1.
The Sun's Power
(02:03)
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The Sun's story begins 13 billion years ago when in an instant the universe was born in the Big Bang. The Sun powers all of Earth's natural systems and sustains every plant and animal; all life on Earth owes its existence to the Sun.
2.
Winter Solstice at Maeshowe
(03:44)
Remnants from a Stone Age civilization cover Scotland's Orkney Islands. At sunset on the winter solstice sunlight shines straight up the entrance tunnel and illuminates the interior of Maeshowe, a Neolithic chambered tomb.
3.
Measuring the Sun's Power
(05:14)
Modern solar observatories view the Sun's turbulent, constantly changing surface. Scientists devise ways to probe the Sun's interior and calculate the amount of energy the Sun produces.
4.
What Powers the Sun?
(04:58)
Scientists did not understand how the Sun works until the middle of the 20th century. The Sun is made mostly of hydrogen, the simplest and most abundant element in the universe; the Sun's power relies on this gas.
5.
Birth of a Star: Studying Nebulae to Understand the Sun
(03:54)
Scientists study nebulae to understand the stages in which stars, including the Sun, and solar systems are made. A star comes to life with a burst of fusion that liberates so much energy that the star begins to shine within minutes.
6.
Hydrogen and the Sun's Energy
(02:35)
Every atom was made in the heart of a star, and all were made using the simplest element, hydrogen, as the starting ingredient. The Sun has been burning for five billion years; five million tons of the Sun is converted to pure energy every second.
7.
The Power of Nuclear Fusion
(04:10)
The hydrogen bomb is a man-made version of the process that powers the Sun. Controlled nuclear fusion could solve the world's energy problems; after decades of trying, scientists believe they are close to creating the Sun's power on Earth.
8.
Seasonal Affective Disorder
(04:31)
Many people associate the Sun's warmth with feelings of happiness, but research shows it is exposure to light that elevates moods. Seasonal Affective Disorder (SAD) is a depressive illness that strikes during short winter days. A village in Austria gets no direct sunlight between November and February.
9.
Sunspots
(04:10)
Galileo's observations of sunspots led to his discovery that the Sun rotates, and that it turns faster at its equator than at its poles. For centuries people have suspected sunspots affect the Earth, but how they do so remained largely a mystery.
10.
Effects of Sunspots on Climate: The Little Ice Age
(02:08)
Sunspots have a real, though subtle, effect on Earth's climate. At a time when sunspots disappeared for 70 years, from 1645 to 1715, the northern hemisphere experienced its last period of prolonged cold, a time called "the Little Ice Age."
11.
Viewing the Sun from Space
(04:07)
Skylab astronauts of the 1970s witnessed displays of solar power previously unseen by anyone. Since then scientists have launched several space telescopes to study the Sun; the most used of these is SOHO, the Solar and Heliospheric Observatory.
12.
Sunspots, Solar Flares, and the Sun's Magnetic Fields
(04:42)
Solar flares and coronal mass ejections erupt from the hearts of sunspots; solar flare activity peaks every 11 years. Solar astronomers have learned these explosions are not caused by fusion, but by the Sun's magnetic fields.
13.
Space Weather
(03:47)
Space weather, like the magical dancing lights of the auroras, is created when particles from solar storms meet Earth's magnetic field. Space weather is known to disrupt wildlife and to interfere with satellites and communications systems.
14.
Global Warming, Solar Power, and the Energy Crisis
(05:12)
The greenhouse effect could be stopped by harnessing the Sun's heat. Hopi Indians use solar power to live sustainably with their environment; new technology enables development of cost effective, large-scale solar power systems.
15.
Death of the Sun and Earth
(02:11)
In about five billion years the Sun will run out of hydrogen, become a red giant, die, and take Earth with it. The solar system will become dark and in a last gasp the Sun will blow its remaining gas into space.