Planetary scientists long debated whether material from beyond Jupiter contributed substantially to Earth’s mass; earlier studies suggested anywhere from a modest to a large fraction might come from the outer solar system. To address this, Paolo Sossi and Dan Bower at ETH Zurich re‑examined published isotopic ratios across a wide range of meteorites, including samples linked to Mars and the asteroid Vesta. The article appears in Nature Astronomy.
Isotopes are atoms of the same element that differ in mass. The team combined data from ten different isotopic systems and applied a specialised statistical approach, whereas much previous work relied mainly on two isotopic systems. Using this broader data set, the researchers conclude that Earth’s building material originates from a single inner‑solar‑system reservoir.
The analysis finds Earth is composed of non‑carbonaceous (inner) material and that contributions from the outer solar system are likely under a very small fraction or possibly zero. The authors suggest Jupiter acted as an early barrier: its rapid growth opened a gap in the protoplanetary disc and would have prevented most outer material from reaching the inner region. The researchers describe their work as data‑driven and say they will investigate why the hot inner system contained enough water and whether similar processes occur in exoplanet systems.
Difficult words
- isotope — Atoms of the same element with different massIsotopes
- isotopic — Describing differences in atomic mass measurements
- reservoir — A region storing material in a planetary system
- protoplanetary — Relating to the disc where planets form
- barrier — Something that blocks movement or flow
- meteorite — A rock from space that reaches Earthmeteorites
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What evidence and methods in the article convinced the researchers about an inner‑system origin for Earth? Explain briefly.
- If Jupiter acted as an early barrier, how could that change ideas about how Earth got its water? Give one or two possible explanations.
- How might studying other planetary systems (exoplanets) help test whether the processes described here are common?
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