History's Mysteries

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The Misplaced Giant Planets
Investigate 51 Pegasi b, the first planet detected around a Sun-like star, which shocked astronomers by being roughly the size of Jupiter but in an orbit much closer to its star than Mercury is to the Sun. Probe the strange characteristics of these "hot Jupiters," which have turned up around…
The Art of Experiment
Learn how distances in the solar system were first determined. Then chart Henry Cavendish's historic experiment that found the value of Newton's gravitational constant. Cavendish's work allows almost everything in the universe to be weighed. Then see a confirmation of the equivalence principle, which says that gravitational and inertial mass…
Leonardo: A Dream of Flight
This is a film about Leonardo da Vinci (Brent Carver, Tony Award Winner) who was an Italian Renaissance man of many capabilities and gifts whose areas of interest included invention, painting, sculpting, architecture, science, music, mathematics, engineering, literature, anatomy, geology, astronomy, botany, writing, history, and cartography. The story begins in…
Stars in Their Courses—Orbital Mechanics
Newton was the first to realize that objects could, in theory, be sent into orbit around Earth. Explore how this works in practice, using the ideas of energy and angular momentum to study how satellites, moons, planets, and stars move through space.
The Falling Laboratory
Einstein focused on gravity in his general theory of relativity. Hear about his "happiest thought"--the realization that a man in free fall perceives gravity as zero. This simple insight resolved a mystery going all the way back to Newton and led Einstein to the startling discovery that gravity affects light…
Escape Velocity, Energy, and Rotation
Begin the first of several episodes that dig deeper into Newton's laws than Newton himself was able to go. In this episode, apply the key concepts of energy and angular momentum to study how gravity affects motion. As an example, use simple algebra to calculate the escape velocity from Earth.
The Strangest Force
Begin your exploration of gravity with Isaac Newton and the famous story of the apple. Why was it such a breakthrough to connect a falling apple with the faraway moon? Review the essential characteristics of gravity and learn why small asteroids and large planets have such different shapes.
Universal Gravitation
See how Newton was able to finish Kepler's revolution by formulating the law of universal gravitation, which says that every object exerts an attractive force on every other object. Also explore Newton's related discovery of the three laws of motion, which underlie the science of mechanics.
Revolution in the Heavens
Drawing on ideas and observations of Nicolaus Copernicus and Tycho Brahe, Johannes Kepler achieved a great insight about gravity by discovering three laws of planetary motion, relating to the mathematics of orbits. The cause of planetary motion, he determined, must lie in the sun.
Lava Worlds
Explore the theoretical limit of the smallest possible orbit for a planet, taking into consideration tidal stresses and other destructive processes. Then focus on Professor Winn's search for such objects, which found probable lava worlds--planets heated to rock-melting temperatures by their extreme closeness to their host stars.
Part of the Series: The Planets
A massive red sun dominates the sky above a parched barren landscape.You could be forgiven for thinking we were on Mercury, but this is planet Earth three billion years from now. As the Sun grows to the size of a Red Giant star, its warming breath penetrates further through its…
Next Stop for the Aviation Industry - Space!
Part of the Series: The Amazing World of Aviation
In 1982 the US government initiated a top secret research program known as Copper Canyon, to investigate the possibility of a single stage-to-orbit airplane which could take off and land horizontally. In 1990 the X-30 National Aero-Space Plane was developed by MacDonald Douglas, Rockwell International and General Dynamics in an…