Scientists Bring The Sun Down To Earth To Learn How It Works

Dec 30, 2014
Originally published on February 5, 2015 1:13 am
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ROBERT SIEGEL, HOST:

In Albuquerque, scientists have been re-creating pieces of the sun right here on Earth. They've created these solar samples to resolve a mystery about the way the sun behaves. NPR science correspondent Joe Palca has been exploring the minds and motivations of scientists and inventors. It's a series called Joe's Big Idea. And he's back with this sunny installment.

JOE PALCA, BYLINE: Solar physicist James Bailey says about a decade ago, scientists were pretty secure in their knowledge about how the sun worked.

JAMES BAILEY: And what I mean by that is that theoretical predictions matched all of the available observations to a very high level of accuracy.

PALCA: In other words, the sun was behaving the way scientists thought it should behave.

BAILEY: So around the year 2000, everybody was happy; theories agreed with observations and things were good. Then some people came along and said wait a minute, our new analysis shows that there's about half as much oxygen in the sun as what we thought before.

PALCA: In fact, the new research suggests that the amounts of other elements such as nitrogen and carbon were wrong as well. Bailey says this was a big, big problem.

BAILEY: The theoretical models no longer matched the observations.

PALCA: Now there are basically two possibilities here - either the theoretical models were wrong or the various elements inside the sun were behaving in a way that scientists didn't understand. Bailey was of the opinion that the theories were right. There is other evidence supporting them so he decided to look into the other possibility. To do that, he and his colleagues used a unique device called the Z machine at the Sandia National Laboratory to re-create the heat and pressure inside the sun and see how the solar elements behaved.

BAILEY: It's not that unusual for people to create high temperatures and high densities. What's hard is to create high temperatures and high densities in a big enough sample that you can actually study what's going on.

PALCA: And how big was your sample, just for curiosity?

BAILEY: It's like a grain of sand.

PALCA: But that's big enough?

BAILEY: But that's big enough.

PALCA: The first solar element they studied was iron. And as they report in the current issue of the journal Nature, iron behaves differently than scientists predicted it would. And that may mean that oxygen, nitrogen and carbon may be behaving differently as well.

BAILEY: It's reasonable to be suspicious that, well, if iron is wrong, maybe some of the other elements might be wrong also.

PALCA: So scientists might be right about the amounts of various elements inside the sun; they just might not be right about how those elements are behaving. Bailey says his new measurements have implications for stars elsewhere in our galaxy. Astronomers have now found more than a thousand planets orbiting stars outside our solar system, and some might - possibly - harbor life.

BAILEY: One of the first things that you want to do when you discover a star system that's got some orbiting planets is you want to understand the characteristics of the star that the planets are orbiting around. But if you don't have the composition of the other stars correct, then mistakes will be made in inferring the properties of those other stars.

PALCA: Well, you'd hate to travel all that way and find you made a mistake.

BAILEY: (Laughter) Yeah. Well, of course, it'll be a while before we make that journey. But...

PALCA: Well, that's true. But even if we have to observe those stars from a distance, it would nice to understand which ones are worth scrutinizing when looking for life elsewhere in the universe. Joe Palca, NPR News. Transcript provided by NPR, Copyright NPR.