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Ask why. Follow the evidence.

Sources

The papers behind the science, with recent and contested findings marked.

08

Sources

What each stage rests on. Status is marked: solid is textbook or multiply confirmed, recent is 2022–2026 and not yet consensus, contested is a live dispute or a withdrawn claim.

  1. Late accretion offers a pathway to a misaligned disk (IRAS 04125+2902, 2025); infall-driven disk misalignments (2026). recent
    arxiv.org/html/2509.06564 · used in The stages: Protostar
  2. Lark et al. 2024, Nature Communications: a diamond-bearing core–mantle boundary on Mercury. (55 Cancri e, the “diamond planet”, is no longer thought carbon-rich: Hu et al. 2024, Nature.) recent
    www.nature.com/articles/s41467-024-49305-x · used in The stages: Protostar
  3. The disk and dust models: Lynden-Bell & Pringle 1974; Birnstiel, Klahr & Ercolano 2012; Ormel & Liu 2018; Bitsch et al. 2018; the DSHARP survey (Andrews et al. 2018) for the rings. solid
    iopscience.iop.org/article/10.3847/2041-8213/aaf741 · used in The stages: Protoplanetary Disk and Giant Impacts
  4. Kruijer, Kleine & Borg 2020: the great isotopic dichotomy of the early Solar System; the Jupiter barrier. solid
    web.gps.caltech.edu/classes/ge103/Readings/Week2-3_OriginsQu… · used in The stages: Protoplanetary Disk and Giant Impacts
  5. Avdellidou et al. 2024, Science: the giant-planet instability dated to 60–100 million years after formation. recent
    www.science.org/doi/10.1126/science.adg8092 · used in The stages: Protoplanetary Disk and Giant Impacts
  6. De et al. 2023, Nature: an infrared transient from a star engulfing a planet; Lau et al. 2025: JWST shows the planet spiralled in. recent
    www.nature.com/articles/s41586-023-05842-x · used in The stages: Protoplanetary Disk and Giant Impacts
  7. Foley & Smye 2018: carbon cycling and habitability of Earth-sized stagnant-lid planets; Walker, Hays & Kasting 1981 for the thermostat. solid
    www.liebertpub.com/doi/10.1089/ast.2017.1695 · used in The stages: Hadean
  8. Kite & Ford 2018, ApJ: habitability of exoplanet waterworlds. solid
    sseh.uchicago.edu/doc/Kite_and_Ford_ApJ_2018.pdf · used in The stages: Hadean
  9. Tomkins et al. 2024, EPSL: evidence suggesting that Earth had a ring in the Ordovician. contested
    www.researchgate.net/publication/385458199_Evidence_suggesti… · used in The stages: Hadean
  10. Wu et al. 2021, Nature Communications: a six-fold increase of pCO₂ during the Permian–Triassic extinction; Cox et al. 2016 for flood-basalt weathering as a Snowball trigger. solid
    www.nature.com/articles/s41467-021-22298-7 · used in The stages: Hadean
  11. Mills et al. 2025, Science Advances: a reassessment of the “hard-steps” model for the evolution of intelligent life. recent
    www.science.org/doi/abs/10.1126/sciadv.ads5698 · used in The stages: Archean
  12. Moody et al. 2024, Nature Ecology & Evolution: the nature of the last universal common ancestor and its impact on the early Earth system. recent
    www.nature.com/articles/s41559-024-02461-1 · used in The stages: Archean
  13. Dated gene duplications elucidate the evolutionary assembly of eukaryotes (Nature 2025); a small oxygen rise and the Cambrian explosion (Southampton, 2024). recent
    www.nature.com/articles/s41586-025-09808-z · used in The stages: Archean
  14. Belcher & McElwain 2008 and Scott & Glasspool 2006, PNAS: the oxygen limits of fire over the Phanerozoic. solid
    www.pnas.org/doi/10.1073/pnas.1011974107 · used in The stages: Archean
  15. Roth 2015, Phil. Trans. B: convergent evolution of complex brains and high intelligence; Ogura et al. 2004 on the octopus and human camera eye. solid
    royalsocietypublishing.org/rstb/article/370/1684/20150049/22… · used in The stages: Phanerozoic
  16. Lingam & Loeb 2023, ApJ: a Bayesian analysis of technological intelligence in land and oceans. recent
    iopscience.iop.org/article/10.3847/1538-4357/acb6fa · used in The stages: Phanerozoic
  17. Kiang et al. 2007 (NASA): the colour of plants on other worlds; red-shifted oxygenic photosynthesis under M-dwarf starlight (2026). solid
    www.nasa.gov/vision/universe/watchtheskies/spectrum_plants.h… · used in The stages: Phanerozoic
  18. Vick, Su & Lai 2023: high-eccentricity migration with disk-induced misalignment favours perpendicular hot Jupiters. recent
    iopscience.iop.org/article/10.3847/2041-8213/acaea6 · used in The stages: Protoplanetary Disk and Giant Impacts
  19. Wisdom et al. 2022, Science: loss of a satellite could explain Saturn’s obliquity and young rings. contested
    www.science.org/doi/10.1126/science.abn1234 · used in The stages: Protoplanetary Disk and Giant Impacts