Curator Hal Wallace talks about the development of the laser, an invention that has as many practical uses as portrayals in science fiction and fantasy.

Curator Steven turner discusses the work and shop of Henry Fitz, America's first commercially successful telescope manufacturer.

ʺSolution of the Black-drop Mysteryʺ Jay M. Pasachoff, Director of Hopkins Observatory and Field Memorial Professor of Astronomy, Williams College.

ʺPublic Reaction to the Transit of Venus, 1882ʺ David DeVorkin, Curator of History of Astronomy, National Air and Space Museum, Smithsonian Institution, Washington, DC

ʺThe American Expeditions of 1874 and 1882ʺ Steven J. Dick, NASA Chief Historian, National Aeronautics and Space Administration, Washington, DC

“Endeavour's Wake: Captain Cook and the Transit of Venus” Richard Fisher, Director, Sun-Earth Connection Division, NASA Office of Space Science, Washington, DC“Endeavour's Wake: Captain Cook and the Transit of Venus”

The First Observation of a Transit of Venus” - Wilbur Applebaum, Professor Emeritus, Humanities Dept., Illinois Institute of Technology, Chicago, IL

Researchers have been traveling for decades to some of the coldest places on the planet to uncover some of the secrets from space that have been left behind on Earth.

Principal scientist of NASA's Mars Exploration Rover (MER) mission, launched in 2003 -- Dr. Steven Squyres speaks at the National Portrait Gallery about his pioneering role in launching unmanned missions to Mars. A portrait of Squyres by Susan Gamble and Michael Wenyon was on view in NPG's "Americans Now" exhibition, through September 25, 2011. Recorded at NPG, October 15, 2010.

Peoples all over the world have unique creation stories: how the universe, the world, people, and animals came into existence. This creation story comes from the Blackfeet of North America. It is currently on view in the Our Peoples gallery at the National Museum of the American Indian in Washington, DC.

NASA's Chandra X-ray Observatory, in orbit since 1999, studies the high-energy Universe, where black holes, exploding stars, and mysterious matter hold sway.

These three traditional Native American stories fancifully portray the origin of several features in the night sky. These stories come from the Paiute, Arikara, and Chippewa peoples. Six additional stories are currently on view in the Our Universes gallery at the National Museum of the American Indian in Washington, DC.

Portraits of astronauts John Glenn, Bob Crippin and John Young, by Henry Casselli -- the artist discusses his work. Image: John Glenn / Henry C. Casselli, Jr. / Graphite and watercolor on paper, 1998 / National Portrait Gallery, Smithsonian Institution; Gift of Taylor Energy Company LLC

The music of the “Five Directions” comes from the fundamental philosophy of East Asia, which describes the basic forces behind the formation of the universe and all physical phenomena. These consist of the cosmic dual forces, yin/yang, and the five physical elements (ohyeng): metal, wood, water, fire, and earth. The universe is sustained by the absolute balance and delicate order of yin/yang and ohyeng, which is reflected in the five spatial and dimensional directions (obang): east, west,...

Apollo 15 mission Astronaut Dave R. Scott cancels two die proofs of the 8c 1971 postage stamps commemorating a decade of US achievements in space. The stamps were issued the same day on Earth with a first-day ceremony at Florida’s Kennedy Space Center. The initial view shows Scott beside the Modularised Equipment Stowage Assembly with a mountain in the background behind the lunar module. As he narrates the procedure he's performing, the camera zooms in affording a view of the envelope. Scott...