ice and/or salt deposits are two of the many suggestions about what they are. How they got there is still a mystery.
Craters, sunken “graben-like” areas, what looks like a cliff, and a pyramid-shaped mountain also grace Ceres’s surface. NASA/DAWN msision
What else has Dawn seen? Not surprisingly, for a world without an atmosphere and orbiting in the Asteroid Belt, there are many craters. We also see long sinuous lines that could be cracks, and in one area, a pyramid-shaped mountain that rises up about 5 km (3 miles) above the surface. And, it looks like there are more white spots scattered around the rest of the surface, too. All in all, Ceres is giving us quite a show, and the mapping has only just begun!
The other story that caught my eye this past week is the evidence of active volcanoes on Venus. Now, we’ve known for a long time that Venus is a volcanic world, and studies of its atmosphere have telltale signs of volcanic eruptions. But, no one has ever seen an eruption there because of the heavy, dense cloud cover that obscures our view of the surface.
Thermal (heat) mapping of the Venus surface show hot spots in the region of a volcano called Ozza Mons. Courtesy Ivanov/Head/Dickson/Brown University.
Astronomers spotted some interesting data in observations made by the European Space Agency’s Venus Express mission and thermal (heat) images made by the spacecraft’s Venus Monitoring Camera. It recorded some temperature spikes that just happened to coincide with known hot spots on the planet’s surface. Those hotspots flared up and then slowly faded down, in a manner very similar to what an Earth-bound volcano does when it erupts a lot of material for a while and then slows down. The planetary scientists took this as strong evidence that Venus volcanically active now. That also means that it’s active in its interior, too.
The news from Dawn, New Horizons, Venus Express, as well as Cassini and the swarm of probes at Mars is certainly extending our golden age of planetary exploration. And, now that NASA has committed to a mission to Europa, it looks like that age will continue. Revel in it folks! There are only a few times in history when so much has been discovered on behalf of all of us by our scientist friends and neighbors!
Check out this new video from the National Space Society. It’s an inspiring look at the exploration of Pluto — the world that’s going to break open our understanding of the last unknown part of the solar system — the Kuiper Belt and Beyond.
You know what I get from this video? That we’re on the doorstep of something big. The exploration of Pluto is bigger than squabbling over definitions. This is big science at its best, and it’s unveiling a world we’ve never seen up close. The last time I had that feeling was when I followed the Voyager missions to Jupiter, Saturn, Uranus, and Neptune. It’s THAT big. Even bigger, in a lot of ways.
Still, like any other big exploration effort, Pluto doesn’t come without controversy. There’s that whole “is it a planet or isn’t it” mess, largely foisted onto planetary science by non-specialists and then picked up by the media as a diversion. Of immensely MORE importance, there the more scientific questions about what Pluto is made of, how and where it formed, and what its moons are like. We’ll get answers to those, very soon.
Is Pluto a planet? Sure! It’s a special subcategory called “dwarf planet”. We all get that from New Horizons mission Principal Investigator Alan Stern, who began using the term ages ago (and I’m not sure who first coined it) to indicate that Pluto (and its siblings in the Kuiper Belt) aren’t quite like the other planets. But, this little world out there is the gateway to something wonderful.
People get all hung up on that “dwarf” thing and don’t even notice that “dwarf” is trying to tell us something. We have dwarf stars and dwarf galaxies — and yes, I know I’ve said this before, but I’ll keep saying it until people figure out that “dwarf” is not an insult.
“Dwarf” is telling us something about the size and evolutionary history of this planet and others like it. It’s a term that lets us know something about Pluto (and other dwarf planets) that differentiates them from gas giants and rocky planets and giant Neptunes and hot Jupiters and all the other types of planets that exist here and in other stellar systems.
Pluto and New Horizons as it will look in just a few weeks. Courtesy Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)
For my money, “planet” is a term that should really be a very wide definition of worlds — a sort of continuum of types of worlds around a star. In the case of the solar system, that continuum contains rocky worlds, gas giants, ice giants, and dwarf planets. That’s big change from a century ago, when we had rocky worlds and gas giants. And, before that, we simply had Greek tales of “wanderers that weren’t stars”. Before that, Ugg and Blogg sat outside the caves seeing “things that are bright in the sky. Some move. Some don’t. Let’s hunt some more bison tomorrow.”
Flash forward through 10,000 years of history between them to us, and today we know a LOT more about those things in the sky.
You see what I’m doing here: I’m showing you that the definition changes as we understand more about the worlds we find here and elsewhere. But definitions don’t dictate what things ARE. Over the years, people have disagreed on the definition of what they were seeing in the sky, but that didn’t change the essential nature of those objects.
In a few weeks, Pluto will blow whatever definition of “planet” or “dwarf planet” we have right out of the water. Heck, at the rate cool images are coming in from New Horizons, we’ll be seeing vivid proof of planet Pluto and its never-before-seen secrets materialize on our computer screens sooner than we think!
Interviewed in an article over at Popular Science, Alan Stern has confidently predicted that our perceptions about Pluto are about to change, in more ways than one. “I think that one of the things that will come out of the New Horizons mission,” Stern opined, “is that the public will take a look, and they won’t know what else to call Pluto but a planet, and a pretty exciting one.”
Alan and I have chatted about this a few times over the past year or so. For those of us who are scientist-types, Pluto represents a type of world that we first realized existed in great numbers only within the past decade or so. It’s a frozen outpost of what we once thought was a lonely, frigid part of the solar system. Pluto and its siblings and Kuiper Belt neighbors, along with the countless cometary nuclei that roam the outer solar system, hold clues to understanding what conditions are like “out there”. Not only that, but they have secrets about what it was like in the earliest epochs of our solar system’s history. Secrets that we’ll eventually uncover.
And then, there’s the question of numbers. It turns out that Pluto’s “home” has more dwarf planets than there are “classical” planets. There are five “official” dwarf planets and at least six other named dwarf planet candidates, plus another 400 or so objects that range from “nearly certainly dwarf planets” to “possibly dwarf planets” out in the Kuiper Belt and beyond.
That’s a HUGE number of dwarf planets. That makes the “classical planets” in the minority types in our solar system, doesn’t it? And, if you judge planets by their characteristics, then a LOT of planets in the solar system are icy, frozen bodies. Only a few are gaseous or solid rock. Kind of changes your perspective, doesn’t it?
Of course, numbers alone don’t make for planetary prominence. But, the fact that we do have so many planets that are in the dwarf planet category certainly does argue for that “continuum” idea I mentioned above. It also means that our solar system is even more complex and dynamic than we might expect if we only defined it as 8 planets, X number of dwarf planets, a bunch of comets, and jillions of asteroids.
It’s an amazing place, and that’s one of the central lessons that Pluto and the other dwarf planets are trying to teach us. So, let’s stop focusing on a silly manufactured “definition” controversy and pay attention to what the worlds of our solar system are dangling before our eyes. It’s something amazing! I promise!
