The Only Livable Planet

There is a new study soon to be published titled "Dynamical origin of Theia, the last giant impactor on Earth¹" which is available for a while on arXiv preprint server, and will appear (received 2 July, 2025) in a while in the journal Icarus which specializes in Solar System studies.

It is this last great impactor on this planet, along with significant other contributions from Solar System members, which makes Earth uniquely suitable for life. Subtract ANY of these influences and there would likely by no life on this planet.

In the early time of Solar System formation around 4.5 billion years ago, Earth received a large complement of carbonaceous chondrites (shorthand C Chondrites or CC) which are stony non-metallic meteorites not modified by heating. Five to ten percent of Earth’s mass came from this source. They contain up to 3% carbon as graphite, carbonates or organic compounds such as amino acids and can be up to 22% water. As well as C Chondrites that crashed into the planet, the last great impactor Theia provided another large supply of carbonaceous material. This impact also chipped off the Moon to orbit this planet which also provided an input for life via tidal action.

This present study looks at the sources of CC and NC (non-carbonaceous chondrites) as they were distributed in the Solar System and how they arrived on Earth, and how Earth ended up with more CCs than the other rocky (inner) planets.

Jupiter played a major role in shepherding material around in the Solar System, truncating the asteroid belt and scattering material from the outer Solar System into the path of the rocky planets, especially Earth. The CCs were only sourced from the cooler, outer reaches of the Solar System. Part of Jupiter’s effect was caused by a shift in its orbit. There also were contributions enabled by the outer ice giant planets.

As quoted in a review article in phys.org, written by Evan Gough, of Universe Today:

“A million things had to be just right for Earth to become the life-sustaining world it is today. How likely it is that there are other worlds out there like it is unknown. It may take more than being in a habitable zone for an exoplanet to support life. There may be a bewildering number of variables that have to go right, including outer giant planets that migrate and deliver carbon to rocky worlds in habitable zones.”

Earthrise, Apollo 8, NASA

So it appears that all this hopium in finding another planet with life on it is just wishful thinking, apparently their hope is that a planet like Earth might exist in many places, making it less important not to ruin this one, or tear it apart like a resource-planet. Well, smarten up, people, THIS IS IT - this is most likely ALL THERE IS, and stupid humans are ruining it, our only home. Can you imagine a species so stupid as to have WARS on the only livable planet? Or genocides? Or spinning off social capital into layers of worthless derivatives ensuring poverty? And an Empire conjuring up a “next threat” on a pathway to nuclear annihilation? The amount of shame from all this should be enough to get humans to SHUT UP for eternity. Any time you feel hubris or nationalism building up, remember this undying shame - it is on you.

Note that Substack counts this as “read” only if you click on the title and view in your browser. If you don’t dislike this post, click on “Like,” this gives a higher-ranking in substack search. All these posts are mirrored on my web site at https://www.mccroskey.ca/limitstoprogress.htm

1) - branco2025dynamicalorigintheiagiant,
      title={Dynamical origin of Theia, the last giant impactor on Earth}, 
      author={Duarte Branco and Sean N. Raymond and Pedro Machado},
      year={2025},
      eprint={2507.01826},
      archivePrefix={arXiv},
      primaryClass={astro-ph.EP},
      url={https://arxiv.org/abs/2507.01826}