Two powerful solar storm clouds are heading straight for Earth, triggering an aurora alert across northern Europe, Asia, Canada, and the northern United States.
Two giant flares—the second of which was an X-class, the most powerful of solar blasts—erupted on the sun’s fiery surface on September 9 and 10, shooting two outbursts of charged particles known as coronal mass ejections (CMEs) into space. Space weather officials predict that these plasma clouds will produce strong geomagnetic storms and hit Earth on September 12 and 13.
The flares themselves were observed by NASA, which posted stunning photos and videos of the events on its website.
Solar flares are powerful bursts of radiation that erupt from regions of the solar surface many times the size of our planet. They can cause disturbances in Earth’s atmosphere while disrupting GPS and radio signals. The disruptions can last as long as the flares do, anywhere from minutes to hours.
That is exactly what happened on Wednesday afternoon when the second, stronger, of the two flares occurred, producing a short blackout period in high-frequency communications that lasted for a few hours.
Since the radiation from the flares travels at the speed of light, 11.2 million miles (18 million kilometers) per minute, and the sun is about 93 million miles (150 million kilometers) distant, the radiation hits Earth within 8.5 minutes of the solar explosion occurring.
Ham radio operators who happened to be located on the sun-facing side of Earth at the time of the event on Wednesday actually detected the loud solar explosion, reporting a blast of radio noise on their shortwave receivers.
“It was absolutely howling,” Thomas Ashcraft, an amateur radio observatory owner in New Mexico, told spaceweather.com.
“By the time the flare peaked, it became almost too intense for my ears.”
Now attention has turned to the two CMEs that have Earth in their crosshairs. NOAA space weather forecasters report that when CMEs slam into Earth’s magnetic field, the results may include induced electrical currents that could trigger residential and commercial alarm systems, intermittent satellite navigation (GPS) problems, high-frequency radio outages, and potentially, northern lights.
So, the big question is whether we will get to see any sky fireworks from this solar storm. That will depend on the strength of the storm and the orientation of Earth’s dynamic magnetic field when it hits. Sky-watchers, particularly those in northern-latitude regions, should be on the lookout for possible auroras visible in the northern skies. Forecasters say that these sky glows may extend as far south as Pennsylvania, Iowa, and Oregon. (See “Pictures: Auroras of February and March.”)
The best time to try and capture pictures of auroras, in general, is between midnight and the pre-dawn hours. Face the northern sky and look for green or red glows that start near the horizon. In terms of equipment and technique, all you need to have is a tripod-mounted DSLR camera with a wide-angle lens, capable of taking exposures of up to 20 seconds with a remote timer. (Related: “Did You Hear the Northern Lights?”)
It’s important to remember that we are still in the very early stages of being able to predict when auroral displays will happen, and their potential intensity. But with some patience and luck we might be in for a decent cosmic light show this week.