NOVA: ORIGINS: EARTH IS BORN/HOW LIFE BEGAN {PARTS 1 & 2 OF 4} (TV)

Summary

Two episodes in this series of science documentaries. This mini-series, hosted by astrophysicist Neil deGrasse Tyson, examines the formation of Earth, the beginnings of life on the planet, if humans are alone in the universe, and the Big Bang theory.

In episode one, "Earth Is Born," the planet is first depicted as "a primeval hell," composed chiefly of noxious gas-spewing volcanoes and continuous lava flows. Walking through Times Square, Tyson questions how Earth became a habitable planet.

Tyson then explains that, four and a half billion years ago, ancient supernovas exploded and collapsed into a star that ultimately became the sun. Dust grains circling the sun began to collide, becoming pebbles that -- through more collisions -- grew into rocks. As the larger rocks adopted a gravitational pull, they morphed into planetisimals, measuring a few miles across. The four largest became known as Mars, Mercury, Venus, and Earth.

Fragments of rock that broke free from an asteroid belt, commonly known as meteors, began colliding with Earth. According to NASA scientist Mike Zolensky, pieces of meteors -- like those recently found under an ice lake in British Columbia -- provide significant clues to Earth's origins.

As meteors and pieces of debris were drawn to Earth by its gravity, heat was generated which turned the planet's surface into a raging furnace. Earth's outer section became an ocean of magma, causing all traces of iron to sink and coalesce into a core that generated a magnetic field, complete with a north and south pole. The magnetic field also deflected particles from the solar wind, keeping Earth from turning into a barren desert like the surface of Mars.

As volcanoes continued to spew deadly gases on the Earth's surface, the moon was born. Bill Hartmann of the Planetary Science Institute tells how the rocks gathered from NASA's Apollo missions helped reveal the moon's origins. Hartmann theorizes that a large planetisimal plowed into Earth around fifty million years after its formation. As Earth's outer layers melted, the planetisimal and Earth fused; meanwhile, chunks of molten rock were sent into orbit that coalesced into the moon.

The moon's gravitational pull on Earth caused massive shifts on Earth's surface. In addition, Earth's axis to the sun was affected, causing a tilt that resulted in the changing seasons. While the molten surface cooled, a crust was formed which allowed water to collect. As volcanoes pumped steam into the atmosphere, the steam condensed into rain that pooled into growing expanses of water.

Other scientists believe that ice-bearing comets are the cause of Earth's oceans. Michael Mumma of NASA's Goddard Space Flight Center conducts an experiment to see if the chemical composition of "heavy water" in a typical comet matches that of ocean water. The test proves inconclusive. But regardless of how water first appeared, Tyson states that the template for life's existence on Earth was already in motion.

In episode two, "How Life Began," Mumma describes the surface of the Earth four billion years ago as having no resemblance to depictions of the Garden of Eden; Earth featured olive-green oceans, a burnt-orange sky, and no vegetation.

To explore conditions that might have been similar to that of early Earth, microbiologists Penny Boston and Diana Northrup travel to Cueva de Villa Luz, a massive cave in a rain forest in southern Mexico. There, donning gas masks to avoid the cave's poisonous hydrogen sulfide, the women find thriving colonies of single-celled bacteria which resemble drippy stalactite-like formations.

Next, Tyson explains how hydrogen, oxygen, carbon, and nitrogen are the ingredients for all forms of life. A theory that life began three billion, eight million years ago is supported by rocks from West Greenland that contain "chemical fingerprints" of microbes. Steven Mojzsis of the University of Colorado takes samples from the rocks that show carbon, as well as evidence of a biosphere on Earth.

Further experiments show that life may have initially come from space dust, or meteors. A chunk of a meteorite discovered in Australia in 1969 is shown to contain amino acids, "the building blocks of life." Jennifer Blank of the Lawrence Livermore National Laboratory conducts an experiment to simulate the effect of a comet crashing into Earth, and what materials could survive. She finds that, after impact, amino acids transform into more complex molecules, the kinds of proteins that form cells in the body.

Thinking that life may have begun underground, a team of scientists goes to South Africa and enters one of Earth's deepest mines to determine if microbes can survive in pitch darkness. They find that the organisms can live on a variety of gases. Next, the discovery of creatures that exist within volcanic vents on the ocean floor give rise to the theory that life may have begun under water.

Tyson tells how microbes, upon reaching Earth's surface, would take advantage of the sun, leading to the process of photosynthesis. Fossils in Western Australia -- thought to be the oldest fossils in the world -- verify the growth of microbes from three and a half billion years ago; nearby colonies of micro-organisms indicate how oxygen and iron ore likely originated.

As oxygen built up in Earth's atmosphere, the planet was slowly transformed, most significantly after a layer of ozone formed to screen out the sun's harmful radiation. The episode concludes as Tyson tells how multi-cellular life evolved, followed by fish, insects, reptiles, primates, and humans.

Contains two program-sponsored commercials and one promo.

Cataloging of this program was made possible by the Corporation for Public Broadcasting.

Details

• NETWORK: PBS
• DATE: September 28, 2004 8:00 PM
• RUNNING TIME: 1:48:07
• COLOR/B&W: Color
• CATALOG ID: 100372
• GENRE: Public affairs/Documentaries
• SUBJECT HEADING: Creation; Science
• SERIES RUN: PBS - TV series, 1974-
• COMMERCIALS:
  • TV - Commercials - Microsoft technologies
  • TV - Commercials - Sprint communications
  • TV - Promos - "Frontline"

CREDITS

• Paula S. Apsell … Executive Producer
• Thomas Levenson … Executive Producer
• Stuart Carter … Executive Producer
• Laurie Cahalane … Coordinating Producer
• Stephen Sweigart … Supervising Producer
• Alice Harper … Producer, Director, Writer
• Joseph McMaster … Producer, Writer
• Susanne Simpson … Producer
• Julie Crawford … Associate Producer
• Caroline Penry-Davey … Associate Producer
• Nathan Gunner … Associate Producer
• Martin Mortimore … Series Producer
• Melanie Wallace … Series Producer
• Mark Everest … Segment Director
• Tony Lee … Animation
• Nigel Henbest … Writer
• Rob Morsberger … Music by
• Richard Atree … Music by
• Mason Daring … Theme Music by
• Martin Brody … Theme Music by
• Michael Whalen … Theme Music by
• Neil deGrasse Tyson … Host, Narrator
• Jennifer Blank
• Penny Boston
• Bill Hartmann
• Stephen Mojzsis
• Michael Mumma
• Diana Northrup
• Mike Zolensky