STORMS FROM THE SUN
THE NATURE OF SPACE WEATHER HASN’T CHANGED MUCH. BUT SOCIETY HAS, AND UNDERSTANDING AND PREDICTING THE PHENOMENON IS MORE IMPORTANT THAN EVER.
Space weather is not something that most of us typically think about on a daily basis. But the Sun’s charged particles and magnetic field are constantly sweeping through space and colliding with the Earth’s own magnetic field. Occasionally, the auroras fill the sky with light dancing along these field lines. The most extreme space weather, however, happens when the Sun blasts billions of tons of energized particles directly towards the Earth at speeds up to 1,800 miles per second.
These explosions, known as coronal mass ejections (CMEs), lift off from the Sun’s outer atmosphere — the corona — and can cause intense geomagnetic storms and negatively affect astronauts, satellites, and spacecraft.
SPACE ODDITIES
Geomagnetic storms happen when the Earth’s magnetic field is disturbed. The most extreme geomagnetic storms are driven by CMEs, which can actually energize the Earth’s magnetic field, says James Spann, a space weather lead at NASA. “The impact of a CME on a magnetized body like the Earth can be very catastrophic depending on its size and speed.”
One of the most intense CMEs, known as the Carrington Event, is believed to have taken place on Sept. 1, 1859, reaching Earth 17.5 hours later and setting off a large geomagnetic storm. Auroras, more commonly a northern phenomenon, were seen as far south as the Caribbean and telegraph lines caught fire as communications were disrupted across the world.
More recently, changes in magnetic fields during geomagnetic storms induce currents along power lines that can damage transformers and cause power outages. The most serious event happened on March 13, 1989, and left 6 million people without power in Québec, Canada, for nine hours.
The potential impact on society is far greater today due to the vast extent to which we depend on technology, says Howard Singer, chief scientist at the NOAA Space Weather Prediction Center. “The number of technological systems that can be affected by space weather just keeps growing.”
CMEs can also pose a risk to satellites and spacecraft as charges build up on the surface and inside electronics. But space weather forecasters that monitor the sun for CMEs can help reduce astronaut exposure to the radiation that solar storms can cause. “When we are thinking of human exploration of space, we want to know what we are getting into,” says Alexa Halford, a space physics researcher at NASA. “Just like if you were packing for a vacation somewhere.”
“The number of systems that can be affected by space weather just keeps growing.”