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Early Earth Bombarded by Comets

  • Posted 08.28.14
  • NOVA

Key ingredients for life may have been delivered throughout the solar system by comets and asteroids billions of years ago. The gravitational interactions of Jupiter and Saturn could have destabilized the early solar system, leading to a period in which comets and asteroids collided with objects throughout the solar system (including the early Earth). Impact craters visible on moons and planets may be evidence of this period.

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Launch Video Running Time: 05:10

Transcript

NARRATOR: But what could cause comets to fly in from the furthest edges of the solar system, slam into Earth, and deliver these organic compounds?

The clues to one possible process lie back out in the Kuiper Belt, the disk of icy objects that orbits the sun at the edge of our solar system.

HAL LEVISON: We expected, when we found the Kuiper Belt, that we would just see objects in nice circular orbits about the sun.

NARRATOR: But observations reveal that the Kuiper Belt objects are not orbiting as predicted. Out here, it's chaotic.

HAL LEVISON: When we look at the Kuiper Belt, we see something that looks like somebody took the solar system, picked it up and shook it real hard. And that's what started us thinking that something really strange had happened there.

NARRATOR: Levison theorizes that the reason for this mayhem likely is connected with the two largest planets in the solar system. Jupiter is so big, it could swallow more than 1,300 Earths, and Saturn, with its vast rings of ice is 95-times Earth's mass. With their enormous size comes an enormous gravitational pull.

HAL LEVISON (Astrophysicist, Southwest Research Institute): Everything that we see is a result of what Jupiter and Saturn did.

NARRATOR: Levison wonders if the chaos of the Kuiper Belt could have resulted from a planet smashing into it. To find out, he runs a number of computer simulations.

One model creates the conditions in the Kuiper Belt that we see today. Three-point-nine-billion years ago, as Jupiter circled the sun twice, Saturn made one complete orbit. Each time these orbits coincided, there was a powerful gravitational surge that pushed Saturn's orbit further from the sun and destabilized the orbits of the two outermost planets, Uranus and Neptune.

HAL LEVISON: Jupiter and Saturn sort of tugged each other, and that drove the orbits of Uranus and Neptune absolutely nuts.

NARRATOR: Uranus and Neptune are sent careering outwards towards the Kuiper Belt. Comets, ranging in size from a mile across to objects the size of Pluto, are blasted out of their orbits by the planetary invasion.

HAL LEVISON: The disk went kaplooey! Think of it as sort of a bowling ball hitting bowling pins. These things got scattered all over the place.

NARRATOR: The end result is a hundred-million-year period when comets, kicked out into the solar system by Uranus and Neptune, smash into anything in their path.

It's a period scientists call "the late heavy bombardment."

Earth doesn't escape.

HAL LEVISON: This was so violent that, probably, every square inch of the surface of the earth was hit by a comet during this time.

NARRATOR: This is one theory that might explain how massive amounts of organic molecules, the building blocks of life, made their way to Earth.

Possible evidence of the late heavy bombardment can be seen on the surface of other planets and moons in the solar system: impact craters.

DANNY GLAVIN: Literally the seeds of life, the amino acids, would have been delivered to all the planets and their moons in our solar system.

NARRATOR: So if life's building blocks were delivered by comets throughout the solar system, could life also have sprung up on worlds other than Earth?

Credits

FINDING LIFE BEYOND EARTH: ARE WE ALONE?

