Planetary Radio • Aug 09, 2017

Dark Energy Attracts? Astrophysicists Jason Rhodes and Alina Kiessling

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On This Episode

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Jason Rhodes

Principal Scientist for Jet Propulsion Laboratory

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Alina Kiessling

Research Scientist for Jet Propulsion Laboratory

JPL astrophysicists Alina Kiessling and Jason Rhodes were brought together by their fascination over the mystery of dark energy. They talk with Planetary Radio about their research and the many missions they are contributing to, including WFIRST, a unique new space telescope. Director of Space Policy Casey Dreier reviews the US Senate’s 2018 NASA budget proposal. CEO Bill Nye says enjoy the Great American Eclipse, but be careful! All this and What’s Up with Bruce Betts.

Jason Rhodes and Alina Kiessling
Jason Rhodes and Alina Kiessling Image: Alina Kiessling
WFIRST Telescope
WFIRST Telescope Artist's concept of NASA's Wide-Field Infrared Survey Telescope (WFIRST).Image: NASA / GSFC / Conceptual Image Lab
Mixing galaxies
Mixing galaxies NGC 6340, captured in May/June 2014. View additional informationImage: Adam Block / Mount Lemmon SkyCenter / University of Arizona

This week's question:

When is the next total solar eclipse on Earth after the one on August 21, 2017?

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, August 16th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

Just before totality in a solar eclipse, the sun is blocked except for sunlight streaming through lunar valleys along the limb. Who are these brief, bright “beads” of light named after?


The answer will be revealed next week.

Question from the week before:

Mars’ orbit is elliptical, of course. How much closer is it to the sun when it is at perihelion (closest to the sun) than it is at aphelion (farthest from the sun)?


Mars is roughly 42.5 million kilometers closer to the sun at perihelion than at aphelion, or .285 AU, or about 354 billion Mars bars.