We are all seeing rather less of the Sun. Scientists looking at five decades of sunlight measurements have reached the disturbing conclusion that the amount of solar energy reaching the Earth's surface has been gradually falling. Paradoxically, the decline in sunlight may mean that global warming is a far greater threat to society than previously thought.
The enduring luster of gold, the conductivity of copper, the strength of steel—the special properties of metals have reshaped societies and defined eras; they have such an important role in human history that entire ages have been named after them. But what gives metals their astounding characteristics? From the perfect ring of a bronze bell to the awe-striking steel construction of Beijing’s “Bird’s Nest” stadium, how have humans perfected metalworking? And how have metals enabled our modern hi-tech world? Explore the science of metals with chemists and engineers as they literally test the mettle of metals and investigate how these remarkable materials have ushered humanity from the Stone Age to the stars.
Between the blue sky above and the infinite blackness beyond lies a frontier that scientists have only just begun to investigate. In "At the Edge of Space," NOVA takes viewers on a spectacular exploration of the Earth-space boundary that's home to some of nature's most puzzling and alluring phenomena: the shimmering aurora, streaking meteors, and fleeting flashes that shoot upwards from thunderclouds, known as sprites.