Is the “Giant Impact Hypothesis” still considered to be the best explanation for how the moon came into being?

Yes.  The current experiments and modeling efforts predominantly use the giant impact hypothesis as the basis of their studies.  In other words, approximately 4.5 billion years ago, a collision of the early Earth with a Mars-sized object resulted in the formation of the Earth/Moon system.  This model provides answers to the reasons behind the Earth/Moon high-spin system, the low density of the Moon, and lunar composition.  Other hypothesis on lunar formation are that a planetoid (the Moon) was captures in the Earth’s gravity well, or that the Earth and Moon co-formed together through accretion.  Neither of these explanations provide quite the full picture that the giant impact does, however.

Brad Bailey

NLSI Staff Scientist

January 20, 2009

Carbon Workshop

NESF 2018

ELS 2018

Lunar Landing Workshop

Upcoming Events

February 2018


- Women in Planetary Science and Exploration
Feb 17-18 (Toronto, Canada)

- Deep Space Gateway Workshop
Feb 27-March 1 (Denver, Colorado)

View More Upcoming
View Past Events

SSERVI Science Teams

  • The new Moon

    6-6-17_moon

    Recent findings are challenging much of what we thought we knew about Earth’s nearest neighbor.

Did you know?

Moonquakes have been measured by seismometers emplaced by the Apollo astronauts.

Read More