No big deal, just a Nobel Prize winner, and the leader of space science in China this week on planetary radio.

Welcome, I'm Matt Kaplan, of the Planetary Society with more of the human adventure across our

solar system and beyond.

Does dark energy delight or disgust you? Either, the first person to thank or blame is Saul Perlmutter.

The Nobel Committee gave him half of the credit for its discovery.

We'll talk with Saul along with Wang Chi, Director General of China's National Space Science Center.

Then just for fun, we'll talk with Kevin Hussey, creator of NASA Eyes, the growing collection of apps that will take you along with

Cassini and Voyager are out to world circling other stars. Stay through

this week's What's Up with Bruce Betts for a lovely message that Carl Sagan created for future

Martians. It was 20 years ago today, more or less, that we first heard the expansion

of our universe is accelerating.

Two decades later, we still don't know why, but we do know it was predicted by Einstein's

general theory of relativity and then rejected by Albert himself as being too too crazy.

When the Nobel Prize for this discovery was awarded in 2011, half of the credit went to Saul Perlmeter of UC Berkeley.

Saul is a physicist, of course, but as you'll hear, he is an experimentalist

examining the real observable world to prove or disprove explanations theorists

come up with, and sometimes to reveal corners of existence that catch those theorists by surprise. The recent

biannual meeting of the International Committee on Space Research devoted

an entire track to this 20th anniversary and to a review of what we know and don't know about dark energy.

Not surprisingly, Professor Perlmutter was the lead speaker. Dr Perlmutter just came out of the presentation that you gave to open the

Co-Sations on dark energy. You seem to be having a delightful time talking

about how you helped to get us, led the effort to get us to where we are now which is I think

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