Written, Produced and Directed by
Oliver Twinch

Produced in cooperation with NASA and the National Institute of Aerospace

ASSISTANT PRODUCER
Alexis Burke
EDITED BY
Mairin O’Faolain
Dudley Sargeant
Nigel Barker
CAMERA
Jonathan Dacey
NARRATED BY
Jay O. Sanders
SOUND RECORDISTS
Percy Urgena
Gregg Hinnen
Haven McKinney
MUSIC
Universal Audio Network
VISUAL EFFECTS
Prime Focus
VISUAL EFFECTS SUPERVISOR FOR PRIME FOCUS
Simon Clarke
VISUAL EFFECTS LINE PRODUCER FOR PRIME FOCUS
Vikas Gandhi
VISUAL EFFECTS ASSISTANT PRODUCER FOR DARLOW SMITHSON PRODUCTIONS
Andrew Ryder
ONLINE EDITOR
Alan Jones
COLORIST
Blair Wallace
AUDIO MIX
Danny Finn
PROGRAM ADVISORS
Jim Bell David Grinspoon
ARCHIVE RESEARCH
Paul Gardner
James Labous
RESEARCH
Eloisa Noble
Faran Ismailpour
PRODUCTION COORDINATOR
Julia Speed
LINE PRODUCER
Ann Hampsey
ARCHIVAL MATERIAL
ASI
ASU
BBC Motion Gallery
Caltech
Carnegie Institution of Washington
Cassini Radar Team
Cornell University
ESA
ESO
Footage Vault
Gemini Observatory/AURA
Harvard University
HiRISE Imaging Team
Honeybee Robotics
Hubble
JAXA/Hayabusa Dome Movie Production Committee
JHU APL
Kennedy Space Center
NASA
NASA/Goddard Space Flight Center
NASA/JPL
Space Science Institute
Texas A&M University
The Institute for Solar Physics
University of Arizona
University of Rome
USGS
Washington University in St. Louis
SPECIAL THANKS
Southwest Research Institute
Caltech
Chris Abbas
David Chapman
Richard Kraus
Sarah Stewart
W. M. Keck Observatory
Harvard University
McGill University
Jacqueline Goordial
Lyle Whyte

FOR DARLOW SMITHSON PRODUCTIONS

DIRECTOR OF OPERATIONS
Ulla Streib
EXECUTIVE PRODUCER
Ben Bowie
NOVA SERIES GRAPHICS
yU + co.
NOVA THEME MUSIC
Walter Werzowa
John Luker
Musikvergnuegen, Inc.
ADDITIONAL NOVA THEME MUSIC
Ray Loring
Rob Morsberger
POST PRODUCTION ONLINE EDITOR
Spencer Gentry
CLOSED CAPTIONING
The Caption Center
MARKETING AND PUBLICITY
Karen Laverty
PUBLICITY
Eileen Campion
Victoria Louie
SENIOR RESEARCHER
Kate Becker
NOVA ADMINISTRATOR
Kristen Sommerhalter
PRODUCTION COORDINATOR
Linda Callahan
PARALEGAL
Sarah Erlandson
TALENT RELATIONS
Scott Kardel, Esq.
Janice Flood
LEGAL COUNSEL
Susan Rosen
DIGITAL PROJECTS MANAGER
Kristine Allington
DIRECTOR OF NEW MEDIA
Lauren Aguirre
ASSOCIATE PRODUCER
POST PRODUCTION Patrick Carey
POST PRODUCTION EDITOR
Rebecca Nieto
POST PRODUCTION MANAGER
Nathan Gunner
COMPLIANCE MANAGER
Linzy Emery
DEVELOPMENT PRODUCERS
Pamela Rosenstein David Condon
SUPERVISING PRODUCER
Stephen Sweigart
BUSINESS AND PRODUCTION MANAGER
Jonathan Loewald
SENIOR PRODUCER AND PROJECT DIRECTOR
Lisa Mirowitz
COORDINATING PRODUCER
Laurie Cahalane
SENIOR SCIENCE EDITOR
Evan Hadingham
SENIOR SERIES PRODUCER
Melanie Wallace
EXECUTIVE PRODUCER
Howard Swartz
MANAGING DIRECTOR
Alan Ritsko
SENIOR EXECUTIVE PRODUCER
Paula S. Apsell

A NOVA Production by Darlow Smithson Productions

© 2011 WGBH Educational Foundation All rights reserved

This material is based on work supported by National Aeronautics and Space Administration, Langley Research Center under the Research Cooperative Agreement No. NNL09AA00A awarded to the National Institute of Aerospace. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of National Aeronautics and Space Administration, Langley Research Center or the National Institute of Aerospace.

