800 thousand years ago rivers and lakes could exist on Pluto

True, it was not water, but liquid nitrogen.



Now the probe New Horizons is already at a distance of 300 million kilometers from Pluto, while continuing to transmit valuable information about the planetoid. A number of data sent by the apparatus quite recently may be evidence of the existence of rivers and lakes from liquid nitrogen many years ago on the surface of Pluto.
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These data are photos of the surface of Pluto (high resolution photo), plus some data on a planetoid orbit. So, the network of "channels" that are visible on some photos of the surface of Pluto, most likely created by the flowing rivers of liquid nitrogen. Nitrogen ice still lies on the surface, including the already mentioned “channels” and former lakes.

“We see something that may well be an ancient lake,” says Alan Stern, one of the members of the New Horizons team. "This is a very flat place, because liquid nitrogen, which was at a certain level, has frozen here," the scientist comments on the situation. According to him, it is rather difficult to propose a different model that would explain modern morphology. But why now everything is frozen on Pluto, and how could the planetoid climate once be so warm that liquid nitrogen could exist on the surface? It's all about the unusual rotation of Pluto.

Now the axis of proper rotation of Pluto is at an angle of 120 degrees to the plane of the planetoid orbit. At Earth, this figure is 23 degrees. For Pluto, this position means the predominance of the tropical climate. About 800,000 years ago, the angle of inclination of Pluto's own rotation axis was 103 degrees, and the planetoid's climate was significantly different from the modern one, the climate was somewhat warmer. This means that the temperature of the surface of Pluto at that time could be higher, the pressure was higher, which ensured the existence of liquid nitrogen.

Over time, the inclination of the planetoid axis led to the movement of the tropics towards the poles of Pluto, while the Arctic regions shifted towards the equator. On Pluto it became much colder, and the nitrogen froze. In this case, there is still the possibility that liquid nitrogen is under the crust of nitrogen ice in the places where lakes used to be.

Plus, experts note the movement of glaciers on Pluto, so that the planetoid is not at all a "dead" object. Interestingly, in addition to nitrogen, there is also water ice . The NASA team received a better image of the distribution of ice on the surface of Pluto, combining two photographs with the New Horizons infrared instrument. Such an operation allowed to “strengthen” the signs of the presence of water ice, at the same time “drowning out” other “spectral signatures”. As a result, we can see how much water ice there is - the blue color shows the placement of frozen water on Pluto.



The interest of scientists is not only Pluto, but also its satellite Charon. According to some NASA scientists , Charon could have a subsurface ocean in the distant past. Over time, he gradually gave off heat, cooled, and eventually froze. Freezing, a huge mass of water expanded and destroyed the surface of Charon, which existed at the same volume of the ocean. As a result, today we can see huge cracks on the surface of a planetoid, the depth of which reaches 6.5 kilometers.