Secrets of the Sun

It contains 99.9 percent of all the matter in our solar system and sheds hot plasma at nearly a million miles an hour. The temperature at its core is a staggering 27 million degrees Fahrenheit. It convulses, it blazes, it sings. You know it as the sun.

Scientists know it as one of the most amazing physics laboratories in the universe. Now, with the help of new spacecraft and Earth-based telescopes, scientists are seeing the sun as they never have before and even recreating what happens at its very center in labs here on Earth. Their work will help us understand aspects of the sun that have puzzled scientists for decades.

But more critically, it may help us predict and track solar storms that have the power to zap our power grid, shut down telecommunications, and ground global air travel for days, weeks, or even longer. Such storms have happened before—but never in the modern era of satellite communication. “Secrets of the Sun” reveals a bright new dawn in our understanding of our nearest star—one that might help keep our planet from going dark. Watch below on PBS or on YouTube.

Watch Secrets of the Sun on PBS. See more from NOVA.

Earth Revealed

This series shows the physical processes and human activities that shape our planet. From earthquakes and volcanoes to the creation of sea-floor crusts and shifting river courses, Earth Revealed offers stunning visuals that explain plate tectonics and other geologic concepts and principles. Follow geologists in the field as they explore the primal forces of the Earth. This series can also be used as a resource for teacher professional development. Due to licensing agreements, online viewing of the videos for this resource is restricted to network connections in the United States and Canada. View episodes from the homepage.

1. Down to Earth
Surface conditions of the planets Venus and Mars are compared with those of Earth, and scenes of Earth’s living landscapes lead into a discussion of how unique Earth truly is. Major topics addressed in the series, including plate tectonics, natural resources, seismology, and erosion, are introduced in this program.

2. The Restless Planet
Early Greek astronomers believed that Earth was the center of the universe. However, this notion changed dramatically over time, especially after the invention of the telescope. This program traces the development of astronomical theory with discussions of the discoveries of Copernicus, Galileo, Kepler, and Newton. Unique characteristics of Earth are also discussed.

3. Earth’s Interior
Oil wells do more than just produce oil — they serve as windows to Earth’s interior. This program introduces the topic of geophysics, exploring methods of studying what lies beneath Earth’s surface. Geophysicists use seismic wave studies, variations in temperature, magnetic fields, gravity, and computer simulations to create models of deep structures.

4. The Sea Floor
The mysteries of the ocean floor lie hidden under enormous pressure and total darkness. This program looks at the research submersibles and indirect methods used to study the bottom of the sea, providing a glimpse of volcanic activity, formations such as the continental shelf and mid-ocean ridges, and life forms that thrive at extreme depths.

5. The Birth of a Theory
In the 1960s, earth scientists developed the theory of plate tectonics. This program traces the development of plate tectonics, beginning with the contributions and methods of geologist Alfred Wegener. Sea-floor spreading, continental drift, paleomagnetism, and the primordial supercontinent Pangaea are some of the topics covered.

6. Plate Dynamics
This program examines the movement and interaction of tectonic plates, which account for a vast array of geologic formations and phenomena — from California’s San Andreas Fault to the Rift Valley of eastern Africa. The program covers convergent boundaries, subduction, hotspots, and the debate over what drives plate motion.

7. Mountain Building
This program erodes the myth of the mountain as a solid, permanent structure. Animations are used to illustrate the process of orogeny (mountain building) through accretion and erosion, as well as the role of plate tectonics, the rock cycle, and how different types of rock are formed in the course of mountain building.

8. Earth’s Structures
A visit to the Grand Canyon lays the foundation for this exploration of rock layers and deformation. The program covers sedimentation, major structures, the methods used to examine them, and how petroleum may be trapped inside them. It also looks at tectonic force and the different types of stress involved in the formation of geologic structures.

9. Earthquakes
Showing actual footage of earthquakes and their aftermath, this program discusses the forces that fuel these massive events. Faults, waves, and the transfer of energy from the epicenter are explained, and histories of the seismograph and Richter scale are presented. The program also describes devices being developed to study — and eventually predict — earthquakes.

10. Geologic Time
To illustrate the immensity of geologic time, the entire span of Earth’s existence is compressed down to a year. The timeline of major geologic events is superimposed onto the year for a condensed view of Earth’s evolution. A relationship between this timeline and that of life on Earth is established, with fossils and radiocarbon dating playing a major role in the discovery.

11. Evolution Through Time
The fossil record reveals much about the diversity and development of species. This program examines the traces left by early plants, animals, and single-celled organisms and follows the progression of life forms over time. Connections are drawn between atmospheric gases, climate change, rock formation, biological functions, and mass extinctions.

12. Minerals: The Materials of Earth
Minerals have been indispensable to human civilization. This program looks at the variety of minerals, their atomic and crystalline structures, and their physical properties such as hardness and luster. Petrologists’ methods of sectioning rocks are shown, and gems, precious metals, ore excavation, and the value of silicates are discussed.

13. Volcanism
Volcanoes provide clues about what is going on inside Earth. Animations illustrate volcanic processes and how plate boundaries are related to volcanism. The program also surveys the various types of eruptions, craters, cones and vents, lava domes, magma, and volcanic rock. The 1980 eruption of Mount St. Helens serves as one example.

14. Intrusive Igneous Rocks
Most magma does not extrude onto Earth’s surface but cools slowly deep inside Earth. This magma seeps into crevices in existing rock to form intrusive igneous rocks. Experts provide a graphic illustration of this process and explain the types and textures of rocks such as granite, obsidian, and quartz. Once again, plate tectonics is shown to be involved in the process.

