What's the Sun Made Of?

Not every basic astronomy question is easy to answer, not even ones about the most important object in the sky, our sun.

In a deep feature, Alex Witze explores a controversy that's bubbled up among the people who study the sun, aka the heliophysics community. It turns out that scientists aren't exactly sure what the sun's made of. In the 1980s, people made some guesses that have been presumed to be accurate until recently. Now, new simulations of the sun's behavior indicate that there might be substantially less of the heavier elements like oxygen than we thought.

Why does that matter? Astronomers often use the sun, the easiest-to-study star, as a kind of standard measure for other astronomical objects. Change the facts about the sun, and it's like changing the length of an inch.

"And because the sun is the yardstick by which many other astronomical phenomena are measured, if scientists change their ideas about solar chemistry, they must also modify their thoughts about the chemical composition of sunlike stars," Witze writes. "Those changes, in turn, affect ideas about how galaxies evolve, such as the rate at which stars form over time, synthesizing and ejecting heavier elements out into the universe."

There's another reason to check out Witze's story, too. The latter half delves into how the scientific sausage is made. At a time when contentious debates in politically charged topics like climate science threaten to warp the perception of science, it's important to remember that most scientists don't work in high-profile fields. And researchers like these, who are outside the mainstream media spotlight, can serve as a standard measure for normal behavior in scientific discourse.

Image: A coronal hole on the sun. SDO/NASA.