Pluto is losing its atmosphere to solar wind, and it is forming an ionized tail behind it.
Correct. Then Hubble started to take imagry of Pluto showing that it had more of an atmosphere than it should have. The problem with that is that there is no, at least no known, way to pump energy into Pluto like there is with Europa, Enceladus, Titan, even the earth. So, where does the "air" come from?
the thing that has me shocked is that I was expecting a body like Ceres with a bit of Triton mixed in. But as we know, the joy of looking at something completely new is that you get a whole series of questions that you did not know about prior.
Why are there big dark spots on the side of Pluto facing Charon? What is that giant flat, smooth area that looks like a Heart? WHY ARE THERE NO CRATERS? I mean, wow, NO CRATERS! not even any big ones! If there was a giant impactor that split the proto-Pluto into the current Pluto system, should there not be some scars from that? Why is the atmosphere of Pluto bigger than expected? Pluto has ice caps! ICE CAPS! What is that giant dark spot on Charon's pole area?
It is going to take 20 months to get all this data back to earth, then it is going to take a year minimum to figure out what the heck we are looking at. So at least a half-decade of questions and hopefully answers about this place. My big BIG hope is that Pluto is so weird that it fuels the desire for the Neptune Orbiter; Triton is about the same size as Pluto and we think it is a captured Plutino object. I doubt we will go back to Pluto anytime in my lifetime and an orbiter will take 20 years to get there anyway so what we have now is all we are going to get. But Neptune is doable in the near future.
TLDR: Space is awesome.
Sure. Europa has a liquid ocean of water under its ice. But Europa is small and should be frozen solid. So you need a source of energy to melt that water ice. It turns out that the tug of gravity from Jupiter, Io and Ganymede create tides in Europa that pull and tug on it; this generates energy as the internals flex and rub up against itself. In the earth, the moon, creates tides that we see at the ocean, but it also creates tides in the earth itself, some 2-3 feet at the equator. Enceladus has a pool of liquid that is heated from the push and pull of the gravitational tug of war between Saturn and Titan.
Pluto, however, has no source of tidal energy input. Pluto and Charon are in a gravitational equilibrium; there is no tug of gravity inputting energy into either body, or at least there does not appear to be. Because Pluto and Charon are tidally locked to each other both in revolution and rotation, there is no push-pull like in the other small bodies listed above.
So, why is there so much gas above the surface of Pluto? Where did it come from? Why is the surface of Pluto so young and crater free?
And yea, this excites me. I've seen Pluto with my own eyes through a 25" telescope as nothing more than a very faint dot that barely moved over two nights. Now, that dot is a whole world with strange geology. I'm going to do an outreach event tonight showing 200-300 people Saturn, and I expect a lot of Pluto questions as well.
- Because Pluto and Charon are tidally locked to each other both in revolution and rotation, there is no push-pull like in the other small bodies listed above.
Ahhh! I did not know this. That does make it interesting. Thank you.
- I've seen Pluto with my own eyes through a 25" telescope as nothing more than a very faint dot that barely moved over two nights.
I had a 10" Dobsonian back in the day; I looked into the logistics of looking at Pluto and decided that it was well beyond my means. I think the biggest glass I've ever looked through was a 20". So this begs the question - what do you do and where do you do it? because about the only regret I have in moving from New Mexico to Washington was the lack of easy deep sky...
I moved from the California desert to the Ohio Valley. Every time there is something to look at in the sky I debate moving back west, then the bills come due and I am glad that I am here. There is something to be said for a $350 mortgage payment that all the clear dark sky in the world can't overcome.
Our Astronomy Society does a lot of outreach trying to keep membership up enough to fund the fun stuff we like to do. We own 40 acres out about an hour away from town that is dark enough to see M13, M3 and M31 with the naked eye on good nights. The bad news is that the last year or so has been the worst weather wise in 12 years I have been out here. We are right under the jet stream, its hot as ass and twice as humid. When it gets a bit cooler and starts getting dark at 8PM again I do stuff with the library as well.
As for where, I have an agreement with the city and two different grocery stores that I can set up my scope and let people look. Tonight I am going to set up in a city park and hope for clear enough skies to get a few hundred people a chance to look at Saturn. The moon is too close to the sun to let randoms look through the scope, but next week will be first quarter and that will be a big draw during the day and we can hit 1000 people a day looking through a scope. Out of those 1000, 100 will take a flier, 20 will contact the facebook group and 1 or two will send messages about either "hey come to our school!" or will actually join the club. But I get to talk about space and nerd out for a few hours, so that makes me happy.
