Planetary Radio • Apr 19, 2017

McDonald Observatory and the Quest for Dark Energy

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On This Episode

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Taft Armandroff

Director for McDonald Observatory

Marc Wetzel

Education Coordinator for McDonald Observatory

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Karl Gebhardt

Project Scientist for Hobby-Eberly Telescope Dark Energy Experiment (HETDEX)

Herman Kriel

Project Manager for Hobby-Eberly Telescope Dark Energy Experiment (HETDEX)

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Larry Ramsey

Professor of Astronomy for Penn State University

The University of Texas at Austin’s observatory is high in the hills of west Texas. In this special episode, Mat Kaplan joins the tens of thousands who visit it each year. The occasion was the dedication of the vastly upgraded Hobby-Eberly Telescope (HET), third largest on Earth. The great instrument may help us understand the mysterious force known as dark energy. Mat talks with the Observatory’s Director and others who are part of this effort. You’re also invited to a McDonald star party!

Fisheye View of the HET
Fisheye View of the HET Part of the great 10-meter mirror can be seen below the dome in this wide-angle view of the HET interior.Image: John Stoke
McDonald Director Taft Armandroff
McDonald Director Taft Armandroff Taft talks with reporters outside the HET.Image: Mat Kaplan
Reporters Tour the HET
Reporters Tour the HET Reporters, including Mat Kaplan (kneeling in blue shirt) listen to HETDEX Project Manager Herman Kriel describe the Hobby-Eberly Telescope.Image: John Stoke

This week's question:

Within 100 or so, how many CONFIRMED exoplanets have been discovered?

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, April 26th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

How many moons in our solar system are larger than Pluto?


The answer will be revealed next week.

Question from the week before:

Who first noted what turned out to be Neptune, even though he is not credited with the discovery because he didn’t report its movement and may have thought it was a star?


Galileo observed Neptune in the early 1600s, but thought it was a star. Or did he?