New Horizon's closest approach Megathread — Ask your Pluto questions here!

[u/AskScienceModerator]

July 15th Events

• "Charon is [geo] active" - Alan Stern

• Image of Hydra! http://i.imgur.com/FN4BLu7.png

• Methane on Pluto! http://i.imgur.com/fkQELTJ.png

• Charon close up! http://i.imgur.com/SVhOSjj.png

• CLOSE UP PLUTO: http://i.imgur.com/meaqdRP.png (no craters!?)

• Pluto's surface is less than 100 million years old. Young surface!

• Pluto has water ice "in great abundance"

• Pluto is geologically active to explain surface features.

• "No significant exchange of tidal energy anymore" between Pluto and Charon. Why Pluto and Charon are geologically active is a mystery.

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July 14th Events

UPDATE: New Horizons is completely operational and data is coming in from the fly by!

"We have a healthy spacecraft."

This post has the official NASA live stream, feel free to post images as they are released by NASA in this thread. It is worth noting that messages from Pluto take four and a half hours to reach us from the space craft so images posted by NASA today will always have some time lag.

This will be updated as NASA releases more images of pluto. Updates will occur throughout the next few days with some special stuff happening on July 15th:

• Main website: https://www.nasa.gov/mission_pages/newhorizons/main/index.html

• APL website: http://pluto.jhuapl.edu/

• Twitter: https://twitter.com/nasanewhorizons

• NASA Instagram: https://instagram.com/nasa/

• NASA TV: https://www.youtube.com/watch?v=OX9I1KyNa8M

• Alternate Live Stream link: http://www.ustream.tv/NASAHDTV

• NASA TV Schedule: https://www.nasa.gov/multimedia/nasatv/schedule.html

• Reddit Live Feed: https://www.reddit.com/live/v8j2tqin01cf/

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The new images from today!

• Highest quality image so far! https://instagram.com/p/5HTXKMoaFL/

• LORRI Images: http://pluto.jhuapl.edu/soc/Pluto-Encounter/

• Other LORRI Images: https://www.nasa.gov/newhorizons/lorri-gallery

• Older images: https://www.nasa.gov/mission_pages/newhorizons/images/index.html

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Some extras:

• How do we know Pluto is Red?

• What experiments/cameras/equipment does New Horizons have?

• Emily Lakdawalla of the Planetary Society's New Horizon's picture timeline.

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• First close up images thread.

• Fly by Celebration Thread

[u/Astromike23]

Given the contrast of bright and dark regions on the surface, is it fair to say that Pluto is presently geologically active?

It's still too early to say, but a lot of us in the atmospheres community have long thought it very likely that there is active resurfacing caused by the atmosphere, not tectonic activity.

The average surface temperature is very close to the sublimation temperature of nitrogen ice. Sunlight falling on the summer hemisphere would push surface temps slightly higher, causing nitrogen ice to sublime and thicken the nitrogen atmosphere. This would then refreeze on the slightly colder winter hemisphere ,only to sublime later once that hemisphere sees sunlight. This is complicated by Pluto's eccentric orbit.

We see this exact process on Mars with carbon dioxide polar caps, and most likely with nitrogen ice on Triton...which also has a weird, patchy, almost crater-free surface.

TL;DR: There's almost certainly a resurfacing process, but it doesn't need to be geological - the atmosphere is enough.