Pluto is considered a "challenging" object for anything under a 12" scope. If you have a camera and a good mount, a 4" scope can get an image, assuming you know what you are doing. There is a group of people who have been able to visually observe Charon! They were in the mountains, over 9000 feet above sea level and using 36" dobsonians, but they were able to watch Charon revolve around Pluto over a week. This is one of those things where knowing that the object exists helps you more than you care to admit.
I'm going to a star party in West Virginia next month in the shadow of the NRAO and get to go on a full site tour. but damn if I don't miss star gazing at 8500 feet in the Sierras. That was an experience that everyone needs to do at least once.
Although they are tidally locked, that estimate is at first order. How much energy do higher order instabilities contribute to energy generation? Is it something sufficient to keep in motion something that has been previously set?
That is an interesting question I did not think of before. I guess that depends on how long ago Pluto and Charon became tidally locked. When I see Dr. Harold Geller next month I'll ask that question. Maybe we will have more data and can at least start to guess.
I cant wait to hear more results from the data!
Also, could you elaborate on why you think that ice caps are so surprising? Pluto has an atmosphere that is in equilibrium with the ices on the surface, so it would redeposit these ices on the surface. More ice would be deposited towards the poles since they are the coldest areas. Also, more ice will sublimate in the warmer areas near the equator. Pluto is very far from the sun, so these differences shouldn't be too pronounced, but as you can see they are not.. It is possible however that there is something else that I'm not considering that would make Pluto unlikely to have ice caps.
Damn it Hubski, I have to go outside! Why are the polar caps surprising? Pluto is like Uranus in that the poles are in its orbital plane. I honestly did not expect polar caps for that reason. If anything, the pole that is lit up by the sun, I anticipated to have less ices on it, and a stronger methane and carbon monoxide signature in the shadowed part of the body.
We already expected there to be methane and CO ices on the surface, but in an actual polar cap in the part of the globe in constant sunlight was something neat to see.
Why would you want to go outside, when inside is where all of the cool space stuff is?
Pluto does rotate on its side, but its pole isn't (currently) always facing the sun. In fact, the sun is currently mostly heating the equator. Here is its current orientation, and more details.
Very nice! I live in Orlando and am involved with an Astronomy Society here. We have a few 8" telescopes and one 21" (in the Robinson Observatory). I know your pain of trying to cut through light pollution (damn Disney) and humidity and poor conditions. Have fun with all of that!
We sat outside as long as we could stand it. not nearly the crowd we usually pull in but 200+ anyway. I try to hit the public the week around first quarter as I can have the scopes up and looking at the moon for a few hours before sunset and hype Saturn at nightfall (9:30PM up here).
We dodged clouds all evening but managed to get Saturn at 200x for most of the evening. That is good enough to see 4-5 moons and the Cassini division. And there was a ton of Pluto talk.
Next outreach I have to bring my globes to explain how big Pluto, the moon and the earth are.
- If there was a giant impactor that split the proto-Pluto into the current Pluto system, should there not be some scars from that?
No. Not necessarily.
Pluto has a very active geology. It is very possible that this event happened long enough in the past that all evidence has been wiped away, or covered by the deposition of ices from its atmosphere.
EDIT: This active geology is also why we see so few craters.
- Pluto has a very active geology. It is very possible that this event happened long enough in the past that all evidence has been wiped away, or covered by the deposition of ices from its atmosphere.
Was anyone expecting an active geology? I read that some people were expecting a dead, more cratered Triton, but the lack of craters seems to have taken everyone by surprise.
And yes atmosphere is being mentioned, and that can be a factor, but we are talking thinner than the Martian atmosphere here. Pluto is tiny, roughly 1/2 the diameter of the moon, and this preliminary data is showing it acting more like a comet than a planet. Can an atmosphere that thin erase that much geology? Or does Pluto get close enough to the sun every 200 years to melt the surface enough to reform the surface?
- Was anyone expecting an active geology?
There was a little bit of speculation because of the atmosphere that was detected by the Hubble, but largely, no. That idea was mostly ignored because we weren't sure what could CAUSE an active geology on an object as small as Pluto.
- And yes atmosphere is being mentioned, and that can be a factor, but we are talking thinner than the Martian atmosphere here.
