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GIOVANNI DOMENICO CASSINI
GIOVANNI DOMENICO CASSINI
Genoa, Italy (1625 - 1712)
Giovanni Domenico Cassini was an Italian mathematician, astronomer, engineer, and astrologer. Cassini was an astronomer at the Panzano Observatory, from 1648 to 1669, professor of astronomy at the University of Bologna and became, in 1671, director of the Paris Observatory. Along with Robert Hooke, Cassini is given credit for the discovery of the Great Red Spot on Jupiter (ca. 1665). Cassini was the first to observe four of Saturn's moons, which he called Sidera Lodoicea. Around 1690, Cassini was the first to observe differential rotation within Jupiter's atmosphere.
 

Enjoy these insightful and educational video clips drawn from over 70 hours of interviews with the world's leading figures in astronomy, shot during the filming of 400 Years of the Telescope.

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Taft E. Armandroff

Adaptive vs. active optics at Keck
Taft E. Armandroff - W. M. Keck Observatory

Active optics compensate for slowly varying influences on the telescope optical system, so the mirrors and the mechanical systems that hold the mirrors into place. So these change rather slowly over the course of the night with the direction of telescopes pointed or with temperature.

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Taft E. Armandroff

Keck telescopes overview
Taft E. Armandroff - W. M. Keck Observatory

The Keck telescopes are the two largest fully stirrable optical infrared telescopes in the world. They were the first of the new generation of large telescopes.

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Taft E. Armandroff

Astronomy answers at Keck
Taft E. Armandroff - W. M. Keck Observatory

How do stars form and evolve? How does the galaxy form and evolve nearby galaxies? What are the real influences? What makes one galaxy a spiral and another an elliptical? What makes one star live a hundred thousand years and another live sixteen billion years?

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Taft E. Armandroff

Segmented mirror technology
Taft E. Armandroff - W. M. Keck Observatory

Jerry Nelson developed a revolutionary technique for instead of having one mirror as all telescopes had before Keck and following the prescription of say, the classic telescopes like the Palomar 200 inch, the Mt. Wilson 100 inch, and the Kitt Peak and Cerra Tololo four meters to make it much more achievable in terms of issues like weight, in terms of cost to break the mirror into segments.

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Taft E. Armandroff

The 30-meter telescope
Taft E. Armandroff - W. M. Keck Observatory

The 30-meter telescope plans to use segmented mirror technology just like Keck, and between Keck and 30 meter telescope we have a great interchange of technical knowledge on topics like controls systems, for keeping the mirrors precisely positioned, working on illuminizing the segments and adaptive optic systems.

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