Historic aurora-causing sunspot returns – Newsweek

The massive sunspot that caused spectacular auroras around the world earlier this month is about to look towards Earth again.

This sunspot, AR3664, was about 15 times wider than Earth when it fired a series of coronal mass ejections on May 10. These collided with our planet’s magnetic field, making the Northern Lights visible in all 50 US states and beyond. the most powerful geomagnetic storm in decades.

This sunspot rotated away from Earth as the Sun slowly rotated, but now it’s about to reappear, putting our planet in the line of fire once again.

‘This activity was associated with a huge sunspot, which is now orbiting the far side of the Sun and which takes about a month to rotate. A sunspot group of this size usually lasts a long time, so should be visible again in a few weeks. reach a central ‘dangerous’ position within about three weeks (it will then take two to three days for the effects to reach us),” said Martin Connors, professor of space science and physics at Canada’s Athabasca University. Newsweek just after the storms of May 10.

Sunspots are areas on the Sun’s surface with reduced surface temperature, caused by concentrations of magnetic field activity, appearing as spots that are darker than surrounding areas. This increased magnetic activity means that sunspots are prone to bursts of radiation (solar flares) and ejecting huge plumes of solar plasma, known as coronal mass ejections (CMEs).

When the charged particles from a CME reach Earth, they interact with the planet’s magnetosphere, the protective magnetic bubble surrounding it, creating a geomagnetic storm. Depending on their strength, these geomagnetic storms are ranked on a scale from G1 (small) to G5 (extreme).

The May 10 storm, caused by a train of CMEs hitting Earth, was the first G5 geomagnetic storm seen since 2003 and is considered one of the most powerful storms our planet has experienced in recent centuries.

“G5 storms occur about once a decade. They are unusual because they represent the strongest category of geomagnetic storms, occurring much less frequently than weaker events,” Jim Wild, professor of space physics at Lancaster University, told IPS. Newsweek.

The solar particles collide with the gas in our atmosphere during a geomagnetic storm, causing them to glow in the stunning colors seen during the aurorae. Different gases emit different colors: oxygen produces green and red light, while nitrogen emits blue and purple light.

As AR3664 spins back toward our planet, we may once again be at risk of powerful solar flares and CMEs heading our way.

The sunspot is clearly still very active. Just yesterday, a class X2.8 solar flare was seen erupting, causing a radio blackout over East Asia and accompanied by a CME that missed Earth. It should be fully pointed towards Earth by the end of the week and could lead to unusually widespread northern lights.

“I would say mark your calendars to be on the lookout for auroras starting in about three weeks,” Connors said three weeks ago.

Do you have a tip about a scientific story that Newsweek should cover? Do you have a question about sunspots? Let us know at science@newsweek.com.