Aphrodite's girdle

Stephen Kane gets cited a few times around here, mostly for exoplanets. But he also sometimes ponders planets close to Earth. So here is something making waves in the Youtube sphere, alongside Sean N Raymond. It's about whether Venus had a moon.

I don't pretend competence in these fields. At any rate Kane's paper is talking about a hypothesis: if Venus had a moon early-enough in her history, then that moon would have been crushed and would have fallen by now.

I will, however, note that Venus is presently rather flat. We do except those volcanoes, mighty Maxwell Montes (the rare male exception to the naming rules there), and the Alpha/Beta Regiones. But widest of all, lies Aphrodite Terra. The "continent".

Aphrodite Terra tracks the Venereal equator. This always has stricken me as strange. Venus orbits extremely slowly, and that retrograde; such that the planet is more spherical than Earth's geode. Earth can run solar-synchronous satellites in orbit; for Venus, I guess they can stationkeep something with a sail at SVL1.

If a moon disintegrated in low Venus orbit more-or-less coplanar with Venus' ecliptic, that might account for colossal masses atop Venus' equator. Venus has resurfaced much of its plaons, yes. But maybe Aphrodite Terra was simply too massive for this effect to cover it all up. (Alternatively the moonfall happened recently.)

Nestorius and Cyril in context

As an occasional "Nestorian" blog, and certainly a pro-east-Syriac blog, I have some interest in that history. Matt Crawford traces the history to Nestorius' roots in Antioch. Good luck to Crawford; I hope he fares better than some others.

Cyril is meanwhile (somewhat) rehabilitated as not just making up theotokos (Latin, deipara) himself. Most people (like me, and Candida Moss) have seen Cyril as a base opportunist. We here have inherited Schwartz in 1928. Even if, of late, we have had to back off some of the Agora slanders against this Miaphysite saint.

Emperor Julian, born to Christian (Eunomian!) emperors, among his Christian foils had to address such as were saying theotokos or something like that. As a pagan, he recognised this term as pagan, like a mortal-ess birthing Heracles or Dionysus. The Eunomians weren't saying this; only a Miaphysite could say this. So Cyril was heir to a Miaphysite tradition. Gregory of Nazianzus knew this as of Apollinaris; later authors would see Eutychianism or "Julianism". Nevertheless Gregory (somehow) affirms theotokos.

Nestorius (and, I could add, John Chrysostom before him; and Diodore of Tarsus) grew up where Apollinarianism was staking its last redoubt. Theotokos could be tolerated anywhere else. Not in Antioch, says Crawford.

My reading of Crawford suggests he personally supports theotokos, or at least some form of Christian unity without taking that seriously. He wants to humanise Nestorius without accepting him. Maybe he can. I'll leave that aside for now.

The story may start with Paul of Samosata, all the way back in the middle 200s AD. He had posed, perhaps clumsily: for the Word is from above; Jesus Christ, a human being, is from here. The Council of Antioch shut him off AD 268. Eunomian subordinatism owes to this thought - if taking Paul's words literally. Athanasius devoted at least half his career against Eunomianism, maybe more than half. Nestorius' dyophysic might descend from Paul, also; but I think it turned out better, and I don't know how far Athanasius would have disliked Nestorius.

Gregory and (maybe) Athanasius could have threaded this needle. Real problems started emerging out West. Not the problems I'd expect.

One Leporius of Marseilles had propounded a notion of Christ as the merger of God and man. We don't really have the exact words he said, but the Masillians booted him out. Leporius then met Augustine in Africa and, basically, did the apology tour. The ensuing libellius survives through extensive quoting by John Cassian who brought it back to Gaul, with Augustine's personal imprimatur (if mostly an antiPelagian text, here). Cassian's aim was to rebut "Nestorians" who may well have preserved Leporius' earlier work.