Yes, Pluto's atmosphere is incredibly thin, but something to remember is that while on something like Mars, the only means of the atmosphere destroying evidence of craters is erosive factors like wind, on Pluto the atmosphere is also in equilibrium with the ices on the surface. Ice will "frost" out of the atmosphere and blanket the surface, covering up a lot of features. The ice is melting more on the parts that face the sun and depositing more on the parts that are not. This difference isn't a lot, but it's enough to add up over time. Pluto is also, as you mentioned in your previous post, orbiting "on its side", which means that this deposited ice is melted off of the summer side and redeposited on the winter side over and over for each orbital period. This type of cycling could easily cover up evidence of craters.
- this preliminary data is showing it acting more like a comet than a planet.
This was expected. Compositionally, Pluto IS a comet, just a very large one. The tail was expected when we saw that the atmosphere was so large. We expected its atmosphere to be in the process of being depleted. The tail always points away from the sun, so we couldn't have detected it until we got behind it, this is just confirmation.
why 20 years? is it because you are imagining a complete redesign of the mission? Perhaps a little rover? How I wish we had one in every large object in the solar system.
- why 20 years?
Way back in 2003 there was a plan for a Pluto orbiter and "hopper" lander. The trip out to Pluto was going to be 14-16 years depending on the launch window. So, 2-3 years to build the thing, then launch, then get there, then deal with the data transfer back home assuming all goes well. This is where I got the 20 years from. And if we are going to go back to Pluto, IMO, we should go to orbit and land, stay a while, and push our abilities to the limit.
Link to the idea for the mission is here but they could not get the funding, and got New Horizons pushed through instead.
For those curious, this hypothetical mission would take longer to get to Pluto than New Horizons because it wouldn't just be flying by, it would need time to set up a slower approach and enter into orbit around Pluto and give the lander time to collect the sample.
It would also need enough fuel to then change trajectories and return to Earth, as well as all of the fuel for the lander. These types of sample return missions are very expensive, which is why there have not been many. There were a few somewhat famous ones to the moon in the 60s and 70s, one that collected solar wind particles (barely had to leave the Earth's neighborhood, no landing required), one that flew through the tail of a comet and collected dust (no landing required), and one by JAXA that retrieved a sample from an asteroid. It's ultimately cheaper to bring the science/instrumentation to the object than the other way around, and those are the types of missions that get funding.
A rover is far more likely than a sample return mission, but even so I wouldn't put money on a return to Pluto in the very near future.
And we don't have the plutonium for the power anymore due to nuclear arms limitations.
And investing a 30 year career into one mission is much to ask of a scientist.
And if you don't make the mission an international treaty with concrete spending and mission statements, the congress 10 years out will cut your mission funding.
And and and... sigh,
It can be done if we have the will. But that is the case in most things, is it not? Also that Hauyabusa mission is a study is disaster engineering. Everything that could go wrong at some point did, yet they still were able to hit the earth's atmosphere and land in Australia, albeit a bit later than planned. This is the mission that the idea of "Never give up! Never Surrender!" was a real battle cry. And now they are trying to rescue the Venus orbiter with seat of the pants engineering as well. I feel bad that JAXA has had a string of bad luck, but watching them recover has been amazing.
Well, you need someone like Alan Stern. He invested his whole career into New Horizons and he is pretty much the only reason why it happened and became the success that it is and has been so far.
You know, his son Jordan is about to start grad school... Unfortunately I don't think that he's up for following in his father's footsteps. He's a math major in undergrad rather than anything astronomy related. Understandable that he wanted the chance to prove himself on his own rather than live in his father's shadow.
But my point is that we need someone with that kind of drive and determination to get a mission through. The type of person where no matter what happens they keep trying until they finish the job. Maybe whoever was in charge of the Hayabusa?
Dammit! I leave for lunch and all of this discussion happens.
francopoli did a very good job of answering your question, but there is one thing that I'd like to clarify.
Pluto swinging inside the orbit of Neptune would not bring it close enough to the sun to outgas significantly enough to cause the atmosphere that we are seeing today. This is the mystery of "what heated up Pluto and caused these gasses to sublimate" that francopoli was talking about in his posts. It didn't get close enough to the sun, so what heated it up? As he pointed out, it isn't tidal interactions with another large body, the usual other source of heating in our solar system.
And to expand on this mystery:
1. Pluto has an atmosphere that should have been stripped away by now by the solar wind. This is what is currently happening to it and is creating the tail. The question is, what is replenishing it?
2. Pluto, like any other comet, is full of ices which sublimate into gasses when heated. This is what causes the atmospheres and the tails on comets that venture closer to the sun. This is where that gas is coming from, the question is, what's heating the planet?
