LOS ANGELES — Sunspots, those dark regions on the surface of the sun whose high magnetic activity has ripple effects for Earthlings, seem to emerge and fade without warning. But now, by listening to the sounds the sun makes, scientists have managed to predict when a sunspot will appear up to two days beforehand.
The findings, published in Friday's edition of the journal Science, could help solar physicists understand how to better predict solar flares and other space weather events that can harm astronauts and damage power and electronics systems on Earth.
The sun contains plasma, which is gas that has been superheated to the point that electrons are stripped from the nuclei of their atoms. The constant churning of that plasma on the solar surface generates sound waves, which travel toward the interior of the sun before they are bent back toward the surface. It usually takes an hour for sound waves to bounce from one point at the surface to the next, traveling roughly 60,000 to 125,000 miles in the process.
But a pocket of high magnetic activity deep within the sun, destined to rise to the surface and become a sunspot, is more buoyant than the churning plasma around it. So it floats toward the surface faster — and causes sound waves to move faster, too. The stronger the sunspot, the more buoyant it is and the faster it rises to the surface.
The findings could prove useful to scientists looking to tie sunspots to the space weather events generated days later. Because areas of high magnetic activity are closely linked to dangerous solar activity — from flares to violent coronal mass ejections — being able to understand that magnetic activity may help predict oncoming solar storms and allow people to prepare for them, rather like putting up storm windows after a hurricane warning.
For example, satellites could be switched into safe mode to protect the sensitive electronics inside.