15. Weathering and Soils
The Cleopatra’s Needle obelisk in New York City’s Central Park is severely weathered after only 75 years, whereas the dry climate of Egypt has preserved similar structures in that country for millennia. This program shows how weather, climate, chemicals, temperature, and type of substrate factor into rock and soil erosion. Environmental connections are also considered.

16. Mass Wasting
Anyone undertaking a building project must understand mass wasting — the downslope movement of earth under the influence of gravity. Various factors in mass wasting, including the rock’s effective strength and pore spaces, are discussed, as are different types of mass wasting such as creep, slump, and landslides. Images of an actual landslide illustrate the phenomenon.

17. Sedimentary Rocks: The Key to Past Environments
This program returns to the Grand Canyon: its exposed layers of sedimentary rock allow scientists to peer into the geologic past. The movement of sediment and its deposition are covered, and the processes of lithification, compaction, and cementation that produce sedimentary rocks are explained. Organic components of rock are also discussed.

18. Metamorphic Rocks
The weight of a mountain creates enough pressure to recrystallize rock, thus creating metamorphic rocks. This program outlines the recrystallization process and the types of rock it can create — from claystone and slate to schist and garnet-bearing gneiss. The relationship of metamorphic rock to plate tectonics is also covered.

19. Running Water I: Rivers, Erosion and Deposition
Rivers are the most common land feature on Earth and play a vital role in the sculpting of land. This program shows landscapes formed by rivers, the various types of rivers, the basic parts of a river, and how characteristics of rivers — their slope, channel, and discharge — erode and build the surrounding terrain. Aspects of flooding are also discussed.

20. Running Water II: Landscape Evolution
The Colorado River is a powerful geologic agent — powerful enough to have carved the Grand Canyon. This program focuses on how such carving takes place over time, looking at erosion and deposition processes as they relate to river characteristics and type of rock. The evolution of rivers is covered, along with efforts to prevent harmful consequences to humans.

21. Groundwater
Approximately three-quarters of Earth’s surface is covered by water. But most fresh water comes from underground. Topics of this program include aquifers, rock porosity and permeability, artesian wells, the water table, cave formation, sinkholes, and how groundwater may become contaminated.

22. Wind, Dust and Deserts
Land in arid climates is shaped in particular ways. This program shows how deserts are defined by infrequent precipitation and how desertification relates to proximity to the equator, proximity to mountains, and ultimately plate tectonics. Images of landscapes illustrate how wind creates features such as dunes, playas, blow-outs, and even oases.

23. Glaciers
Many of the world’s most beautiful landscapes were made by glaciers. This program shows how, explaining glacial formation, structure, movement, and methods of gouging and accumulating earth. The program provides images of glaciers and glacial landforms such as moraines, and discusses how study of glaciers may help us understand ice ages and the greenhouse effect.

24. Waves, Beaches and Coasts
This program shows the dynamic interaction of two geologic agents: rocky landmasses and the energy of the ocean. Aspects of waves — their types, parts, movement, and impact on the shore — are illustrated. The program also covers shoreline characteristics, currents, sea barriers, tides, and how the greenhouse effect could impact sea level and coastal lands.

25. Living With Earth, Part I
Scenes of San Francisco before the Loma Prieta earthquake introduce this program addressing how humans are learning to cope with earthquakes. Various groups and agencies are studying the San Andreas Fault and the damage caused along its path to better understand how earthquakes ravage the land. Methods of studying earthquakes are reviewed.

26. Living With Earth, Part II
Since the nineteenth century, humans have turned to the Earth for energy sources to fuel their industry. This program discusses where oil comes from, how it is extracted, and how it is converted into energy. The effects of oil drilling and the burning of fossil fuels are also addressed, and the potential of alternative energy sources is considered.

Planet Earth

This series presents visually spectacular tours of the seven continents as it makes connections between our solar system and Earth’s oceans, climate, and mineral and energy sources. It unifies Earth science, astronomy, and comparative planetology into an integrated discipline that relies on common scientific methods. A flexible instructional resource, Planet Earth provides course material for nonscience students and science majors. Produced by WQED/Pittsburgh in association with the National Academy of Sciences. 1986.

1. The Living Machine
Plate tectonics, one of the most important discoveries of the 20th century, is explored at such sites as the erupting Kilauea volcano and the bottom of the Atlantic Ocean in the submersible craft Alvin.

2. The Blue Planet
Perhaps the last great unexplored frontier on earth, the oceans reveal major new revelations as detected by scientists aboard the space shuttle and submerged to the depths of the “middle ocean” to view rare life forms.

3. The Climate Puzzle
Scientists piece together an unfolding mystery — what caused the ice ages, how Venus’s greenhouse effect may have parallels on earth, and what Antarctica’s eerie ice rivers demonstrate.

4. Tales From Other Worlds
Through little-seen footage shot in space and special effects, visit the great failed star of Jupiter, probe the raging volcano of Io, and peer through acid rain clouds to see the surface of Venus for the first time.

5. Gifts From the Earth
By examining the earth’s mineral and energy sources, scientists analyze how the theory of plate tectonics has revolutionized the search for earth’s treasures that lie hidden in locations such as the Red Sea and Antarctic ice cap.

6. The Solar Sea
Geologists investigate an 800-million-year-old rock record of sun activity in an ancient Australian lake bed, and fabulous ground and satellite photography of the aurora borealis all contribute to an understanding of earth’s relationship to the yellow dwarf star we know as the sun.

7. Fate of the Earth
New theories about the global consequences of a “nuclear winter” and an “ultra-violet spring” are revealed in this final episode that explores the role of life in shaping earth and its future.