Now you see it, now you don't

        Well, actually, now you don't see it, now you still don't. I'm referring to Nibiru, or Tyche, Planet X or Planet Nine. A trans-Neptunian object in a 15,000-year orbit, much loved by pseudo-astronomers including Messrs. Hoagland & Bara. These two half-educated speculators wrote about it in their 2007 book Dark Mission (NOT a NYT best-seller despite its authors' frequent claims). The speculation was, actually, either one massive planet in a posigrade orbit, or two smaller ones going retrograde (p.115, 2nd edn.). It was based on a diagram plotting specific luminosity (W/kg) vs. specific angular momentum (sq cm/sec) that hoagland took from a book called The New Solar System then slapped his own copyright on it. The figures the diagram uses include, in each case, the named body plus anything in orbit around it.

        According to him, the solar system as a whole has less angular momentum than it should, and Planet X (or Planets -y and -z) would bring it into line. I don't think either Hoagland or Bara understand what specific angular momentum means (it means angular momentum per unit mass, so to arrive at the true angular momentum of the solar system, you'd need to multiply that number for 'Sun' in the diagram—4 x 10²⁰ approx—by the mass of the whole kit and caboodle).

        When, in January 2016, Batygin & Brown of CalTech lent their support to Planet X on the basis of the orbital anomalies of six Kuiper Belt objects, Mike Bara did the Toldya dance on his blog. But he got totally confused between Planet X and Nemesis, a hypothetical brown dwarf companion of the Sun that has nothing to do with the Kuiper Belt. Stuart "astroguy" Robbins expressed more than a modicum of skepticism about the announcement from CalTech.

An icy disc
        This week Sefilian and Touma of Cambridge University and the American University of Beirut have come up with a model that explains the orbital anomalies without requiring a massive trans-Neptunian object (TNO).^{note 1}

 "We wanted to see whether there could be another, less dramatic and perhaps more natural, cause for the unusual orbits we see in some TNOs. We thought, rather than allowing for a ninth planet, and then worry about its formation and unusual orbit, why not simply account for the gravity of small objects constituting a disc beyond the orbit of Neptune and see what it does for us?
"If you remove planet nine from the model and instead allow for lots of small objects scattered across a wide area, collective attractions between those objects could just as easily account for the eccentric orbits we see in some TNOs." --Antranik Sefilian

        The hypothesised icy disc probably has a mass equivalent to ten Earths—not very much^{note 2}, but Sefilian and Touma say it's enough. They aren't claiming to have actually observed such a disc, just to have worked out the physical implications assuming it exists. It's important to understand that nobody claims to have actually observed Planet X, or Nibiru, either. Now you don't see it, now you still don't.

=========================/ \========================
[1] Antranik A. Sefilian, Jihad R. Touma. Shepherding in a Self-Gravitating Disk of Trans-Neptunian Objects. Astronomical Journal, 2019

[2] Neptune is 17 Earths, Jupiter 318

Bara banned!

I wonder if that's the real reason....

Update:

Mike Bara, unorthoDOX

     Mike Bara really does love the word imbecile. In the world of twitter, anyone who disses his fave sports teams gets that epithet, and also anyone who thinks it's tacky to turn an image of a landslide on the Moon upside down and label it as a "crystal city". Actually, for the latter, he sometimes favors  "lick my balls, asshole". He does have a way with words, although it's not a way I favor personally.

        Of course he didn't really hold up that sign during his recent Tell The Truth Wednesday vlog—that's just an internet fake, I can't think where it came from. What he did hold up was an envelope containing two free tix to Alien Snowfest, a prize he was offering to one of his fans. The interesting part is that the lucky prizewinner got to see her name and full street address plastered across YouTube thanks to Bara. The address was entirely readable.

Congratulations to the China National Space Agency

        Chang'e 4 touched down on the floor of Von Kármán crater at 02:26 GMT today. This is the first image from the lander:

photo: CNSA

        There is no direct communication between Earth and Chang'e 4. Data is relayed via a satellite called Queqiao (trans: Magpie bridge) at the L2 libration point, 64,000 km beyond the Moon. Queqiao was pre-positioned in May last year. I don't know whether the relay has spare channels that might be available to other nations' far side landers, if and when they arrive.

        Von Kármán is an enormous crater, whose Eastern edge is right on the 180° longitude. The cross marks the exact landing point, 45.471° S 177.606° E.

        Here's where it is in relation to the whole far side. The very large dark area at 26.5° N, 148° E is the Mare Moscoviense, one of the very few maria on this side of the Moon. Tsiolkovsky, the crater that Ken Johnston says contains an alien base, is also notably dark, at 20.4° S, 129.1° E (almost due NW from Von Kármán). The so-called "crashed spaceship" visited by the non-existent Apollo 20 mission is at 18.66° S, 117.68° E; NW again from Tsiolkovsky and well over toward the near side.

ref: Space.com

Trivia: The crater is named for Theodore Von Kármán (born Kármán Tódor in Budapest), a mathematician and aeronautical engineer who was one of the founders of JPL. The public auditorium at JPL is also named for him.

Update 4 January:

photo: CNSA

        This is how far the Yutu rover has progressed. It will now go into sleep mode for six days to assure survival during the hottest part of the lunar day.

Update 11 January:

The real-time descent and landing video is now available.

Solution to the year-end acrostic

"Following the political tumult and excitement of the first successful lunar landings, the White House and NASA dramatically changed the direction of the entire space program under the excuse of a lack of public interest and insufficient funding."
--Richard Hoagland, Dark Mission

A. Ruffians
B. Ice-T
C. Cupped
D. Hellhole
E. Acceded
F. Ratline
G. Duffle
H. Hexadecimal
I. Oberg
J. Accutron
K. George Noory
L. Lustful
M. Aching
N. Nuffield
O. Diffidence
P. Dwelt
Q. Atticum
R. Rosh Hashannah
S. Kitten paws
T. Morningstar
U. Institute
V. Space station
W. Staunch
X. Illuminati
Y. Often
Z.  Netsex

For reference, the acrostic is here:
https://www.dropbox.com/s/9znevp8qmax7kqh/blogacrostic.pdf?dl=0