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A friend asked, "What's the point, what's the big deal about Pluto?". My answer is "It's about discovery, exploration, learning something new, going where no-one has gone before."
Pluto has nitrogen lakes, fossilized frozen records of past liquid flows, active flow patterns, land mass erosion, icebergs floating on a sea of nitrogen, it has volcanoes or geysers venting gasses, marsh lands, fissures, four moons moving erratically, its a binary planetary system with Charon and has an active geologic history that cries out for an explanation. I expected Pluto to be dead like our moon but instead it is geologically active. IT'S ALIVE, IT'S ALIVE!!!
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Before I jump into this subject, I want to express my respect and appreciation to Alan Stern for his compelling reasons as to why Pluto is a Planet. Who's Alan Stern, essentially he's NASA's top-ranking official for science leading the New Horizons team and played a key role in getting us to Pluto. Alan, said this about Pluto's demotion from planet status. "The New Horizons project [...] will not recognize the IAU's planet definition resolution of August 24, 2006. You rock Alan!
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The definition of planet set by the International Astronomical Union (IAU) states that, in the Solar System, a planet is a celestial body which:
Clearing the neighborhood is such an ambiguous statement it could mean anything. Objects like asteroids regularly impact planets hence their neighborhood is not clear. Pluto crosses Neptune's path does that make Neptune a non planet? Personally I like the definition provided by Runyon Stern and others. |
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A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has enough gravitation to be round due to hydrostatic equilibrium regardless of its orbital parameters.
Credits: NASA/Johns Hopkins University Applied Physics Laboratory/SW Research Institute
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In January 2006 NASA launched this Probe named New Horizons to study the Pluto Charon system. It took nearly 10 years to reach its destination.
During New Horizons' voyage, Pluto was demoted by the IAU to non planet status because of the discovery of Eris by Mike Brown. In July of 2015 New Horizons approached the Pluto/Charon system and the adventure of discovery began. The various components on New Horizons were designed to help achieve the following objectives. |
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The mission's science objectives are to
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Pluto/Charon
This is the Pluto/Charon system with four small moons. Pluto and Charon rotate around a point in space that lies outside Pluto referred to as their barycenter.
This makes them a binary planetary system, but more often than not Charon is referred to as a Pluto moon. 
The four small ice rock moons called Hydra, Kerberos, Nix and Styx orbit around the same gravitational point Pluto and Charon share.
Pluto is about two thirds the size of our moon with a radius of 1,189 km (diameter 2,379 km or 1,478 miles) and a density of 1.86 g/cm3. Density is really important as a density of 1 indicates water, greater than 1 means there's some rock mixed in with that water ice. |
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Charon's radius is 606 km (diameter=1,212 km or 753 miles) with a density of 1.702 g/cm3. Styx and Kerberos are about 6-12 miles (8-13 km) while Hydra and Nix are about 25-30 miles (40-48 km) in size.
Pluto's orbit
Pluto's orbit
Pluto has seasons as we do on Earth since it is tilted and migrates closer to and farther from the Sun. Pluto's orbit around the Sun takes 248 Earth years so each season last 40 and 80 years. Since Pluto is tilted and its orbit is eccentric (off center), its seasonal cycles are more complicated than simply dividing its orbit into four equal parts. As Pluto nears the Sun its orbit speed up, conversely it slows down at it farthest point known as its aphelion.
credit Emily Lakdawalla after Candy Hansen
Pluto was discovered in 1930 by Clyde Tombaugh, hence, it hasn't even made half an orbit around the Sun since its discovery.
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Some nomenclature
Ellipse = oval shape, Eccentric = off center, Ecliptic plane = imaginary plane created by the orbit of the Earth around the Sun, the Ecliptic plane is 7.25 degrees off the Suns equator, Perihelion = closest to the Sun, Aphelion = farthest from the Sun, If the eccentricity of an ellipse is close to 1 (like 0.8 or 0.9), the ellipse is long and skinny. If the eccentricity is close to zero, the ellipse is more like a circle. The eccentricity of Earth's orbit is very small, so Earth's orbit is nearly circular. Earth's orbital eccentricity is less than 0.02. The orbit of Pluto is the most eccentric of any planet in our Solar System. Pluto's orbital eccentricity is 0.2488 (Mercury = 0.205). |
image by Randy Russell
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Pluto's orbit around the Sun is inclined to the ecliptic plane by 17 degrees.
Pluto and Charon's polar axis is tilted 118 degrees relative to their orbital plane around the Sun. This means they spin backwards relative to their orbital direction of rotation, they have a retrograde spin. Any planet tilted on their axis more than 90 degrees is in a retrograde spin. The Earth as viewed from above the North Pole spins in a counter (anti) clockwise direction in line with its orbit rotation around the Sun as do most planets, Pluto, Venus and Uranus on the other hand spin in a clockwise direction. |
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Pluto Preflyby
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This was our best resolution image of Pluto taken by Hubble before New Horizons flew by this incredible system. It was later resolved to this image via computer algorithms. >>>>>>>>>> |
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Image Credit: NASA-JHUAPL-SwRI
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| pluto_high_resolution.jpg |
False Color Image Credit: NASA/JHUAPL/SwRI
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Water ice on Pluto is hard as rock and is the land and mountains. Gasses like nitrogen, methane and carbon monoxide which exist in our atmosphere in a gas state are frozen into various consistencies on Pluto that can produce glacial taffy like (toothpaste consistency) oceans, snow, fog or even liquids. The air we breath on Earth is 78% nitrogen while on Pluto it is an ocean of glacial paste (Sputnik Planitia). Pluto's temperature can range from 35 to 55 Kelvin as it migrates inward/outward to the Sun in its elliptical orbit.
