December 30, 2024
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Auroras can light up the New Year’s sky after solar flares
Will 2024, a year marked by celestial displays, be lit by yet more auroras?
The northern lights seen above Lindisfarne Castle in England on October 10, 2024.
Owen Humphreys/PA Images via Getty Images
The sun is saying goodbye to 2024 with a bang—or rather, several bangs. Our star produced three powerful flares on December 29. Also, it may have sent bubbles of material speeding through space. paint Earth’s skies with auroras as many earthlings mark the turn of the year.
Solar flares They are classified by their peak brightness at X-ray wavelengths, with Class X flares being the brightest. Our star’s Dec. 29 activity included three such flares, at 2:18 a.m., 11:14 p.m. and 11:31 p.m. EST, according to a NASA statement. The bursts represent a constant flurry between what scientists have identified as the maximum of the sun’s current activity cycle, which also produced stunning auroras as far south as Florida in May and October.
It dictates the 11-year activity cycle of the sun magnetic fields that roam the surface of our star. “Our sun is a giant magnet, so most things that happen on the sun are driven by magnetism,” says Maria Kazachenko, a heliophysicist at the University of Colorado Boulder and the National Solar Observatory.
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Scientists measure the sun’s activity by counting the dark spots that mar its surface. Each sunspot has a smaller magnetic field, even though the sunspots themselves are the size of Earth. Sudden changes in the configuration of the sunspot’s magnetic field, called magnetic reconnection, can release large amounts of energy, causing a solar flare. But scientists are still trying to understand what events can cause magnetic reconnection.
“The main problem with these creatures is that we can’t stick a thermometer or a magnetometer inside the solar flare,” says Kazachenko. “So it’s very difficult to understand what’s going on.”
And magnetic reconnection in one sunspot can trigger a phenomenon in another sunspot—even at a great distance—in what scientists call a benign eruption. “We often see flares occurring in groups,” says Kazachenko. The two flares that occurred on Sunday evening represented such a group: spots on opposite sides of the sun’s equator that exploded less than 20 minutes apart.
But flares are just bursts of radiation. Normally, for an aurora to occur, the sun must release a bubble of plasma, which scientists call a coronal mass ejection (CME), a phenomenon that follows some but not all flares. Whether or not a CME occurs depends on the details of the magnetism. In some flares, magnetic fields trap material inside the sun. At other times, they allow large bursts of plasma to escape the turbulent star. And the more material there is, the better the chances of more spectacular auroras, Kazachenko says.
In the case of Sunday’s activity, three large flares produced CMEs. Whether they will create Aurora or not is still unclear. But the National Oceanic and Atmospheric Administration’s Weather Prediction Center has issued a geomagnetic storm watch for an event that occurred on Dec. 31 and Jan. 1.
Forecast uncertainty arises from a number of factors. Only two CMEs are on track to potentially hit Earth, and those could still cause shocks, making predictions about aftereffects difficult. In addition, Kazachenko says, for an aurora to form, the plasma ball’s magnetic field must align with the Earth’s magnetic field. Otherwise, the plasma will simply flow through, barely disturbing our planet.
The latest activity comes as no surprise to scientists who have been carefully monitoring the sun’s progression through its activity cycle. At a press conference in October, experts announced that the sun is officially at its maximum in that cycle and will remain so for much of 2025.
“We expect the maximum phase to be on the longer side, roughly three to four years long,” said Lisa Upton, a solar scientist at the Southwest Research Institute, during the conference. “We’re currently about two years into the maximum period, so we anticipate another year or so before the maximum phase actually enters the decline phase.”
Throughout the rest of the solar maximum and beyond, scientists expect more activity and more impacts on Earth. “We anticipate additional solar and geomagnetic storms will lead to opportunities for aurora sightings in the coming months,” NASA scientist Kelly Korreck said at the same press conference.
And while solar flares can wreak havoc on orbiting satellites and astronauts, as well as Earth’s power grid, scientists are happy to see the 2024 activity and this solar cycle, which has coincided with the arrival of a coincidental one. A massive new solar telescope and two separate spaceshipsall designed to unravel the mysteries of how the sun works.
“This year has been amazing,” says Kazachenko. “Now we’re experiencing that solar maximum, and now we have this great set of instruments that observe the sun in a new way. We are now living in the golden age of solar multi-messenger astronomy”.