Crawford carries over recent scholarship on Cyril's oeuvre, also: On the Incarnation of the Only-Begotten and that There is One Christ and Lord according to the Scriptures. This - for De Durand - preceded the whole feud with Nestorius. Nestorius' accession as the Patriarch of Constantinople, for Crawford, was unlucky for Nestorius, because Cyril was already an enemy of the dyophysitism who also shared his antiApollinarian credentials (or so he claimed).

I admit, I think Leporius got it right first-time. Augustine was always a momma's-boy who could easily have fallen in with the Ephesus councils, had he been born that late. I like to think - say - Jerome would have known better, hence why his work got translated to Syriac and passed East.

Some high-Isp experiments

ToughSF posted a few avenues of research, early last weekend. Both definitively drawing-board. I'd have said something but I couldn't click the link to one of the actual papers then, so - you get my take on them, today.

One is laser-hits on a liquid propellant. It splashes. As far as ToughSF knows, nobody's solved this one. Then he went on to note how lasers sploot droplets. Next!

The University of Surrey is asking about magnesium rockets. I'd heard of burning aluminium (as Surrey spell it) in oxygen, or maybe some even stronger oxidant like ozone. Burning metals isn't for Earth or LEO, but it intrigues me for low-grav takeoffs like our Moon - once bermed. Magnesium is just as common over there. But again, this looks rife with Unsolved Problems. The link will be here (pdf).

Absent a pdf, we do get an illustration. It looks like AI and makes little sense to my mortal eyesight. I just see magnesium is not planned for surface-to-orbit roggets the way some were talking aluminum. They want mass drivers, to take this fuel into orbit which rockets burn it up there. Into that topic, PlanetaryEngSys has butted: that mass drivers should start small, such that the capsule then fire the engines on that (parabolic) trajectory, to bring it to orbit. Seems more reasonable than Surrey's proposal frankly. ESA should pay that grant to them.

Quirinius

This blog has had some occasion to look into The Third Gospel's use of material and into its general tendency. Some of Luke's changes can be illustrated with textual-strain. Among the more-diverting results is Jesus' long gestation: he was conceived in Herod's reign (d. 4 BC) as in Matthew, but he came out among us during Quirinius' census (r. AD 6). Mary bore a burden quite unlike those of most women.

Miracles, or snark, aside: at least Joslin McDowell never entertained that notion, Protestant as he is (yeah, he's still alive). He prefers that Quirinius was there several years before. And maybe this Roman was; but he wasn't doing census in someone else's kingdom. Especially not Herod's.

Michael Kochenash explains Luke's plan. Luke knew of Roman-Jewish talk that the census was a flashpoint of rebellion, and this rebellion in particular. Kochenash goes further: he notes Josephus (a Galilean friend of Herod Agrippa II) in The Jewish War and Antiquities. The former, Josephus completed before the Campanian volcano buried Agrippa's sister; this eruption received note only in the latter.

TJW is well aware of Quirinius' census and of the revolts around it. But this book does not connect those events with the Revolt. The connexion becomes explicit only in JA. Kochenash does not see Josephus, here, arguing that point for or against other historians like Justus. It seems an idea that Josephus had just... come up with. A reasonable idea, to my mind anyway; but never mind that.

Kochenash does not think that Saint Luke had come up with that idea, either, by himself. Instead - Kochenash argues - Luke made of it a trope. Roma and Judaea came into serious Imperial contact through that census. Luke associates this contact with Jesus' infancy. What the Jews do to Jesus, is going to post a milestone to the Ninth Of Av; which the Jews perhaps could have averted, by embracing him as Christ.

Crossan would supplement, here, the Holy Spirit as Divine gloría. This has abandoned the Jews to settle upon the Apostles, and - finally - upon Peter and Paul who are headed westward.

Capstone of prophecy

Adrien de Jarmy seeks to make a wave in sira studies. Namely to separate "Constitution of the Madina" therefrom.

