September 13, 2022

Speaker: Robin Canup (Southwest Research Institute, Boulder)

Contact Information: robin@boulder.swri.edu

Title: Origin of the Moon: New Results and Open Issues

Abstract: A primary scientific outcome of the Apollo program was the giant impact theory for lunar origin, in which a collision at the end of Earth’s main accretionary phase creates a disk from which the Moon forms. In the past decade, the nature of a Moon-forming impact has become highly debated, driven by increasingly precise sample analyses that show that the Earth and Moon have essentially identical isotopic compositions across all non-volatile elements. Giant impacts usually produce disks that originate primarily from the impactor (“Theia”) rather than from the target protoearth. Meteorites that originate from Mars, and nearly all those from parent bodies in the asteroid belt, have quite different isotopic compositions than the Earth. If Theia had been similarly non-Earth like, and the pre-lunar disk originated primarily from Theia, one would then most naturally expect measurable differences between the Earth and Moon. Instead, they are indistinguishable across most elements. Many new scenarios have been proposed to resolve this fundamental dilemma, involving different Theia compositions, protolunar disk evolutions, and/or early Earth-Moon dynamical histories. I will discuss several of these, as well as key remaining uncertainties and prospects for relevant new constraints from future lunar exploration.

Visitor's room: Room 122

Visit Schedule:

Wednesday (14 Sep. 2022):

  • 9:30 a.m.: Jeremy Goodman (Peyton 129)

  • 10:00 a.m Robert Lupton (25C(?) -- the Rubin/PFS area near the loading dock)

  • 10:30 a.m.:

  • 11:00 a.m.: Yubo Su (Peyton 122)

  • 11:30 a.m.: Josh Winn (Peyton 125)

  • 12:00 p.m.: Wunch (Grand Central)

  • 12:30 p.m.: Wunch (Grand Central)

  • 1:00 p.m.: Jamie Sue Rankin (Peyton 122)

  • 1:30 p.m.: Peter Melchior (Peyton 131)

  • 2:00 p.m.: Michael Strauss (Peyton 113)

  • 2:30 p.m.: Jamie Rankin (Peyton 122)

  • 3:00 p.m.: Space Physics Group (171 Broadmead)

  • 3:30 p.m.: Space Physics Group (171 Broadmead)

  • 4:00 p.m.: Space Physics Group (171 Broadmead)

  • 4:30 p.m.:

  • 5:00 p.m.:


Dinner Sign-up - add your name here:

Wednesday (14 Sep. 2022)

  1. Robin Canup

  2. Faculty Host: Robert Lupton

  3. Postdoc Host: Yubo Su

  4. Josh Winn

  5. Erin Flowers

  6. Roberto Tejada Arevalo

  7. Rodrigo Cordova

  8. Jamie Rankin

STUDENTS HAVE PRIORITY. .

PLEASE NO MORE THAN 8 PEOPLE (it is more difficult to properly interact with the speaker in larger groups).