Me too :-)

If the rotational axis is not pointing toward the observer, but rather somewhere in between of "toward observer" and "perpendicular to observer", then a binary might make sense also with respect to the non-detection of a lightcurve. In the animated-gif, "Ultima" passes in front of (or behind) "Thule", but the two components do not yet occult each other (at least not significantly). As long as the individual components are rather spherical, this would result in a rather shallow lightcurve because no "additional surface parts" would appear while the components move toward maximum elongation. Since no occultation took place, the characteristic dips of binary lightcurves are not there. Same for lightcurve features from potential eclipses since the sun is behind the observer.

Another 2 cents...

DSN Now is reporting start of the NYT 1 ("New York Times") data downlink. Signal strength is in the about -147.5 to -149 dBm range, as usual, and bit rate is shown as 841 bits/sec. The first post-flyby science data download has begun!

If you've witnessed a near-total-eclipse, you may well have spotted something 'odd' with the light and shadows. A slither of Sun casts much sharper shadows than the full half-degree disk. At Ultima Thule, whilst the daylight will be dimmer, by about 8 magnitudes, the shadows will be very much sharper.

Andy

That's not a useful analogy because it ranges from pitch black to daylight depending on season and latitude. It's more like a very dark rainy day.

Non lo sapevo. . incredible!

Looks like a raw peanut in shape. How long before we know if the peanut is in one piece or broken?

First I want to say congratulations to Alan and all the team for this flyby. Again in Spain has been a trending topic during the afternoon today.

I have made a quick and dirty way to look to all the images that are going to be downloaded from New Horizons that is useful if you want to sort by distance, date or exposure. The database will be uploaded as soon as there are new images avaiable: http://nahumchazarra.com/ultimalorri/viewer.php

Post-sunset brightness also depends upon transparency (humidity, dust). It's still useful, if not precise, for relating to all of us that it is certainly bright enough to see things.

Terrestrial sunlight is 400,000 times brighter than a full Moon, so the sunlight at Ultima Thule is about as bright as 210 full Moons. None of us, I think, have ever seen 210 full Moons at the same time, but as it's possible to read by the light of the full Moon, it certainly conveys that it's not such a dark place.

Put another way, it's about half as bright as sunlight at Neptune. If you've ever seen Neptune through a telescope, you can see that it's quite adequately lit for seeing shape and color.

Just about out of time for wild speculation, so Iʻll give it a last minute whirl....

Methinks that a close binary orbit would be short-lived (on the age-of-solar-system scale) because of small dissipative forces in the "neck" area. Debris could gather there and bounce around.

I am sure there would be cratering events in the history of MU69, but ice condensation/evaporation features cold also be present, plus solar wind and cosmic ray "processing". What the result of this looks like is truly anybodyʻs guess -- the best answer is "we donʻt know, but we will find out soon"....

I can be a bit more specific if it will help. If a spot on UT is normal to the sunlight, the illumination is about the same as a typical location on Earth in cloudless conditions with reasonably clean air having the sun about 1.5 degrees below the horizon. While it's true that aerosols and other factors change this I think the illumination normal to the ground will usually be within a factor of 2 of the nominal value. Perhaps I should try and check this with my sky simulation software and/or some pyranometer measurements.

It's kind of rare for a rainy day to be this dark (<0.1% of full zenithal sun) unless the sun is fairly close to the horizon. I'd place more typical values in cloudy/rainy conditions at 3-10% of the full sun case.

Disspiative forces even in case of a doubly-synchronous binary system with perfectly circular orbits?

A "wild speculation" for the moment:
Ultima Thule is a binary with two similarly-sized (but not equal-sized) components in a doubly synchronous rotation state with a period at the order of 16 hours and a pole-axis orientation that is approximately 45 to 60 degrees away from the observer (aka ~30° to ~45° tilted to the ecliptic plane). Diameter of larger component ~14 km, of smaller ~10 km; center range ~21 km, density ~0.8...0.9 g/cm3.

(Ok, this is really speculative...)

Hmm, we're expecting to see the oldest solid surface yet found in the solar system...
A cold classical Kuiper-belt binary, which has been in basically the same orbit for billions of years.
Hmm, this should be the first time we see what happens when sunlight and solar wind are the main weathering mechanism.

That should be a red-tholin-surface dominated by space weathering on the sunward side.
Might have some interesting long term torquing effects if material evaporates or sputters from the sunward side and collects on the dark side, might even have a "lake" of dust collecting in the neck between the main lobes.

The full moon produces about 0.1 lux illumination, so sunlight at Ultima Thule would be around 21 lux. This is between "twilight" (~10 lux) and "very dark overcast (~110 lux). Dimly lit publlc areas run between 20 to 50 lux, and home interiors are around 150 lux.

Im not very expert but unfortunately I think that two object very close aren't stable. I think necessary almost 30km space between two 10-15 km binary object for stability. But if they were two bodies so far away they were already resolved divided. This is why I believe that they will be two bodies in contact as a skittle or an hourglass.

I expect like-sand dune area like same little area over 67P comet

NYT 1 data download should be on the ground now.