He points out that the Constitution hails Muhammad by titles taken from sura 7 and derived from sura 25. The document also delivers taṣliya, as the Dome of the Rock upon Muhammad - and upon [sura 3-4's] Jesus. One title, "sayyid of the mursalîn", is not on the Dome at all. That title, to boost the Arab Prophet over that other Semitic prophet, would be a development from 70s/690s Umayyad thought.

That tracks closer with the sura 33+48 complex, that Muhammad is the "seal". De Jarmy posits that it is overall 'Abbâsid. Huh.

According to Crone-Hinds' God's Caliph, the Umayyads were shifting to the ideology that the Caliphate was the postProphetic dispensation. For this, they could use sura 48. Just about any 'Abbâsite propagandum about how Muslims need to come together and avoid fitna can also be found in Umayyad sermons and poems; which Crone and Hinds did so find. The only real distinction is that 'Abbâsids (later!) came to interpret their caliphate as the stand-ins for the Prophet rather than, as earlier, shadows of God.

Overall I'd like to see comparisons of the Constitution with the treaty-literature. De Jarmy can make of that, his next project.

CI origins

B type Bennu, like Cb Ryugu, corresponds to CI meteors sent down here from Above - like local CM, CO and maybe CT.

Now Maria Schönbächler et al. have formally published this, as reported in Switzerland Wednesday.

When the CIs accreted, they accreted with water ice. That "when", for Ryugu and arguably for Bennu, could have been as early as 2My after CAI formation. They take those "calcium-aluminum-rich inclusion" chondrites to be the eldest of them all, I assume marking that 4.567Gy age we keep seeing. Our CI, and I assume CY also, would precede CM and CO (and CV). By this time, Jupiter had grown to 20 Earth masses.

The paper accepts that Bennu is rubble from a parent. But, without naming 142 Polana. Polana presently rolls around 2.4 AU. This is well within the 4-5 AU ice line today, and assuredly in CM times then, therefore has migrated. The paper's "figure 5" speaks of something called "ureilites" to be native down at ~2.5 AU, sooty achondrite rocks from some differentiated parent destroyed 5 My after CAI beyond Vesta.

Such chaos may account for why the authors seem cautious about assigning general CI/CY (for asteroids, B/Cb) distance from our (very) young sun at this time. And they don't speculate on the Grand Tack; this may be because they must admit hazy understanding of asteroids beyond Jupiter. CI was once mooted as far as 7 AU, assumed for instance here (slushball Ceres remains, I think, a migrate from up there). Other papers have put CO out 3.7 AU so, hey, why not for CI.

Redshifts

This blog has typically left the vagaries of the Big Bang and its cosmologic models to better bloggers. Lately we have a few hits on this topic, so I've decided to annotate them.

Key to deep cosmology is deep time. The universe expands, which by Doppler is colouring the further galaxies to the red. So the unit of time is like the unit of Marine Isotope Stages: the higher the number, here z_sys, the deeper. By the way using z means we can leave aside the vexatious Hubble Tension, as to compare stratum to stratum.

The Turtle is pointing to cosmic daybreak, a term connoting more abruptness than "dawn". At z≤15.1, we have stars and galaxies; hydrogen and helium stars, anyway. Never before/greater-than. Pace Zim.

Three galaxies, where we can better see them, are already forming "metals" at z=7.2883, 7.8 and even 9.31. There is a reïonism event between 8 and 7, ending 5.3, which, I take it, had been obscuring our sight of higher z's. (Damned if I'm going to use the -isation suffix like some Star Control 3 alien.)

At z=7.76, estimated 660My from the start, comes a Black Hole Sun. So that isn't at the cosmic daybreak, pace the title; it's older than the 7.29 galaxy but younger than the other two.

I think these ancient red dots could provide furnaces fit to meld all manner of heavier elements. They point to the creation of early black holes generally. Neutron stars, I'll grant, might take a mite longer to form.