This page lists every source the article rests on, says what it actually measured, and states which side of the question it helps. Unlike the star formation companion, a substantial fraction of these sources support the creationist objection rather than refuting it.
Verification rule used throughout. No quotation was taken from a summarising tool. Every arXiv and journal source was downloaded as a PDF and searched in extracted text. The Weidenschilling paper is a 1977 scan and was read through OCR; the two quoted sentences were checked against the surrounding page. Web articles were downloaded and stripped locally.
The creationist source
| Source | What it argues | Notes |
|---|---|---|
| Hartnett, Planetary system formation: exposing naturalistic storytelling, creation.com, 17 Feb 2016 | Dust cannot grow past the bouncing/fragmentation limit; metre bodies fall into the star in 100 years; the angular momentum split is unexplained; no planetary system has been seen forming | The most detailed young-earth treatment located. His sources are quoted accurately and his mechanical objections are substantially correct. Three of his claims have been overtaken by observations published after 2016. |
Hartnett's technical sources are a Swinburne University course module (HET620-M09A01) and Carroll & Ostlie's An Introduction to Modern Astrophysics, 2nd ed., pp. 862–863. Neither was obtained directly; both are quoted only as he quotes them.
The barriers — sources that support the objection
| Source | Measurement or result | Which way it cuts |
|---|---|---|
| Weidenschilling, MNRAS 180:57, 1977 | Radial drift velocities "of the order of 104 cm/s for metre-sized objects"; "For s ∼ 100 cm, τc < 100 yr at r = 1 AU" | For the objection. The primary source for the metre-size barrier, and Hartnett's figure is exactly right. |
| Zsom et al., A&A 513:A57, 2010 | Laboratory-calibrated collision model at 1 au: growth stops by bouncing, maximum particle mass ≈ 1 g, insensitive to gas density and turbulence | For the objection. The barrier is worse than the fragmentation picture it replaced, because bouncing produces no fragments. |
| Blum & Wurm, ARA&A 46:21, 2008 | Laboratory review: sticking fails above ~1 m/s; "the direct formation of kilometer-sized planetesimals cannot (yet?) be understood via sticking collisions" | For the objection. Widely quoted by creationists, accurately. |
| Gundlach & Blum, ApJ 798:34, 2015 | µm water-ice particles stick below 9.6 m/s, ~10× the silicate threshold; erosion above 15.3 m/s | Against the objection, as of 2015. |
| Musiolik & Wurm, ApJ 873:58, 2019 | Ice surface energy falls by almost two orders of magnitude from 273 K to 180 K; at disk temperatures ice is not stickier than silicate | For the objection, and it reopens the standard escape route. Contested. |
| Birnstiel, review, arXiv:2312.13287, 2024 | Summarises the unsettled state of the fragmentation-velocity question | Neutral; establishes that the dispute is live. |
| Manara, Morbidelli & Guillot, A&A 618:L3, 2018 | Class II disk dust masses, Gaia-corrected, are comparable to or lower than the heavy-element content of known exoplanet systems | For the objection. A real, unresolved budget problem, and one creationists have not used. |
| Helled & Bodenheimer, ApJ 789:69, 2014 | Uranus and Neptune require "very specific conditions"; with higher accretion rates the problem becomes that they should have become gas giants | Partly for the objection. The problem changed shape rather than disappearing. |
The proposed crossing — and its tests
| Source | Result | Which way it cuts |
|---|---|---|
| Youdin & Goodman, ApJ 620:459, 2005 | Solid-gas drag is linearly unstable; pebble clumps concentrate | Against the objection. Theory. |
| Johansen et al., Nature 448:1022, 2007 | Boulders "undergo efficient gravitational collapse in locally overdense regions in the midplane"; collapse is much faster than radial drift | Against the objection. Simulation. |
| Simon et al., ApJ 822:55, 2016 | Streaming instability with self-gravity gives the planetesimal mass and size distribution | Against the objection. Simulation. |
| Morbidelli et al., Icarus 204:558, 2009 | Reproducing the 100 km bump in the asteroid size distribution requires initial planetesimals of ~100 km — solids "jumped … without passing through intermediate values" | Against the objection, and independent. Derived from asteroid data, not written to defend the instability. |
| Nesvorný et al., Nat. Astron. 3:808, 2019 | Kuiper belt binaries are prograde and equal-sized as gravitational collapse predicts; capture models implying retrograde orbits "can be ruled out" | Against the objection. A prediction that could have failed. |
| McKinnon et al., Science 367:eaay6620, 2020 | Arrokoth is "the product of a gentle, low-speed merger"; 10 m/s impacts shear rather than merge; even 5 m/s distorts | Against the objection. A photograph of what the mechanism predicts. |
| Lambrechts & Johansen, A&A 544:A32, 2012 | Pebble accretion shortens core growth by 30–1,000× at 5 au and 100–10,000× at 50 au | Against the objection, with stated preconditions. |
| Drążkowska et al., Protostars and Planets VII, 2023 | Review of the whole chain from pebbles to exoplanets | Background. |
