Ideas worth spreading

Where did the Moon come from? A new theory

3,175,976 views | Sarah T. Stewart • TED Salon: U.S. Air Force

The Earth and Moon are like identical twins, made up of the exact same materials -- which is really strange, since no other celestial bodies we know of share this kind of chemical relationship. What's responsible for this special connection? Looking for an answer, planetary scientist and MacArthur "Genius" Sarah T. Stewart discovered a new kind of astronomical object -- a synestia -- and a new way to solve the mystery of the Moon's origin.

The Earth and Moon are like identical twins, made up of the exact same materials -- which is really strange, since no other celestial bodies we know of share this kind of chemical relationship. What's responsible for this special connection? Looking for an answer, planetary scientist and MacArthur "Genius" Sarah T. Stewart discovered a new kind of astronomical object -- a synestia -- and a new way to solve the mystery of the Moon's origin.

This talk was presented at a TED Salon event given in partnership with U.S. Air Force. TED's editors chose to feature it for you.

Read more about TED Salons.

Support space exploration. Humans are destined to explore outer space. Learn about the Apollo missions and the science arguments for why we should return to the Moon and go to Mars. Join the Planetary Society to learn about and support space exploration.

About the speaker

Sarah T. Stewart

Sarah T. Stewart

Planetary scientist

See speaker profile

Sarah T. Stewart specializes in the study of collisions in the solar system.

Rebecca Boyle | Quanta Magazine, 2017 | Article

"What Made the Moon? New Ideas Try to Rescue a Troubled Theory"

Rebecca Boyle opens the door to the great debates around the origin of the Moon and how scientists try out and test new ideas.

David J. Stevenson | Physics Today, 2014 | Article

"Making the Moon"

Many stories for the origin of the Moon are fantastical. Our modern story of a giant impact is tested with physics and chemistry. The giant impact theory does not explain all the observations, and the true answer to the origin of the Moon may require a clever new idea or changing our thinking about how Earth was formed.

UC Davis | YouTube, 2018 | Watch

"Shock Compression Lab"

Sometimes the most useful tools are unexpected. Sarah Stewart explains how huge cannons are used to study the early history of our Solar System.

Simon J. Lock, Sarah T. Stewart, Michail I. Petaev, Zoe M. Leinhardt, Mia T. Mace, Stein B. Jacobsen, Matija Ćuk | Journal of Geophysical Research, 2018 | Article

"The origin of the Moon within a terrestrial synestia"

Simon Lock and colleagues present a new idea for making the Moon within the Earth after the Earth was transformed by a giant impact into a new type of astronomical object, called a synestia.

About TED Salon

TED Salons welcome an intimate audience for an afternoon or evening of highly-curated TED Talks revolving around a globally relevant theme. A condensed version of a TED flagship conference, they are distinct in their brevity, opportunities for conversation, and heightened interaction between the speaker and audience.

Read more about TED Salons

This talk was presented at a TED Salon event given in partnership with U.S. Air Force. TED's editors chose to feature it for you.

Read more about TED Salons.

Support space exploration. Humans are destined to explore outer space. Learn about the Apollo missions and the science arguments for why we should return to the Moon and go to Mars. Join the Planetary Society to learn about and support space exploration.