The three common, go-to sources of heat in a body in our solarsystem are
1. The sun (Pluto is too far away)
2. Tidal forces (Pluto is already tidally locked to Charon, francopoli gave a good description of this)
3. Latent heat of formation (Pluto isn't big enough for this to have stuck around. Source: Mercury's has not stuck around, and it is bigger than Pluto).
So what's causing this heat? Well first here are some other facts that I'd like you to consider:
With all comets, as the ices sublimate off, they leave the rock behind. With smaller comets, this rock is left behind in an almost "haphazard" fashion. The rock stays where it was, and it might roll a bit downhill towards the comet's center of mass. This leads them to be to porous and misshapen (like 67P).
----Leaving facts behind, entering speculation. Everything below here is an educated guess from someone who has never studied Pluto in particular, but has taken graduate level Planetary Science classes, including (recently) one in geophysics (the relevant subject here). It is very possible that I think that I know more than I do, so take everything below with a grain of salt----
My thoughts/hypothesis/speculation that might be completely wrong (feel free to NOT read this, it might be wrong)?
I think that there is something special about Pluto that we haven't seen with other large bodies that makes it take longer to lose its latent heat. And that special thing is its composition and size. The only other object similar to it in both of these respects is Triton, but Triton has tidal heating that might mask this effect.
Remember how the other comets are misshapen and porous? Well, Pluto is big enough to pull itself back into a spherical shape (hydrostatic equilibrium). Its gravity is strong enough to pull the rocks back down and close up these porous "gaps" left by the escaping volatiles.
Perhaps some event (possibly an impact) imparted a lot of heat into Pluto in the somewhat recent past and caused a lot of ices to sublimate all at once, and now the atmosphere is slowly returning to equilibrium. As Pluto reforms itself into a spherical shape, it would create all sorts of active geology like mountains and canyons and other things that we are seeing there that we weren't expecting. This active geology would also cover up the scars of this event, much like what happens on the Earth, or possibly by the refreezing of these gasses, creating an ice layer that would hide the craters.
This isn't too unreasonable. While the Earth has plate tectonics and thus is only geologically active along faults and at hot spot volcanoes, this would be happening to Pluto everywhere, and the surface rock would be being reformed everywhere, because all of Pluto would have been outgassing and all of Pluto would now be compressing.
(CAUTION: EXTREME SPECULATION IN THIS PARAGRAPH) Perhaps the "heart" is the impact site, and the heat from impact melted a lot of the ices and created a muddy crater that had a low enough viscosity to flow into becoming flat again (no crater), and even flow some mud into the surrounding areas. I would suspect that the original impact crater was MUCH MUCH smaller than the heart, and the rest of the heart would be caused by this mud flowing out. We already know that this region resembles frozen mud cracks on the Earth, and is rich in Carbon Monoxide. This would fit with liquid Carbon Monoxide mixing with the rocks and dirt on the surface and creating a mud that then refroze. In fact, this feature is so consistent with a freezing mud flow, that I would personally be surprised if it wasn't caused by some sort of local heating, causing what I just described.
The hypothesis that I just described fills in a lot of the gaps in knowledge and questions that we currently have about Pluto, BUT keep in mind that I am by no means a Pluto expert. There are definitely things about Pluto that people have studied and that the experts know about that I do not, and it is also very possible that one of those things could throw my whole hypothesis out of the window. I'm mostly just typing this out so that I have a record of what I thought "way back when", so that I can objectively see how right I was later on, and as "food for thought" for you guys. Again, it may all be wrong, so take it with a grain of salt.
- I think that there is something special about Pluto that we haven't seen with other large bodies that makes it take longer to lose its latent heat. And that special thing is its composition and size. The only other object similar to it in both of these respects is Triton, but Triton has tidal heating that might mask this effect.
Now, wouldn't THAT be a neat thing to find out! Triton is an interesting object that I hope we get a better look at during my lifetime. It is most likely a captured object, orbiting the "wrong way" around Neptune. It is (barely) bigger than Pluto as well.
This is why I love science. Last month, we did not even know to ask these questions, yet here we are excited and forced to think outside of a comfort zone. Maybe something odd is going on in the Pluto system! Or maybe the impactor that created the Pluto system was recent! Or maybe there is a weird new chemistry going on here! Maybe a bit of everything?
I've been reading up a bit on a proposed sample Return Mission to Pluto. 12 years to get there, a few years to map the place out and possibly make fuel on the surface of Pluto, and due to the small size and weaker gravity maybe multiple landings. Then take off and head back to earth in 12-13 years. I really hope that Pluto turns out to be fantastically weird so that something like this mission becomes a reality.
