New Horizons

[Green Baron]

Nope, the spherical shape is not through their own gravity. They are much too small.

[lajoswinkler]

11 minutes ago, kerbiloid said:

I mean not the collision, but their self-gravity pressure.
It was enough to make both of them almost spherical. So, it probably should spherize them again.
Just married?

Ever seen graupel?

 

They are spherical because of gases depositing into soild from all sides. It's very similar with Ultima Thule and other such bodies. Later, two of them got slowly attracted and now are sitting together.

[KG3]

Are we likely to find that objects that formed in this part of the solar system are more likely to be spherical regardless of size unlike objects that formed closer to the sun like Bennu?  

1 minute ago, lajoswinkler said:

Ever seen graupel?

 

Graupel, are those the same a hail stones?

[lajoswinkler]

@LaydeeDem I used Charon's north pole's color from the natural color image (blurred it massively and picked the color) to colorize Ultima Thule, and then brought the contrasts and lightness down to appear similar to those few Juno's Ceres photos that are not overexposed. Granted, Ceres has lower albedo but it's closer to the Sun so yeah, take this with a grain of salt. I think it matches my idea of chernozem pretty good. Consider this could be something like seeing it with naked eye in a spacecraft, in those light conditions. For best effect, open in something without white background to blind you.

20 minutes ago, KG3 said:

Are we likely to find that objects that formed in this part of the solar system are more likely to be spherical regardless of size unlike objects that formed closer to the sun like Bennu?  

Graupel, are those the same a hail stones?

No, graupel is fluffy, porous. Like styrofoam balls, almost.

Edited January 3, 2019 by lajoswinkler

[tater]

Generally for icy planets the lower limit for hydrostatic equilibrium is on the order of 200km diameter as I recall. The bulk modulus of the material they are composed of still matters, but things a few km across simply aren't massive enough for gravity to achieve sphericity from itself alone. Planetesimals and cometesimal formation is obviously not super well understood, particularly at small sizes. We're basically now seeing the first such objects in situ. UT, plus Pluto's moons;  Styx, Kerberos, Nix, and Hydra. Of the later, 2-3 of them might well be 2 merged bodies, so maybe such low-speed collisions and merging are relatively common.

[tater]

 

 

[cubinator]

Called it! I knew they'd have a 3D picture.  

[lajoswinkler]

It's a pretty bad anaglyph because we're having mainly rotation. These things require translation parallax, and both images need to be aligned horizontally. But it's the best we can have right now. It's going to get better when we get images while the probe was going sideways to the body.

[KG3]

12 hours ago, lajoswinkler said:

 

No, graupel is fluffy, porous. Like styrofoam balls, almost.

 

Oh, that's graupel.  I have seen it before but never knew there was a word for it.  I don't recall ever seeing it as large as shown in your first picture of it!

[StrandedonEarth]

9 minutes ago, KG3 said:

Oh, that's graupel.  I have seen it before but never knew there was a word for it.  I don't recall ever seeing it as large as shown in your first picture of it!

Yeah, I've only ever described it as "snow pellets", which is what UT is probably made of

[LaydeeDem]

11 hours ago, lajoswinkler said:

@LaydeeDem I used Charon's north pole's color from the natural color image (blurred it massively and picked the color) to colorize Ultima Thule, and then brought the contrasts and lightness down to appear similar to those few Juno's Ceres photos that are not overexposed. Granted, Ceres has lower albedo but it's closer to the Sun so yeah, take this with a grain of salt. I think it matches my idea of chernozem pretty good. Consider this could be something like seeing it with naked eye in a spacecraft, in those light conditions. For best effect, open in something without white background to blind you.

This is excellent! For an object that's darker than asphalt in some places, I think you've done a good job representing what MU69 might look like to human eyes. Color looks very close to the dark patches on both Pluto and Charon. It'll be exciting to see if this expectation holds true as new data is down-linked and released to the public.

 

13 hours ago, tater said:

Generally for icy planets the lower limit for hydrostatic equilibrium is on the order of 200km diameter as I recall. The bulk modulus of the material they are composed of still matters, but things a few km across simply aren't massive enough for gravity to achieve sphericity from itself alone. Planetesimals and cometesimal formation is obviously not super well understood, particularly at small sizes. We're basically now seeing the first such objects in situ. UT, plus Pluto's moons;  Styx, Kerberos, Nix, and Hydra. Of the later, 2-3 of them might well be 2 merged bodies, so maybe such low-speed collisions and merging are relatively common.

Bi-lobed bodies appear to be very common in the solar system. Not just MU69 and Pluto's moons, but also several comets: 67P/C-G, 1P/Halley, 19P/Borelly, 103P/Hartley... etc.

