SPACE

[zip accident]

I can’t imagine there’s glaciation, as in flowing glaciers. That would require precipitation, and so a proper atmosphere, which if it had it lost long ago.

No, Pluto does have an atmoshpere:

https://en.wikipedia.org/wiki/Pluto#Atmosphere

in 1987, the north pole of Pluto came out of the shadow for the first time in 120 years, causing extra nitrogen to start sublimating from the polar region. It will take decades for this nitrogen to condense out of the atmosphere as it freezes onto Pluto's now continuously dark south pole.

So the snow is nitrogen snow.

[pogo]

But not much of one:

The surface pressure ranges from 6.5 to 24 μbar (0.65 to 2.4 Pa),[122] roughly one million to 100,000 times less than Earth's atmospheric pressure.

It’s not a normal permanent atmosphere: Pluto’s gravity isn’t strong enough to hold one, just as ours isn’t strong enough to hold on to hydrogen and helium, the two lightest elements (Hydrogen forms compounds most notably with oxygen so is plentiful. But helium the second most common element in the universe hardly exists on Earth. It was first discovered by astronomers looking at the Sun. Hence its name, from the Greek for Sun).

What is happening is it is getting just enough sunlight to sublimate, i.e. vaporise [Nitrogen] ice straight into gas, in very small quantities. This varies over time, hence the varying pressure. At other times it is further from the sun, or that end is not facing the sun, so the gas can solidify again. This will evolve over time. Over many cycles of taking the top surface off bits of ice and re-applying it the surface should get smoother with more rounded edges. I don’t know if that’s visible in the last image I posted.

But not glaciers, i.e. snow building up enough to make ice flow.

[zip accident]

But not much of one:

The surface pressure ranges from 6.5 to 24 μbar (0.65 to 2.4 Pa),[122] roughly one million to 100,000 times less than Earth's atmospheric pressure.

It’s not a normal permanent atmosphere: Pluto’s gravity isn’t strong enough to hold one, just as ours isn’t strong enough to hold on to hydrogen and helium, the two lightest elements (Hydrogen forms compounds most notably with oxygen so is plentiful. But helium the second most common element in the universe hardly exists on Earth. It was first discovered by astronomers looking at the Sun. Hence its name, from the Greek for Sun).

What is happening is it is getting just enough sunlight to sublimate, i.e. vaporise [Nitrogen] ice straight into gas, in very small quantities. This varies over time, hence the varying pressure. At other times it is further from the sun, or that end is not facing the sun, so the gas can solidify again. This will evolve over time. Over many cycles of taking the top surface off bits of ice and re-applying it the surface should get smoother with more rounded edges. I don’t know if that’s visible in the last image I posted.

But not glaciers, i.e. snow building up enough to make ice flow.

It's not a NItrogen - Oxygen atmosphere like Earth's, but it is an atmosphere, it was known that it existed before New Horizons arrived, they thought it might be deep enough to make the solid surface lower than Eris's, but it turns out Pluto is bigger but less dense than expected. I suspect it is permanent, but permanently in flux, as ours is. Temperature will be significant, some gases last as gases down to low degrees kelvin, so with so little temperature at Pluto, they will still be gases, but won't have the energy to escape the system, even though it's not that massive. Interestingly, our Moon, which is bigger but mostly hotter has a lot less atmosphere.

It might be right to describe Pluto as a small cold gas giant.

[Muttley]

Interesting...

NASA Has A "Huge Announcement" To Make...

...NASA is set to announce the major discovery of a new planet by the Kepler Space Telescope tomorrow (July 23) at noon EDT (5 p.m. BST).

http://www.iflscience.com/nasa-announce ... ch-it-live

Going live now: http://www.nasa.gov/news/media/newsaudio/index.html

[zip accident]

Going live now: http://www.nasa.gov/news/media/newsaudio/index.html

An earth twin but twice the gravity? Venus is a better match by far.

[pogo]

Sort of lost interest in the planet searching, in that it all seems a bit meh. I’m sure they’ll find something Earth sized the right distance from a star sooner or later. Then many more. Time is on their side, in that they have only a few years data and the more data you have of small variations in star light the more planets you will find.

Problem is it seems planets are exceedingly common. So much so that pick a star at random and it might well have a planet that could support life. Lots and lots of planetary systems, much like ours. It makes sense as the same conditions, the same mix of elements would have been available to stars forming about the same time in this region of space.

But we don’t have any way of finding out more about them. we may one day be able to image distant planets directly but they will likely be the largest brightest ones, the “hot Jupiters” orbiting very close to their star, the ones most unlike our own system. But others? I don’t know if that will ever be possible. We have a hard enough time imaging the smaller rocks in our own solar system, never mind those tens of light years away.

