Bastille Day solar storm
Aurora as seen by IMAGE.PNG
IMAGE ultraviolet image of the Aurora Borealis on 15 July 2000
TypeGeomagnetic storm
Formed14 July 2000 (2000-07-14)
Dissipated16 July 2000 (2000-07-16)
DamageMinor satellite and terrestrial power transformer damage
Areas affectedWorldwide

The Bastille Day solar storm was a powerful solar storm on 14-16 July 2000 during the solar maximum of solar cycle 23. The storm began on the national day of France, Bastille Day. It involved a solar flare, a solar particle event, and a coronal mass ejection which caused a severe geomagnetic storm.[1][2]

Overview[edit]

Extreme ultraviolet Imaging Telescope (EIT), 195 Å
Large Angle and Spectrometric Coronagraph (LASCO)
In EIT footage, the X5.7-class solar flare appears as a bright flash near the center of the solar disk; in LASCO footage, the subsequent halo CME appears as an expanding, bright ring around the Sun (represented by the white circle). Much of the footage from both instruments is obscured by noise caused by high energy particles colliding with the instruments' sensors.[3][4]

Solar flare and particle event[edit]

On 14 July 2000 from about 10:03 to 10:43 UTC, GOES satellites detected a very strong, X5.7-class, solar flare[note 1] which peaked in soft X-ray intensity at around 10:24 UTC. This flare originated from the solar active region AR9077 which was located near the center of the Sun's disk (N22 W02) at the time of the flare.[5][6]

Starting at around 10:41 UTC, GOES satellites began detecting a strong, S3, solar particle event[note 2] associated with the ongoing X5.7-class flare.[1] This resulted in high energy protons penetrating and ionizing parts of the Earth's ionosphere and creating noise in various satellite imaging systems such as in the EIT and LASCO instruments.[3] Some of these particles had sufficient energy to generate effects measured on Earth's surface, an event referred to as a ground level enhancement. Although the flare was not extremely large, the associated solar particle event was the fourth largest since 1967.[6]

Geomagnetic storm[edit]

The detection of the solar flare was also followed by the detection of a halo, or Earth-directed, coronal mass ejection (CME) in coronagraph data starting at 10:54 UTC.[3] This CME reached Earth on 15 July causing a geomagnetic storm on 15-16 July which would reach a peak Kp index of 9+ in the late hours of 15 July corresponding to an extreme-level, or G5, geomagnetic storm[note 3] and register a peak Dst of −301 nT. The storm caused minor damage to power transformers and satellites.[9] It was also one of only two solar storms having registered a maximum Kp of 9+ since the March 1989 geomagnetic storm, the other being the 2003 Halloween solar storms.[10]

Aftermath[edit]

Due to being the first major solar storm since the launch of various solar-monitoring satellites, the Bastille Day event proved important towards helping scientists piece together a general theory of how eruptions on the sun occur as well as protecting the Earth from a larger event, such as a Carrington-class event, some day in the future.[11]

Despite their great distance from the Sun, the Bastille Day event was observed by Voyager 1 and Voyager 2.[12]

See also[edit]

Notes[edit]

  1. ^ The label X5.7-class implies that the solar flare had a peak soft X-ray flux of 5.7×10−3 W/m2 in the 0.1 to 0.8 nm (1 to 8 Å) passband. (See Solar flare § Soft X-ray classification.)
  2. ^ The label S3 is assigned to solar particle events which have a flux of protons with energies ≥10 MeV peaking between 103 and 104 proton flux units (or particle cm−2 s−1 sr−1).[7][8]
  3. ^ The label G5 is assigned to geomagnetic storms which reach a peak Kp index of 9 or more.[7] (See K-index § G-scale.)

References[edit]

  1. ^ a b "Space Radiation Storm". NASA. 2004-07-14. Archived from the original on 2000-08-15. Retrieved 2007-03-09.
  2. ^ "NASA Says Solar Flare Caused Radio Blackouts". The New York Times. Associated Press. 2000-07-14. Retrieved 2007-03-09.
  3. ^ a b c Andrews, M.D. (2001). "Lasco and eit Observations of the Bastille day 2000 Solar Storm". Solar Physics. 204: 179–196. doi:10.1023/A:1014215923912.
  4. ^ "SOHO Hotshots". soho.nascom.nasa.gov. Retrieved 4 November 2021.
  5. ^ Reiner, M.J.; Kaiser, M.L.; Karlický, M.; Jiřička, K.; Bougeret, J.-L. (2001). "Bastille Day Event: A Radio Perspective". Solar Physics. 204: 121–137. doi:10.1023/A:1014225323289.
  6. ^ a b Watari, Shinichi; Kunitake, Manabu; Watanabe, Takashi (January 2001). "The Bastille Day (14 July 2000) event in historical large sun-earth connection events". Solar Physics. 204: 425–438. Bibcode:2001SoPh..204..425W. doi:10.1023/A:1014273227639. S2CID 117394988. Retrieved 2 January 2021.
  7. ^ a b "NOAA Space Weather Scales | NOAA / NWS Space Weather Prediction Center". www.swpc.noaa.gov. Retrieved 7 August 2022.
  8. ^ "Solar Radiation Storm | NOAA / NWS Space Weather Prediction Center". www.swpc.noaa.gov. Retrieved 7 August 2022.
  9. ^ "Minor Damage Reported from Geomagnetic Storm" (PDF). Retrieved 2 January 2021.
  10. ^ "Top 50 Geomagnetic Storms". Retrieved 2 January 2021.
  11. ^ Moskowitz, Clara (14 July 2011). "Bastille Day Solar Storm: Anatomy of a Gargantuan Sun Tempest". Retrieved 2 January 2021.
  12. ^ Webber, W. R.; McDonald, F. B.; Lockwood, J. A.; Heikkila, B. (15 May 2002). "The effect of the July 14, 2000 "Bastille Day" solar flare event on >70 MeV galactic cosmic rays observed at V1 and V2 in the distant heliosphere". Geophysical Research Letters. 29 (10): 15–1–15-3. doi:10.1029/2002GL014729. Retrieved 7 August 2022.

External links[edit]