The Bastille Day solar storm was a powerful

solar storm A solar storm is a disturbance on the Sun, which can emanate outward across the heliosphere, affecting the entire Solar System, including Earth and its magnetosphere, and is the cause of space weather in the short-term with long-term patterns compr ...

on 14–16 July 2000 during the

solar maximum Solar maximum is the regular period of greatest solar activity during the Sun's 11-year solar cycle. During solar maximum, large numbers of sunspots appear, and the solar irradiance output grows by about 0.07%. On average, the solar cycle take ...

solar cycle 23 Solar cycle 23 was the 23rd solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 12.6 years, beginning in August 1996 and ending in December 2008. The maximum smoothed sunspot number observed d ...

. The storm began on the national day of

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

Bastille Day Bastille Day is the common name given in English-speaking countries to the national day of France, which is celebrated on 14 July each year. It is referred to, both legally and commonly, as () in French, though ''la fête nationale'' is also u ...

. It involved a

solar flare A solar flare is a relatively intense, localized emission of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and ot ...

, a

solar particle event In solar physics, a solar particle event (SPE), also known as a solar energetic particle event or solar radiation storm, is a solar phenomenon which occurs when particles emitted by the Sun, mostly protons, become accelerated either in the Sun's ...

, and a

coronal mass ejection A coronal mass ejection (CME) is a significant ejection of plasma mass from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understandin ...

which caused a severe

geomagnetic storm A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth's magnetosphere that is driven by interactions between the magnetosphere and large-scale transient Plasma (physics), plasma and magnetic field structur ...

Overview

Solar flare and particle event

On 14 July 2000 from about 10:03 to 10:43

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

GOES The Geostationary Operational Environmental Satellite (GOES), operated by the United States' National Oceanic and Atmospheric Administration (NOAA)'s National Environmental Satellite, Data, and Information Service division, supports weather fo ...

satellites detected a very strong, X5.7-class solar flare which peaked in

soft X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

intensity at around 10:24 UTC. This flare originated from the solar

active region In solar physics and observation, an active region is a temporary feature in the Sun's atmosphere characterized by a strong and complex magnetic field. They are often associated with sunspots and are commonly the source of violent eruptions suc ...

AR9077 which was located near the center of the Sun's disk (N22 W02) at the time of the flare. Starting at around 10:41 UTC, GOES satellites began detecting a strong, S3,

associated with the ongoing X5.7-class flare. This resulted in high energy protons penetrating and ionizing parts of the Earth's

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...

and creating

noise Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrat ...

in various satellite imaging systems such as in the EIT and LASCO instruments. Some of these particles had sufficient energy to generate effects measured on Earth's surface, an event referred to as a

ground level enhancement A Ground Level Enhancement or Ground Level Event (GLE), is a special subset of solar particle event where charged particles from the Sun have sufficient energy to generate effects which can be measured at the Earth's surface. These particles (mos ...

. Although the flare was not extremely large, the associated solar particle event was the fourth largest since 1967.

Geomagnetic storm

The detection of the solar flare was also followed by the detection of a halo, or Earth-directed,

(CME) in

coronagraph A coronagraph is a telescopic attachment designed to block out the direct light from a star or other bright object so that nearby objects – which otherwise would be hidden in the object's bright glare – can be resolved. Most coronagr ...

data starting at 10:54 UTC. This CME reached Earth on 15 July causing a

on 15–16 July which would reach a peak

Kp index The ''K''-index quantifies disturbances in the horizontal component of Earth's magnetic field with an integer in the range 0–9 with 1 being calm and 5 or more indicating a geomagnetic storm. It is derived from the maximum fluctuations ...

of 9+ in the late hours of 15 July corresponding to an extreme-level, or G5, geomagnetic storm and register a peak

Dst Daylight saving time (DST), also referred to as daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to make better use of the long ...

of −301 nT. The storm caused minor damage to power transformers and satellites. It was also one of only three solar storms having registered a maximum Kp of 9+ since the

March 1989 geomagnetic storm The March 1989 geomagnetic storm occurred as part of severe to extreme solar storms during early to mid March 1989, the most notable being a geomagnetic storm that struck Earth on March 13. This geomagnetic storm caused a nine-hour outage of Hyd ...

, the others being the 2003 Halloween solar storms and the May 2024 solar storms.

Aftermath

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. Despite their great distance from the Sun, the Bastille Day event was observed by ''

Voyager 1 ''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and the interstellar medium, interstellar space beyond the Sun's heliosphere. It was launched 16 days afte ...

'' and ''

Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, as a part of the Voyager program. It was launched on a trajectory towards the gas giants (Jupiter and Saturn) and enabled further encounters with the ice giants (Uranus and ...

''.

Notes

References

External links

'Bastille Day' Flare Animations

Propagation of Bastille Day Event to Voyagers 1 & 2

High-Energy Ions Energized by Bastille Day 2000 Shock Bombardment

Ulysses Observations of Solar Energetic Particles From the Bastille Day Event
{{Solar storms Geomagnetic storms 2000 in science July 2000 2000 natural disasters