Last night, a coronal mass ejection (CME) hit the Earth. At first, it seemed weak and did not cause an immediate magnetic storm. But as the famous fable “The Hare and the Tortoise” says, in this case, slow and persistent really does win. The stubborn Solar wind finally sparked an auroral substorm and created a dazzling northern lights spectacle down to the middle latitudes.
But how?
“Sometimes the slow and steady wins the race! Despite very low solar wind speeds, persistent -Bz for more than 8 hours allowed auroras to form and appear faint into the mid-latitudes,” wrote space weather forecaster and meteorologist Sara Housseal in a Post on X.
CMEs are ejections of plasma and magnetic fields from the sunThey carry electrically charged Atoms known as ions. When CMEs collide with the Earth’s magnetosphere, they can cause geomagnetic storms. During such storms, the ions interact with gases in Earth’s atmospherewhich emit energy as light. This light spectacle is called the Northern Lights or Aurora Borealis in the Northern Hemisphere and the Southern Lights or Aurora Australians in the Southern Hemisphere.
Although the CME Although it initially failed to trigger a geomagnetic storm, its persistence and optimal conditions in the interplanetary magnetic field (IMF) were the perfect ingredients for an auroral substorm.
Related: Where and when can you see the Northern Lights in 2024?
When the solar wind hits the Earth’s magnetosphere, it compresses the magnetosphere on the side of the Earth facing the sun and creates a magnetopause – the boundary where the solar wind Earth’s magnetic field, According to the European Space Agency (ESA). This causes most of the incoming particles to flow around the Earth, pulling the magnetosphere outward in a long tail on the night side of the planet.
When the IMF is facing south, it allows the CME to successfully connect with the Earth’s magnetic field, effectively funneling solar wind particles into the magnetosphere. This causes the magnetotail to expand and contract, which is called magnetic reconnection. During this reconnection event, energy is released. This pushes the particles back towards Earth, which then triggers an auroral substorm.
During auroral substorms, auroras can come to life with sudden brightening and rapid movement.
The following YouTube video from NASA illustrates this magnetic reconnection event that leads to auroral substorms:
Space weather physicist Tamitha Skov summed up the substorm process well in a Post on XSkov describes it as if the solar storm is charging the Earth’s magnetic field, like pulling back the rubber band of a slingshot. A substorm is created when the band springs back.
The “persistent CME effects” triggered moderate G2 geomagnetic storms at 10:59 p.m. EDT (2:59 a.m. GMT). according to the National Oceanic and Atmospheric Administration (NOAA) Space Weather Prediction Center.
Aurora hunters from all over the world had their eyes firmly fixed on the sky and were rewarded with some dynamic and colorful spectacles.
Self-confessed aurora hunter Monika Focht took these stunning images between 12:30pm and 2:30am local time (BST) from her garden in Sutherland, Scotland.
“I have been out in my yard many, many times, watching the statistics and using aurora apps,” Focht told Space.com in an email.
Focht’s persistence paid off when a brilliant northern lights spectacle began to dance in the sky.
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“The colors of the aurora are so special and magical that I also create a lot of works of art around the aurora,” Focht continued.
Lisa Pattenden also captured the impressive dancing Northern Lights over Scotland.
“Taken an hour ago, #Aurora in #Scotland. The bright moon made it a bit difficult but there it is,” Pattenden said. wrote in a post on X.
Taken an hour ago, #Aurora in #Scotland. The bright moon made it a bit tricky but there it is. @chunder10 @TamithaSkov @aurora_chasers @BBCScotWeather @bbcweather pic.twitter.com/vr5aPyQjCn27 August 2024
In the early morning hours, the Northern Lights were even visible over the Jungfrau in Switzerland; Jure Atanackov filmed the sight.
“Beautiful purple columns 10-15° high in the northern sky, seen from Jungfrau, Switzerland (46.5°N) this morning at 1:20 UTC. Further diffuse glow seen at 3:00 UTC,” Atanackov wrote in a post on X.
#Aurora: beautiful purple columns 10-15° high in the northern sky, seen from Jungfrau, Switzerland (46.5°N) this morning at 1:20 UTC. More diffuse glow seen at 3:00 UTC. @TamithaSkov pic.twitter.com/hv7lX6W1xr28 August 2024
In Canada, aurora hunter Justin Anderson captured this striking image of bright, dancing aurora borealis over Manitoba, Canada.
“BOOM! Aurora exploded over Manitoba tonight! It’s always funny when it goes through the Milky Way!” Anderson wrote in a Post on X.
BOOM! Aurora exploded over Manitoba tonight! Always fun when she dances through the Milky Way! 📍 Forrest, Manitoba@Vincent_Ledvina @TamithaSkov @TweetAurora pic.twitter.com/p7as6SuiYZ28 August 2024
In the meantime, STEVE also had an appearance.
STEVE – Strong Thermal Emission Velocity Enhancement – is an aurora-like glow that often accompanies the Northern Lights, but is nevertheless a phenomenon in its own right, according to the American Geophysical Union.
Benjamin Jurkovich photographed STEVE over Lake Stevens, Washington, USA
“STEVE! This is the longest-living specimen I have ever seen. Taken in Lake Stevens, Washington,” said Jurkovich wrote in a post on X.
STEVE! This is the longest one I’ve ever seen. Taken in Lake Stevens, Washington. #NorthernLights #Aurora @TamithaSkov pic.twitter.com/yP5uM59cUg28 August 2024
