14 Jul 15
1 edit
Originally posted by sonhouseThere are several other known bodies of similar size and probably a number not yet discovered, yet there are not many people pushing for them to be called planets. If anything the resistance to them being called planets is what got Pluto demoted.
It's still pretty dam big! You certainly could not launch yourself off into space just by jumping up like you could on that comet they tagged with the probe.
It also must be mentioned that the giant planets are so significantly bigger than the rest that we really should treat them differently too.
We should stop thinking of the 'nine planets' (or eight) and instead think:
2 Gas giants
2 Ice giants
5 Rocky planets
multiple dwarf planets (I don't know how many)
many comets
many asteroids
space dust.
And then there are all the moons of the above bodies
And then there are all the objects around other stars.
14 Jul 15
Originally posted by twhiteheadAnd all that is dwarfed by the dark matter in the universe which outdoes the normal stuff we can see by 20 to 1 or so.
There are several other known bodies of similar size and probably a number not yet discovered, yet there are not many people pushing for them to be called planets. If anything the resistance to them being called planets is what got Pluto demoted.
It also must be mentioned that the giant planets are so significantly bigger than the rest that we really s ...[text shortened]... re are all the moons of the above bodies
And then there are all the objects around other stars.
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15 Jul 15
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Originally posted by vivifyActually no, the sun at the distance is still brighter than a full moon, light enough to read.
How are these pictures taken, since it should be pitch black given its distance from the sun?
Nasa's recently been doing a thing where it will tell you [weather conditions permitting]
what time of day [morning and evening] will the conditions be right to experience the light
conditions you would find on Pluto at midday. [kinda]
http://solarsystem.nasa.gov/plutotime/
Specifically as Pluto is currently about ~31au away, the sun is 1/(31^2) or ~~1/900 times
as bright as it is at Earth.
Given the sensitivity of the instruments on these satellites.
Heck, they scheduled observations of Pluto's far night/dark side using reflected light from
it's moon after passing closest approach.
EDIT: the full midday sun on the Earth has a brightness of ~32,000 - ~100,000 lux
Which means at Pluto that drops to ~35 ~110 lux Or the equivalent of a very dark overcast day
https://en.wikipedia.org/wiki/Lux
http://www.greenbusinesslight.com/page/119/lux-lumens-and-watts
15 Jul 15
I came across this:
http://www.bbc.com/news/science-environment-33531811
Nasa's administrator Charles Bolden said: "With this mission, we have visited every single planet in the Solar System."
Clearly even some in NASA are not ready for the 'dwarf planet' category.
Eris, a dwarf planet more massive than Pluto (although very slightly smaller) has not been visited.
15 Jul 15
Originally posted by twhiteheadhttp://apod.nasa.gov/apod/ap150715.html
I came across this:
http://www.bbc.com/news/science-environment-33531811Nasa's administrator Charles Bolden said: "With this mission, we have visited every single planet in the Solar System."
Clearly even some in NASA are not ready for the 'dwarf planet' category.
Eris, a dwarf planet more massive than Pluto (although very slightly smaller) has not been visited.
The latest and greatest so far, Horizon is now sending back super high res pictures, all went well with the flyby.
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17 Jul 15
Originally posted by whodeyReally, So far what I have seen have been labelled as water ice mountains... Which while very hard
Very interesting.
There seems to be a lot of rocks on Pluto.
Well I was not expecting this at all!! ðŸ˜
are not in fact rocks.
They are interesting as Pluto has a [thin] atmosphere which is made up of mainly nitrogen which is
constantly being blasted off into space by solar wind. The atmosphere is replenished by more
nitrogen ice subliming and turning into gas.
However nitrogen ice is weak and cannot produce mountains like the ones we have just discovered,
which means that those mountains must be made of something stronger, like water ice.
However this means that the nitrogen ice on the surface can only be a [relatively] thin layer, which means
that if it were not being replenished it should have evaporated off by now, which means that Pluto must have
recent geological activity [cryo-volcanos for example] that brought more nitrogen ice to the surface.
This is born out by the lack of visible impact craters, indicating a young surface.
This is interesting because we didn't know such activity could sustain itself for so long after the formation of
the [object] as all other examples of such icy bodies are moons closely orbiting gas giants that cause
tidal heating that explained the geological activity.
Pluto is nowhere near a gas giant and the closest thing to it is too small to cause enough heating and is
tidally locked anyway.
So we have already discovered new things about Pluto that tell us about the workings of the solar system
and we only just started.
17 Jul 15
Originally posted by googlefudgeIce and nitrogen?
Really, So far what I have seen have been labelled as water ice mountains... Which while very hard
are not in fact rocks.
They are interesting as Pluto has a [thin] atmosphere which is made up of mainly nitrogen which is
constantly being blasted off into space by solar wind. The atmosphere is replenished by more
nitrogen ice subliming and turnin ...[text shortened]... ings about Pluto that tell us about the workings of the solar system
and we only just started.
Well it's nice to know there is more than just rocks.
17 Jul 15
Originally posted by googlefudgeWhat would be the source of the nitrogen? Nitrides in buried rocks? Not sure.
Really, So far what I have seen have been labelled as water ice mountains... Which while very hard
are not in fact rocks.
They are interesting as Pluto has a [thin] atmosphere which is made up of mainly nitrogen which is
constantly being blasted off into space by solar wind. The atmosphere is replenished by more
nitrogen ice subliming and turnin ...[text shortened]... ings about Pluto that tell us about the workings of the solar system
and we only just started.