Cosmic Tigerwoods
Beneath that blazing facade
Scientists are still trying to pin down the abundances of elements that swirl and churn beneath the sun's busy surface.
IN the pantheon of cosmic celebrities, the sun is one true superstar. It's not only the Earth's prime source of light and heat it also fuels the greenery that makes breathing possible, keeps time by setting the body's daily rhythms and spits out charged particles that create the beauty of the aurora borealis. But for all its roles on life's stage, the sun remains something of an inscrutable star. You might say it's the Tiger Woods of the cosmos. Behind its blazing facade, the sun turns out to be reluctant to give up its secrets. Most frustratingly, astronomers haven't figured out one of the most basic facts about Earth's nearest star: exactly what it's made of. "We really don't know what the sun's composition is," says Carlos Allende Prieto, an astronomer at the Instituto de Astrofisica de Canarias in the Canary Islands. "It's a big problem." Physicists do know a lot about the sun and how it works: Hydrogen atoms fuse in its core, forging helium and heavier elements and spewing out energy in the process. But over the past several years, scientists have dramatically overhauled estimates of the sun's chemical makeup. In particular, they say there may be far less of key elements such as oxygen, carbon and nitrogen than previously thought. These changes are major enough to throw into question other basic assumptions about the sun, such as ideas about how sound waves travel through its interior, ringing it like a gong. 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. 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. "People always compare stars of the same type to the sun, and now the sun has changed," says astronomer Nicolas Grevesse of the University of Liège in Belgium. "Now we're rechecking everything, restarting all the analyses from A to Z." Slowly, however, researchers are edging toward an answer. New, more sophisticated computer models have improved understanding of the sun's atmosphere, permitting better estimates of chemical abundances. Deeper discussions of which data to include, and which to leave out, are helping smooth battle lines between research teams arguing over what the final numbers should be. Soon, stories about what Earth's superstar is made of could read more like trusted newspaper copy than celebrity gossip.
For all latest news, follow The Daily Star's Google News channel.
Comments