The Moon’s origin shaped Earth’s early environment. About 4.5 billion years ago a massive object struck the young planet and debris later formed the Moon. Scientists call that destroyed object Theia. A new study by teams from the University of Chicago, the Max Planck Institute for Solar System Research, and the University of Hong Kong reports evidence about Theia’s composition; the results appear in Science.
The researchers used isotopes as clues. Isotopes are small variations of elements that act like fingerprints for where material formed in the early solar system. They measured iron with high precision and combined those results with earlier isotope data for chromium, calcium, titanium, molybdenum and zirconium from terrestrial rocks, Apollo lunar samples and meteorites.
Using models of metal movement during planet formation and impact simulations, the team concluded that Theia most likely formed closer to the Sun than Earth did and may have been a neighbor planet.
Difficult words
- origin — The point or cause where something begins.
- debris — Pieces left after a crash or break.
- isotope — Atom variant with different numbers of neutrons.isotopes
- composition — The parts or makeup of something.
- precision — The quality of being exact or very accurate.
- terrestrial — Relating to Earth or its land.
- meteorite — A space rock that reached Earth's surface.meteorites
- impact — A collision or strong effect on something.
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Why do you think scientists compare rocks from Earth, the Moon, and meteorites together?
- How could knowing where Theia formed change our view of Earth and the Moon?
- Would you be interested in studying space samples like Apollo lunar samples or meteorites? Why or why not?
Related articles
AI audio summaries of research can help — and err
Researchers tested Google’s NotebookLM, which turns research papers into podcast-style audio. The summaries were engaging and clearer for teaching, but every audio overview contained mistakes, so the authors advise reading the original papers to check claims.