This paper suggests that these kinds of bodies actually form this way, precipitating as a binary pair and then eventually collapsing due to orbital decay to form the bi-lobed shape we see today. Such collisions would have happened at incredibly low velocities. On the order of 70-90 cm/s, a little over half the average human walking speed. (Drawing by James Tuttle Keane)

 

As mentioned by @lajoswinkler these bodies have the consistency of graupel. They're like the outer solar system's version of "rubble piles" a la Ryugu or Bennu. These pairs likely would accrete into a single mass if their interiors hadn't undergone sufficient cohesion yet. For bi-lobes like MU69 or 67P, this suggest there was quite some time between the formation and the collapse of the binary pair. Long enough for radioactive heating to reinforce the interiors of the two lobes, at least.

[YNM]

I think the reason these bodies are rounded is because they're just a fluff of material. It's even less compacted than silt and loam.

 

I wonder however, could they hold electrostatic charges ?

[Mad Rocket Scientist]

1 hour ago, LaydeeDem said:

This is excellent! For an object that's darker than asphalt in some places, I think you've done a good job representing what MU69 might look like to human eyes. Color looks very close to the dark patches on both Pluto and Charon. It'll be exciting to see if this expectation holds true as new data is down-linked and released to the public.

I wonder if it would look somewhat brighter than this, since while the moon is darker than asphalt, our eyes adjust enough that it looks much brighter:

With so little else out there to compare too, we might perceive it as much brighter than it is, even with so little light out there.

[kerbiloid]

Spoiler

Either it's , or it's .

But anyway they have found an asteroid spawner.

 

[KerikBalm]

1 hour ago, Mad Rocket Scientist said:

I wonder if it would look somewhat brighter than this, since while the moon is darker than asphalt, ....

To be fair, that comparison should be done with a full moon, or looking at the asphalt at an appropriate angle, because the brightness changes due to the opposition effect.

https://en.wikipedia.org/wiki/Opposition_surge

Edited January 4, 2019 by KerikBalm

[YNM]

On 1/4/2019 at 1:28 PM, Mad Rocket Scientist said:

moon is darker than asphalt

I think this goes more to their fine dust granules rather than actual color, almost kind of like a wet cloth is in general darker than a dry one. Deposited volcanic ash is also 'darker' than asphalt as it's roughly the same stuff.

I suppose it's more telling about how our brain doesn't result us the truth - it results in an "optimized" version of the image, for us to see.

[tater]

We have large fields of basalt around here. Up close it's pretty black, but still not dark in sunlight:

This goes on for many km, BTW. And just to the right in this picture (maybe 80km, but this malpais formation is about 70km long) is White Sands.

Spoiler

 

[Green Baron]

I like open landscapes.

New Horizons is in conjunction with the sun, until ~11th. No comms until it peeps around the sun's edge again.

On second thought, the encounter happened quite close to this ... phew.

Edited January 5, 2019 by Green Baron

[YNM]

On 1/6/2019 at 12:52 AM, tater said:

Up close it's pretty black, but still not dark in sunlight

Yeah, they're fairly shiny (reflective). Which is why I think it only looks dark not because the thing is actually black, but because it scatters light very well due to it being a loose dust. Kind of like graphite slate vs. graphite powder.

Edited January 7, 2019 by YNM

[EchoLima]

Anyone know when we'll next see data?

[ThatGuyWithALongUsername]

2 minutes ago, EchoLima said:

Anyone know when we'll next see data?

I wish- hard to go into reasons why without invoking politics, but, long story short, the US government is currently shut down. This means that most government staff are not on duty and are not getting paid unless it is "essential," which evidently does not cover NASA's PR team.

Edited January 14, 2019 by ThatGuyWithALongUsername

[IncongruousGoat]

10 minutes ago, ThatGuyWithALongUsername said:

I wish- hard to go into reasons why without invoking politics, but, long story short, the US government is currently shut down. This means that most government staff are not on duty and are not getting paid unless it is "essential," which evidently does not cover NASA's PR team.

Slight correction: The U.S. government is partially shut down. Defense, Labor, Education, Energy, Veteran's Affairs, the District of Columbia, and bits of other agencies are currently funded, with the rest being shut down. It would be really bad for the Army to be without funding. But, yes, NASA is shut down because of politics.

[KG3]

12 hours ago, IncongruousGoat said:

. But, yes, NASA is shut down because of politics.

How does that effect missions?  Or does it mostly just effect things like press releases?  

[YNM]

14 hours ago, EchoLima said:

Anyone know when we'll next see data?

Probably when they have money to show us stuff again.

Meanwhile the main downlink is still ongoing I think.

1 hour ago, KG3 said:

How does that effect missions?  Or does it mostly just effect things like press releases?  

I think only the publicly visible part is affected. The science stuff isn't, thanks to valiant effort from the teams I suppose !

[tater]