FINDING LIFE BEYOND EARTH: MOONS AND BEYOND

Written, Produced and Directed by
Oliver Twinch

Produced in cooperation with NASA and the National Institute of Aerospace

ASSISTANT PRODUCERS
Alexis Burke
Dominic Aston
EDITED BY
Mairin O’Faolain
Jason Savage
Nigel Barker
CAMERA
Jonathan Dacey
NARRATED BY
Jay O. Sanders
SOUND RECORDISTS
Percy Urgena
Gregg Hinnen
Haven McKinney
Pandora Kronenburg
MUSIC
Universal Audio Network
VISUAL EFFECTS
Prime Focus
VISUAL EFFECTS SUPERVISOR FOR PRIME FOCUS
Simon Clarke
VISUAL EFFECTS LINE PRODUCER FOR PRIME FOCUS
Vikas Gandhi
VISUAL EFFECTS ASSISTANT PRODUCER FOR DARLOW SMITHSON PRODUCTIONS
Andrew Ryder
ONLINE EDITOR
Alan Jones
COLORIST
Blair Wallace
AUDIO MIX
Danny Finn
PROGRAM ADVISORS
Jim Bell
David Grinspoon
ARCHIVE RESEARCH
Paul Gardner
James Labous
RESEARCH
Eloisa Noble
Faran Ismailpour
PRODUCTION COORDINATOR
Julia Speed
LINE PRODUCER
Ann Hampsey
ARCHIVAL MATERIAL
Artbeats
BBC Motion Gallery
Corbis
Getty
Joseph Resing/NOAA
Footage Vault
Woods Hole Oceanographic Institution
NASA
NASA/JPL
Caltech
NASA/Goddard Space Flight Center
Southwest Research Institute
Eastbay Astronomical Society
Cassini Radar Team
ESA
Hubble
ASI
ESO
Gemini Observatory/AURA
Max-Planck-Institute for Astronomy
Rice University
STScI
University of Arizona
DLR
ASU
JHU APL
GSFC
Space Science Institute
Universities Space Research Association
Lunar & Planetary Institute
University of Colorado
USGS
NCSA/MSU/UC San Diego
Swedish Solar Telescope / L. Rouppe van der Voort (University of Oslo)
The Institute for Solar Physics
Hawaii Institute of Geophysics and Planetology
SPECIAL THANKS
YMCA Snow Mountain Ranch
Space Telescope Science Institute
Chris Abbas
Emily Lakdawalla
Charles Fisher
Penn State University
Linda Amaral Zettler
Marine Biological Laboratory

FOR DARLOW SMITHSON PRODUCTIONS

DIRECTOR OF OPERATIONS
Ulla Streib
EXECUTIVE PRODUCER
Ben Bowie
NOVA SERIES GRAPHICS
yU + co.
NOVA THEME MUSIC
Walter Werzowa
John Luker
Musikvergnuegen, Inc.
ADDITIONAL NOVA THEME MUSIC
Ray Loring
Rob Morsberger
POST PRODUCTION ONLINE EDITOR
Spencer Gentry
CLOSED CAPTIONING
The Caption Center
MARKETING AND PUBLICITY
Karen Laverty
PUBLICITY
Eileen Campion
Victoria Louie
SENIOR RESEARCHER
Kate Becker
NOVA ADMINISTRATOR
Kristen Sommerhalter
PRODUCTION COORDINATOR
Linda Callahan
PARALEGAL
Sarah Erlandson
TALENT RELATIONS
Scott Kardel, Esq.
Janice Flood
LEGAL COUNSEL
Susan Rosen
DIGITAL PROJECTS MANAGER
Kristine Allington
DIRECTOR OF NEW MEDIA
Lauren Aguirre
ASSOCIATE PRODUCER POST PRODUCTION
Patrick Carey
POST PRODUCTION EDITOR
Rebecca Nieto
POST PRODUCTION MANAGER
Nathan Gunner
COMPLIANCE MANAGER
Linzy Emery
DEVELOPMENT PRODUCERS
Pamela Rosenstein
David Condon
SUPERVISING PRODUCER
Stephen Sweigart
BUSINESS AND PRODUCTION MANAGER
Jonathan Loewald
SENIOR PRODUCER AND PROJECT DIRECTOR
Lisa Mirowitz
COORDINATING PRODUCER
Laurie Cahalane
SENIOR SCIENCE EDITOR
Evan Hadingham
SENIOR SERIES PRODUCER
Melanie Wallace
EXECUTIVE PRODUCER
Howard Swartz
MANAGING DIRECTOR
Alan Ritsko
SENIOR EXECUTIVE PRODUCER
Paula S. Apsell

A NOVA Production by Darlow Smithson Productions

© 2011 WGBH Educational Foundation All rights reserved

This material is based on work supported by National Aeronautics and Space Administration, Langley Research Center under the Research Cooperative Agreement No. NNL09AA00A awarded to the National Institute of Aerospace. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of National Aeronautics and Space Administration, Langley Research Center or the National Institute of Aerospace.

IMAGE:

Image credit: Still from "Finding Life Beyond Earth" (incoming comet)
© WGBH Educational Foundation 2014

This is an excerpt from the NOVA program "Finding Life Beyond Earth."

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