| Johansen et al., Protostars and Planets VI, 2014 | Review of planetesimal formation | Background. |
Observations of planet formation in progress
| Source | Measurement | Which way it cuts |
|---|---|---|
| ALMA Partnership, ApJL 808:L3, 2015 | HL Tau: ringed disk around a ≤1–2 Myr source | Against the objection. |
| Andrews et al., ApJL 869:L41, 2018 (DSHARP) | Rings and gaps are common in disks at high resolution | Against the objection. |
| Keppler et al., A&A 617:A44, 2018 | PDS 70 b: point source at 195 mas (~22 au) inside a 54 au gap, five epochs, three bands, three instruments, bound, planetary mass | Against the objection, decisively. |
| Haffert et al., Nat. Astron. 3:749, 2019 | Two Hα sources in the gap — PDS 70 b and c — both accreting | Against the objection. |
| Benisty et al., ApJL 916:L2, 2021 | ALMA at 2.3 au resolution: a circumplanetary disk around PDS 70 c | Against the objection. A disk around a planet inside a gap inside a disk. |
| Segura-Cox et al., Nature 586:228, 2020 | IRS 63: four rings around a protostar under 500,000 years old | Against the objection; also pushes planet formation earlier. |
| Tychoniec et al., A&A 640:A19, 2020 | Class 0 disks hold a median 158 M⊕ of dust, Class I 52 M⊕ — 10× and 3× the Class II values. The budget closes only if planet formation starts in Class 0 | Partly answers the Manara problem, at the cost of moving the whole timeline earlier. |
| Mills et al., Nature 533:509, 2016 | Kepler-223: four planets in a librating 4:3, 3:2, 4:3 resonant chain | Against the objection. Migration test. |
| Luger et al., Nat. Astron. 1:0129, 2017 | TRAPPIST-1: seven planets in a full resonant chain | Against the objection. Migration test. |
NASA Exoplanet Archive, pscomppars, 9 Aug 2026 |
6,336 confirmed planets, 4,749 host stars, 567 planets in ≥4-planet systems | Context. |
Angular momentum
| Source | Measurement | Which way it cuts |
|---|---|---|
| Belloche, EAS Publ. Ser. 62:25, 2013 | Specific angular momentum by stage. Dense cores 1021–22 cm² s−1; Sun 1015; solar system 1017; exoplanet systems 1016–18 | Both. States the real 6–7 order-of-magnitude problem, and shows the solar system is typical of exoplanet systems. |
| Lee, arXiv:2607.28056, 30 Jul 2026 | Core-to-disk angular momentum profiles in HH 212, HH 211 and B335 match inside-out collapse with ejection by jets and winds | Against the objection. The removal is measured. |
| Bailey, Batygin & Brown, AJ 152:126, 2016 | The Sun's obliquity "remains an open question"; their own answer requires Planet Nine | Partly for the objection. A genuine unexplained feature of our system. |
| Bouvier et al., Protostars and Planets VI, 2014 | Angular momentum evolution of young stars; disk-locking and magnetised winds | Background. |
| Computed here | Sun holds 99.866 % of the mass, ~0.6 % of the angular momentum; Jupiter 61.5 % of the planetary total | Corrects Hartnett's "1 %" in his favour, then shows why the split is largely geometric. |
Arithmetic computed here, not quoted
- Angular momentum budget. Planetary orbital angular momentum
L = M√(GM☉ a(1−e²))summed over the eight planets gives 3.13 × 1043 kg m² s−1, of which Jupiter is 1.93 × 1043 (61.5 %). The Sun's spinL = kM R²ωwith the helioseismic moment-of-inertia factor k = 0.070 and a 25.38-day sidereal period gives 1.93 × 1041 — 0.61 % of the total. Using k = 0.059 instead gives 0.52 %. Sun's share of the mass: 99.866 %. - Why the split is geometric. Orbital angular momentum scales as √a. Jupiter's orbital radius is about 1,100 solar radii, so moving Jupiter's mass to the Sun's surface would divide its angular momentum by about 33.
- Specific angular momentum of the whole solar system: (3.13 × 1043 + 1.93 × 1041) ÷ 1.99 × 1030 = 1.6 × 1013 m² s−1 = 1.6 × 1017 cm² s−1, matching Belloche's tabulated 1017.
Not obtained
- Blum & Wurm 2008 was read through the extensive verbatim excerpts in this site's research notes plus the openly posted Berkeley copy; the Annual Reviews version of record was not purchased.
- Carroll & Ostlie, 2nd ed., pp. 862–863 and the Swinburne module HET620-M09A01 — Hartnett's sources, quoted only as he quotes them.
- Youdin & Goodman 2005 and Johansen et al. 2007 were downloaded but are cited for their headline results only; no quotation is taken from either.
- Spike Psarris, What You Aren't Being Told About Astronomy — the origin of several circulating solar-system claims. Not obtained, as noted also in the solar system age article.
What would change the verdict
- Against the standard account: if the streaming instability's required solid enhancement turns out not to arise in real disks; if the disk-mass problem does not close even with Class 0 formation; if the ice fragmentation velocity settles near 1 m/s and no other route past the barrier survives.
- For it: a direct detection of streaming-instability filaments in a disk; a measured planetesimal size distribution in a young disk; resolution of the disk-mass budget.
Next updates
- Track the ice fragmentation-velocity dispute. It is the single most movable number in this article.
- Watch for further ALMA and JWST work on PDS 70 and on the growing list of gap-hosting disks.
- Revisit the Uranus/Neptune problem after the next generation of pebble-accretion population syntheses.