by Solar flares, powerful bursts of radiation from the sun, are often preceded by a pre-flare spark, scientists have discovered. The finding could lead to better predictions of solar storms, which can disrupt power grids and communication systems on Earth.
The scientists made the discovery after delving into years of data from NASA’s Solar Dynamics Observatory (SDO), a satellite that has been observing the sun since 2010. Since the 1970s and 1980s, researchers have witnessed these flashes leading up to the flares, using tools like ground-based observatories, so there was a lot of anecdotal evidence that the flashes and flares were related, KD Leka (opens in a new tab), a senior research scientist at NorthWest Research Associates (NWRA) in Boulder, Colorado, told Live Science. But those researchers didn’t have instruments like SDO, which constantly observes and records the sun’s activity from space.
“Images of [the sun] they have definitely been helping scientists and forecasters understand when an active region is likely to produce flares,” Leka said.
In a new series of articles published in The Astrophysical Journal (opens in a new tab), Leka and his team analyzed nearly a decade of SDO data, zooming in on active regions of the sun known as sunspots. These dark areas are places where the sun’s magnetic field is particularly active due to the contortions deeper within the star. The contortions cause the sun’s magnetic field to twist and become tangled. And when those magnetic field lines return to their original shape, a huge burst of energy erupts from the surface.
These explosions can manifest as a sun flare or a coronal mass ejection (CME). Solar flares are intense waves of X-rays and energy that shine in all directions. Electromagnetic energy moves at the speed of light and can reach Earth in 8 minutes. CMEs, by contrast, are explosions of highly charged particles that burst in a particular direction. They move more slowly, from 155 to 1,900 miles per second (250 to 3,000 kilometers per second); a CME can take several days to sweep the Earth.
Both types of explosions can cause damage to power and telecommunications systems on Earth, but are generally harmless to humans and other living things.
In thousands of terabytes of SDO data, Leka and his team found that solar flares are often associated with a moment of brightness, like when you strike a match and it lights up before it lights up. These sparks occurred up to a day before flares erupted from the same region of the sun, the authors found.
The findings, while exciting for our understanding of solar physics, do not mean that scientists can now predict solar flares, Leka said. Think of it like forecasting a volcanic eruption: Earthquakes near an active volcano tell scientists that underground magma is shifting and could be causing an eruption. So scientists monitor earthquakes and modify models to predict when an eruption might occur. But no single earthquake is a predictor of a volcanic eruption.
“Later, combining all this information from the surface to the corona [the sun’s outer atmosphere] should allow forecasters to make better predictions about when and where solar flares will occur,” the study co-author said. Karin Dissauer (opens in a new tab)NWRA Research Scientist, said in a statement (opens in a new tab).
For now, the research has raised new questions for Leka, such as how the dynamics of the sun’s magnetic field is connected to processes occurring deep within the sun, and how to combine data from both regions to help scientists figure out predict solar flares.
