1 / 12

Formation of our Moon: The Giant Impact Hypothesis

Formation of our Moon: The Giant Impact Hypothesis. Michelle Kirchoff Southwest Research Institute Center for Lunar Origin and Evolution. Southwest Research Institute in Boulder. http:// www.boulder.swri.edu /. Center for Lunar Origin and Evolution (CLOE).

adia
Télécharger la présentation

Formation of our Moon: The Giant Impact Hypothesis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Formation of our Moon: The Giant Impact Hypothesis Michelle Kirchoff Southwest Research Institute Center for Lunar Origin and Evolution

  2. Southwest Research Institute in Boulder http://www.boulder.swri.edu/

  3. Center for Lunar Origin and Evolution (CLOE) Goal: Learn more about how our Moon formed and changed in its early history • History of Impacts on Our Moon • Late heavy bombardment (many large basins forming in a short time) -> “Nice” model or end of accretion?

  4. Center for Lunar Origin and Evolution (CLOE) Goal: Learn more about how our Moon formed and changed in its early history • History of Impacts on Our Moon • Late heavy bombardment (many large basins forming in a short time) -> “Nice” model or end of accretion?

  5. Center for Lunar Origin and Evolution (CLOE) Goal: Learn more about how our Moon formed and changed in its early history • History of Impacts on Our Moon • explore different rates of impacts • Computer models constrained by new information about evolution of comet and asteroid populations • Analyze chemistries and ages of early Earth and Moon rocks • Analyze new images of Moon's surface to create a timeline of impact craters • Formation of Our Moon: Giant Impact Theory • How the disk evolved into the Moon we see today • Study physics of the disk -> motion, temperature • Powerful computer models constrained by information about chemistry of early Earth and Moon rocks

  6. http://cloe.boulder.swri.edu/

  7. Properties of the Moon • Mass ratio of Earth to Moon -> large moon • Moon formed near a rapidly-rotating Earth -> 5 vs. 24 hours • Moon is depleted in iron

  8. Giant Impact Model of Moon Formation Mars-sized body hits Earth obliquely & Moon forms from debris disk Impactor Trajectory Early Earth • This model explains: • Mass ratio Earth-Moon • Earth fast rotation speed • Lack of iron in Moon Iron core / stony mantle Animation from Robin Canup

  9. Temperature > 11,000° 10411,000° 9100 10,000° 8200 9100° 7100 8200° 6200 7100° 5100 6200° 4200 5100° 3100 4200° Animation from Robin Canup

  10. Large impacts are common! Very Elongated Sea of bodies: • Moon to Mars-sized • smaller planetesimals • Many Collisions Location of Asteroid Belt Elongation of Orbit Jupiter Very Circular Distance From Sun (Closer) (Further) Animation from Alessandro Morbidelli

  11. Lunar Accretion Simulations • Models allow us to track disk particles forming into Moon • The Moon could form in as short as a few years or as long as 10,000 years

  12. Issues • Moon forms too fast and hot => completely molten • oxide, siderophile, and volatile ratios different than expected (e.g., water!) • diversity of basalts • crust too thin • global cracks from cooling • New computer model • Late veneer • ~ 80% of material from impactor, but Earth-Moon oxygen isotope ratios identical

More Related