Sputnik Planitia (SP) is a viscous slow flowing nitrogen mix of frozen gasses which are more dense than the frozen bedrock water ice in the area hence, the water ice will float atop the nitrogen. NASA has this to say about it. Even though water ice has a strong crystalline structure when frozen it expands and becomes less dense so it floats on the much softer fluid tooth paste denser nitrogen.
When I first wrote these pages I spoke as someone with conclusions and clear statements. The more I know the less sure I am about drawing absolute conclusions. Zone 1 above is a typical example. When I first created this page 1 3/4 years ago, I saw the icebergs as floating along troughs within an ocean of nitrogen.
At SP, I now see floating iceberg mountains, fluid running down from the eastern upland areas spilling into SP, fluid seeping up from below filling craters and low areas, fog condensing onto the upland mountain ranges, land masses collapsing, circular patterns created by outflow, bubbling warmer fluid welling up from below SP, flow patterns migrate west from the eastern uplands, south from the north western land, east from the western edge as well as south and snow falling from above. There's so much going on, its difficult to say one thing is creating any one particular effect. Some icebergs appear to be floating while others are grounded to bedrock some appear to be isolated while others are simply exposed land peaks covered by smooth fluid which appear to be icebergs but are more akin to islands.
Its an insanely complicated dynamic scene.
Sputnik Planitia (SP) is a viscous slow flowing nitrogen mix of frozen gasses which are more dense than the frozen bedrock water ice in the area hence, the water ice will float atop the nitrogen. NASA has this to say about it. Even though water ice has a strong crystalline structure when frozen it expands and becomes less dense so it floats on the much softer fluid tooth paste denser nitrogen.
When I first wrote these pages I spoke as someone with conclusions and clear statements. The more I know the less sure I am about drawing absolute conclusions. Zone 1 above is a typical example. When I first created this page 1 3/4 years ago, I saw the icebergs as floating along troughs within an ocean of nitrogen.
At SP, I now see floating iceberg mountains, fluid running down from the eastern upland areas spilling into SP, fluid seeping up from below filling craters and low areas, fog condensing onto the upland mountain ranges, land masses collapsing, circular patterns created by outflow, bubbling warmer fluid welling up from below SP, flow patterns migrate west from the eastern uplands, south from the north western land, east from the western edge as well as south and snow falling from above. There's so much going on, its difficult to say one thing is creating any one particular effect. Some icebergs appear to be floating while others are grounded to bedrock some appear to be isolated while others are simply exposed land peaks covered by smooth fluid which appear to be icebergs but are more akin to islands.
Its an insanely complicated dynamic scene.
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Zone 1
The smooth surface in this image is flowing viscous nitrogen which has large polygonal shaped cellular mounds bounded by troughs.
Scientists think these large blocks of ice are like icebergs floating on a sea of viscous frozen nitrogen. At the center of Sputnik Planitia there are no icebergs but as we move out toward the edges some strings of icebergs form in the nitrogen troughs and follow those troughs to the edges, The outer edges of the nitrogen flow seems to show either land which is collapsed and covered in smooth nitrogen appearing as icebergs or rocks organized into circular concentric rings reducing in size the further they are from land. |
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The nitrogen ocean creates an atmosphere or fog which is more dense at lower elevations this fog travels upwards into the uplands turning them into wetlands as the gasses are wrung out through a condensation effect known as an adiabatic lapse rate. As this gray fog condenses it coats the uplands and produces runoff.
In the above image clear signs of fluid flowing into SP creating circular rings can be seen this scene reminds me of the Horseshoe Falls at Niagara Falls. All of SP is a sunken basin bounded by walls of land ices about 2 miles high. Technically this means Sputnik is a Planitia not a Planum as a Planum is an elevated plain or plateau and a Planitia is a sunken plain but early on NASA was calling it a Planum so sometimes Sputnik Planitia is errantly referred to as a planum. |
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At Niagara, as the water flows over the elevated cliff face it erodes the base rock below causing the falls to retreat upstream this is likely what is taking place on Pluto at Zone 1.
The Grand Canyon in Arizona is about a mile deep and the temperature difference from top to bottom averages about 11 ºC (20 ºF), a similar type of temperature change occurs on Pluto. The temperature within the SP basin is warmer than at elevated zones.
The Grand Canyon in Arizona is about a mile deep and the temperature difference from top to bottom averages about 11 ºC (20 ºF), a similar type of temperature change occurs on Pluto. The temperature within the SP basin is warmer than at elevated zones.
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Zone 2
Originally I saw these two clumps as icebergs that floated up to and against the land ice forming clusters of small bergs primarily because of the umbilical cord that appears to connect them.
Now I see them more as land ice that has sunk along the edge of SP and is getting covered by the atmospheric moist gray fog. They are also likely dissolving somewhat in the warmer nitrogen fluid. It does appear as though there is an old layer of red tholin getting covered by a younger layer of atmospheric gray stuff. The red tholin develops slowly and accumulates as a sort of pollutant landing or developing on top of the surface. |
On Saturn's moon Titan. red tholins are developed in the atmosphere and so it is assumed this is what's happening on Pluto since it has an atmosphere. Charon doesn't have an atmosphere and hence theoretically not capable of creating its own tholin but as New Horizons flew past Pluto it turned to observe an object called 1994 JR1 and it is no larger than 30 miles doesn't have an atmosphere but is covered in red tholin as are many Classical Kuiper Belt Objects without atmosphere's so this obviously can't be a singular requirement for the presence of red tholins.