- I'm mostly just typing this out so that I have a record of what I thought "way back when", so that I can objectively see how right I was later on, and as "food for thought" for you guys. Again, it may all be wrong, so take it with a grain of salt.
I'm doing the same thing here. It will be neat to come back to this thread a year from now when we have most of not all the data and can laugh at how wrong/right we are.
I have to leave, but want this here to get a reply if you have time today. I'll try to answer more replies Sunday and apologize in advance if I don't get back to you quickly.
- Remember how the other comets are misshapen and porous? Well, Pluto is big enough to pull itself back into a spherical shape (hydrostatic equilibrium). Its gravity is strong enough to pull the rocks back down and close up these porous "gaps" left by the escaping volatiles.
Mimas is the smallest body in the solar system know to be in hydrostatic equilibrium. Mimas is 200 miles in diameter. Pluto is nearly five times larger. Pluto's density does not suggest that it is porous like a comet or asteroid. Ceres is the closest analog I was expecting and Pluto is over two times as wide.
Something is reforming the surface of Pluto! This is something that I was not anticipating at all, and it brings up a multitude of possibilities. Here is hoping that the next two years will answer some questions.
- Pluto's density does not suggest that it is porous like a comet or asteroid.
Nope, because its gravity is pulling it together enough to compress the rocks together and make it not porous. This is the point that I was trying to make, sorry if it wasn't clear.
You get to a point size-wise where eventually you stop just getting bigger, and you start getting denser. This happens when the force of gravity overcomes a force stopping things from compressing. There are many such forces, and thus many such points where "object gets bigger, then starts getting denser, then starts getting bigger again, then denser again, etc" as you add more and more mass.
- Something is reforming the surface of Pluto!
Again! Speculation on my part! Take it with a grain of salt! Please don't use concrete language like "is" or else I'll regret posting my thoughts and will take them down so that people don't get confused.
Those aren't facts, that's a hypothesis from me.
dont take them down. i think the warning suffices.
- You get to a point size-wise where eventually you stop just getting bigger, and you start getting denser. This happens when the force of gravity overcomes a force stopping things from compressing. There are many such forces, and thus many such points where "object gets bigger, then starts getting denser, then starts getting bigger again, then denser again, etc" as you add more and more mass.
I thought that was what you were saying. This is something neat to point out to people. Jupiter and Saturn are not that different in size; Saturn is 9.5 earths wide and Jupiter is 11.2 earths wide. If you could find three more Jupiters and dump them into our current gas giant, the resulting planet would be SMALLER than the current one! Jupiter size objects don't really start to get bigger until they start fusing deuterium and become brown/red dwarfs.
- Again! Speculation on my part! Take it with a grain of salt! Please don't use concrete language like "is" or else I'll regret posting my thoughts and will take them down so that people don't get confused.
Yea, I'm jumping the gun here. Here is why I said that with certainty, and thank you for making me defend such a definitive statement. We have six "young" surfaces in the explored solar system. Venus, which looks like the whole planet resurfaces itself every few million years, which along with raining METAL and having a surface that can melt lead just adds to the weirdness factor. You have the Earth which resurfaces itself due to tectonic plates moving, water erosion, wind and biology. The impact that finished off the dinosaurs is 200 miles wide, yet was not discovered until the 1980's due to it being eroded away at the surface. Then you have Io and Europa. Io was until this month the youngest surface in the solar system. Io is also the most volcanic body in the solar system. Europa has resurfaced itself "recently" as in the last few 100 million years. Enceladus has a young surface where the geysers are spewing water ice back onto the surface of the moon, and Titan has active weather that is at least masking the age of the surface.
All of these ages are mostly determined by crater counts.
To not see any craters on Pluto was a shock to me. I was expecting a mix of Triton with its ice geysers and Ceres with its heavily craters surface. The "easy" answer is that there is a mechanic like we have already seen in the solar system reworking the surface. I hope that the real answer is something more odd and interesting!
Is it the case that there are absolutely no craters on Pluto? or is that our best estimate from the particular locations we saw in the media release?
Seems that there are a few in the new images. This is the border of the smooth white area and the darker spots. This reminds me a lot of Iapetus. You can clearly see impact craters at the edges of the "white" area. There is also a larger crater that looks very similar to a lunar maria with a flooded floor.
So my initial guess that there is something on Pluto that is causing it to resurface itself may be at least partially correct. Neat.