[SFDXA] THE BASTILLE DAY EVENT, 25 YEARS LATER:

[Bill]

*Space Weather News for July 14, 2025*
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*THE BASTILLE DAY EVENT, 25 YEARS LATER: *You know a solar flare is 
strong when even the Voyager spacecraft feel it. Twenty-five years ago 
today, on July 14, 2000, the sun unleashed one of the most powerful 
solar storms of the Space Age—an event so intense, its shockwaves 
rippled all the way to the edge of the solar system.

<https://spaceweather.com/images2025/14jul25/vgr_anim.gif>

Voyager 2 felt the explosion 
<https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2002GL014729> 
180 days later; Voyager 1, 245 days. The debris was still coherent and 
traveling faster than 600 km/s (1.9 million mph) when it slammed into 
the two spacecraft—then more than 9 billion kilometers from the sun.

Here on Earth, the effects were almost immediate. Within minutes, 
extreme ultraviolet and X-ray radiation bathed our planet and its 
satellites. Ground-based sensors registered a rare GLE (ground-level 
event) as energetic particles cascaded through the atmosphere.

"People flying in commercial jets at high latitudes would have received 
double their usual radiation dose," recalled Clive Dyer of the 
University of Surrey Space Centre. “It was quite an energetic event—one 
of the strongest of its time."

Because the flare happened on July 14th, it's called "The Bastille Day 
Event" after France’s national holiday. However, auroras did not appear 
until the following day, July 15th, when a coronal mass ejection (CME) 
arrived. The 1500 km/s impact triggered an extreme geomagnetic storm (Kp=9).

<https://spaceweathergallery2.com/indiv_upload.php?upload_id=186775>
Auroras on July 15, 2000, photographed by (left) Ronnie Sherrill in 
North Carolina and (right) NASA's IMAGE spacecraft.

In New York, Lou Michael Moure remembers his sky catching fire: "I was 
living on Long Island. A family member ran into my room, shouting about 
'the sky on fire.' Sure enough, the sky blazed white, green, then red 
from horizon to horizon." In North Carolina, Uwe Heine was doing 
yardwork when bright red auroras appeared straight overhead: "I told our 
neighbor those weren’t sunset colors. It was an aurora—and super rare 
this far south!"

By the time the storm ended on July 16th, auroras had been sighted as 
far south as Texas, Florida, and even Mexico.

The Bastille Day Event was important because, for the first time in 
history, spacecraft throughout the solar system were equipped with 
instruments capable of studying such a storm. Most notably, it was the 
first major solar storm observed by SOHO, the Solar and Heliospheric 
Observatory, which gave researchers an unprecedented look at how extreme 
flares unfold and evolve.

	
Above: SOHO images of the X5.7-class Bastille Day solar flare (left) and 
CME (right). "Snow" in the images is a result of energetic protons 
hitting the spacecraft

Later studies <https://www.sumseq.com/files/Paper12_BAST.pdf> described 
how an X5.7-class flare, erupting near the center of the solar disk, 
released 10³³ ergs of magnetic energy—equivalent to a thousand billion 
WWII-era atomic bombs. The resulting CME generated a massive barrier of 
magnetic field and plasma, which swept away galactic cosmic rays as it 
raced through the heliosphere. Even the Voyagers felt this unusual dip 
in cosmic radiation, known as a Forbush Decrease.

Could it happen again? It could happen again /this week/. We’re 
currently near the peak of Solar Cycle 25, and another X-flare is well 
within the realm of possibility.

Happy Bastille Day.

https://spaceweather.com/

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