Notes
Wednesday, 23 September 2026 · PlanetaryFormation.com
Liquid light core
InSight heard a liquid, lighter-than-expected core.
Mars
Mars has a liquid light core. A solid kernel is one reading.
InSight heard a liquid metal core. Reflections and waves that crossed the metal put the radius in two camps: a large low-density core near 1,830 kilometres, or a smaller denser core near 1,650 under a molten silicate layer. Either way the metal is light — something like 9 to 25 percent light elements, sulfur first. Mars has no global field now.
A 2025 reading of the same traces claims a solid kernel about 600 kilometres across, roughly one-fifth of Mars’s radius. That is not a settled inner Earth. How a solid kernel sits with a basal melt layer is still an open question.
This site reads Io through Mars as consecutive stages of one kind of planet, with living Earth as the present chapter. A liquid light core on Mars, and a possible late freeze on Earth near 565 million years, are two clocks. They do not measure 567 million years. The missions do not prove the handoff.
Figure 1. Two InSight radius camps and the claimed 2025 solid kernel. The liquid metal is the measurement. The kernel is one reading.
The ordinary view
A dynamo ran early on Mars and was off by the time the giant basins were emplaced, on the usual crater-count clock near 4.1 to 3.7 billion years. Southern highland crust is still magnetized. Hellas, Argyre, and Isidis are not. ALH 84001 still records a strong field near 3.9 billion years in the lab. Earth’s quiet interval at 565 million years, and the recovery that followed, is a different story on a different world.
Which clock is which
| What is claimed | What it is | What it is not |
|---|---|---|
| Liquid metal core | Measured by InSight: reflections and waves that crossed the metal | A finished Earth core |
| Radius camps ~1,830 or ~1,650 km | Large low-density core, or a smaller denser core under a molten silicate layer | A law that grows a planet |
| Light elements ~9–25 wt% | Sulfur first, then oxygen, carbon, hydrogen — a family of mixes | The name of the stage |
| Quiet basins, model age ~4.1–3.7 Ga | Magnetized highlands; Hellas, Argyre, Isidis quiet. Year is a crater isochron | Earth’s 565-million-year quiet interval |
| Claimed solid kernel ~600 km | One 2025 reading of the same InSight traces | A settled inner core, or the start of Earth-stage |
What would move a clock
| Row | What would move it | What would not |
|---|---|---|
| Liquid light core | A confirmed, dense, Earth-like inner core with a running dynamo | A new mix inside the same 9–25 wt% light-element band |
| Solid kernel ~600 km | The 2025 kernel shown to be an artifact | A few tens of kilometres of new radius |
| Quiet-basin clock | A lab age that puts a strong field on after the giant basins | A new crater-count model still near 4.1–3.7 Ga |
On this reading
This site reads Mars as the last window before living Earth. A liquid light core and no global field is what that window can look like. Earth’s possible late freeze sits at the open of the living chapter. Those are two clocks on consecutive stages. Crater-count years on the quiet basins are a model. They are not this site’s 567-million-year window.
What would weaken this
A confirmed, dense, Earth-like inner core with a running dynamo would take Mars out of the mostly-liquid, field-off box. A demonstration that the 2025 kernel is an artifact would put the solid center back off the table and leave the liquid light core as the fact. Neither result would prove a handoff.
What this page holds
Mars has a liquid light core. That is measured. A solid kernel about 600 kilometres across is one reading of the same traces, not a settled inner Earth. Mars has no global field now. Earth’s possible late freeze sits at the open of living Earth. This site reads those as two clocks on consecutive stages. The missions do not prove the handoff.
Sources
Stähler, Khan, Irving, Le Maistre and colleagues, 2021–2023. InSight liquid core; radius and density camps.
Khan et al., Nature 2023. Possible molten silicate layer above a smaller, denser metal core.
Sun, Huang and colleagues, Nature 2025. Claimed solid inner core ~613 km.
Lillis, Acuña, Connerney and basin studies. Magnetized highlands; quiet giant basins.