[gumboot]

What are the odds of a planet actually passing between us and its local star, anyway? They can't be high, so if that's the only way they're being found then there must be a heck of a lot more than that that won't be discovered until another technique becomes viable.

[pogo]

It’s not the only way to find them. Another way is to look at the wobble induced by the gravitational pull of planets. This can tell us much more as we can deduce the orbits and masses or multiple planets from one set of data. It’s not much use for Earth sized planets, but in theory could detect planets very far away.

Yet other way is directly imaging them. This in theory can tell us much more as with light from a planet we can deduce things about its composition, or at least its surface. But it only works with the closest stars and largest planets.

Neither of these depends on viewing the other system edge on. Together with occlusion its quite a toolkit of methods for looking for planets around other stars. And all of these methods are still in their infancy. They all depend on looking closely at vastly remote stars, which would benefit greatly from more and better space-based observatories going up.

[Dio]

What are the odds of a planet actually passing between us and its local star, anyway? They can't be high, so if that's the only way they're being found then there must be a heck of a lot more than that that won't be discovered until another technique becomes viable.

Having the right planar alignment is in the 5% range IIRC.

[Darkflame]

I think the biggest impact finding a earth like planet can have is physiological.
Just a few decades back we were alone and special. Not a single extra-solar planet confirmed, and even a few theory's that we were "so unique" and our system must have been a freak event.
Now theres planets everywhere. Probably habitable zone planets everywhere too.
The idea that (on a geological level at least) we are a special case will probably die.

And if, which I think is quite plausible, we detect the light from a planet a few thousand light years away, and it shows a similar chemical make-up to earth as well, we have to start asking more questions about life elsewhere. Maybe revisit that drake equation with the newly known variables to see whats the mostly likely reasons for lack of intelligent life contacting us. Are we just "out of sycn" - missing their existence by long history. Do we get a warning that most intelligent species must wipe themselves out?
Or is the universe teaming with intelligent life, but the long distances meaning you need to "listen" very hard for it.

Most of all the finding other earth like planets kinda gives us no excuses. The universe is a big, cold, ridiculously hard place to get around in. But not impossible. There is other places for our species to go. We are not doomed with this star. In other words, there's no one to blame but ourselves when we die out.

[pogo]

I think that has already happened in a way, as statistically the chance that there’s life out there is effectively certain, under any reasonable assumptions. I mean if you assume that there’s 1/1000 chance of a star having an earth-like planet, and that there’s a 1/1000 chance life evolves on such a planet, then life has evolved on hundreds of thousands of planets in our galaxy. One of of over 100 billion galaxies in the universe.

And most people think those numbers are much higher. We now now that planetary systems are common. Many if not most will contain Earth-like planets, which we will continue to get better at detecting. And there’s no reason to think life isn’t common, maybe near certain under the right conditions and given enough time.

But it doesn’t help us much to detect such planets, even very close astronomically, as we cannot visit them. New Horizons show the limit of our ability to send things long distances. To reach the nearest star would mean going over eight thousand times as far, taking about 80,000 years at the same speed. We can look for radio signals, but they they might only be sent by civilisations, which might be very rare or transient, or even not interested in interstellar communication.

[F-ZeroOne]

Also worth pointing out thats its still not entirely certain that there isn't life, although almost certainly not intelligent [1], elsewhere in our solar system.

[1] Unless God has her holiday villa on Planet X or something...

[pogo]

Well, yes. Some of it is speculative but it’s hard to dismiss the possibility that Mars, Venus, the moons of Jupiter and Saturn might once or might even still have some form of life. If that is confirmed it essentially shows we are not that special at all, life can arise pretty much anywhere given time and the right materials.

More Pluto. Another image, a little photoshopped but the best view yet of the planet as a whole.

[pogo]

Pluto from the far side, with the atmosphere backlit by sunlight

http://www.nasa.gov/press-release/nasa- ... e-on-pluto

[Darkflame]

Utterly beautiful stuff and fascinating. Trying to tease meanings from pixels gathered so far away.
I wonder if these are the most valuable pixels ever

New Horizons show the limit of our ability to send things long distances.

I think thats more to do with the resources our civilizations willing to put into it though. We have C as a apparently hard limit, but we are no where close to that so at the moment our speeds are more effectively limited by budgets, as well as the difficulty just getting stuff out of earths gravity well (thus limiting weight carried etc).
I'm still pretty convinced if you chucked a few trillion at the problem we could have probes going at 25% of C without too much issue. Presumably with externally supplied momentum, either via solar sails and a lazer, or some sort of array of satellites around the sun each giving it a little magnetic push as it goes past.
Both those solutions would be re-usable too. Although in the second you would have to alternate the direction you send things around the array so compensate for the momentum they gained the last time.
Or solutions we haven't thought of.
Maybe if we had a image of a earth like world we would be more keen to try things.