Solar cycle 24 is the most recently completed solar cycle, the 24th since 1755, when extensive recording of solar sunspot activity began.[1][2] It began in December 2008 with a minimum smoothed sunspot number of 2.2,[3][failed verification] and ended in December 2019.[4] Activity was minimal until early 2010.[5][6] It reached its maximum in April 2014 with a 23 months smoothed sunspot number of 81.8.[7] This maximum value was substantially lower than other recent solar cycles, down to a level which had not been seen since cycles 12 to 15 (1878-1923).
Solar cycle 24 | |
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Sunspot data | |
Start date | December 2008 |
End date | December 2019 |
Duration (years) | 11.0 |
Max count | 81.8 |
Max count month | April 2014 |
Min count | 2.2 |
Spotless days | 489 |
Cycle chronology | |
Previous cycle | Solar cycle 23 (1996-2008) |
Next cycle | Solar cycle 25 (2019-present) |
Predictions
editPrior to the minimum between the end of Solar Cycle 23 and the beginning of Solar Cycle 24, two theories predicted how strong Solar Cycle 24 would be. One camp postulated that the Sun retained a long memory (Solar Cycle 24 would be active) while the other asserted that it had a short memory (quiet). Prior to 2006, the difference was substantial with a minority of researchers predicting "the smallest solar cycle in 100 years."[8] Another group of researchers, including one at NASA, predicted that it "looks like its going to be one of the most intense cycles since record-keeping began almost 400 years ago."[9]
The delayed onset of high latitude spots indicating the start of Solar Cycle 24 led the "active cycle" researchers to revise their predictions downward and the consensus by 2007 was split 5-4 in favor of a smaller cycle.[10] By 2012, consensus was a small cycle, as solar cycles are much more predictable 3 years after minima.
In May 2009 the NOAA Space Weather Prediction Center's Solar Cycle 24 Prediction Panel predicted the cycle to peak at 90 sunspots in May 2013.[11] In May 2012 NASA's expert David Hathaway predicted a peak in Spring of 2013 with about 60 sunspots.[12]
NASA funded and used Ken Schatten's physics-based models,[13] which utilized a solar Dynamo model, to accurately predict the low. This method used the correlation between solar magnetic field strength at solar minimum to sunspot number at solar maximum to accurately predict the peak solar flux of each of the last three solar cycles. Schatten's predictions become accurate as early as solar minima, 5–6 years before solar max.
Results
editIn early 2013, after several months of calm, it was obvious that the active 2011 was not a prelude to a widely predicted late 2012-early 2013 peak in solar flares, sunspots and other activity. This unexpected stage prompted some scientists to propose a "double-peaked" solar maximum, which then occurred. The first peak reached 99 in 2011 and the second peak came in early 2014 at 101.[14]
Speculation
editAccording to NASA, the intensity of geomagnetic storms during Solar Cycle 24 may be elevated in some areas where the Earth's magnetic field is weaker than expected. This fact was discovered by the THEMIS spacecraft in 2008.[15][16] A 20-fold increase in particle counts that penetrate the Earth's magnetic field may be expected.[17] Solar Cycle 24 has been the subject of various hypotheses and commentary pertaining to its potential effects on Earth.
While acknowledging that the next solar maximum will not necessarily produce unusual geomagnetic activity, astrophysicist Michio Kaku took advantage of the media focus on the 2012 phenomenon to draw attention to the need to develop strategies for coping with the terrestrial damage that such an event could inflict. He asserted that governments should ensure the integrity of electrical infrastructure, so as to prevent a recurrence of disruption akin to that caused by the solar storm of 1859.[18]
The current solar cycle is currently the subject of research, as it is not generating sunspots in the expected manner. Sunspots did not begin to appear immediately after the last minimum (in 2008) and although they started to reappear in late 2009, they were at significantly lower rates than anticipated.[19]
On April 19, 2012, the National Astronomical Observatory of Japan predicted that the Sun's magnetic field would assume a quadrupole configuration.[20]
Throughout 2012, NASA posted news releases discrediting the 2012 phenomenon and the so-called Mayan prophecy, delinking them from solar activity and space weather.[21][22]
Events
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Class | Year | Date | Sunspot region | Radio B. | SR Storm | CME | GM Storm | ||
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X9.33 | 2017 | Sep 6 | 2673 | R3 | S1 | Yes | - | ||
X8.2 | 2017 | Sep 10 | 2673 | R3 | S3 | Yes | - | ||
X6.9 | 2011 | Aug 9 | 1263 | R3 | S1 | Yes | - | ||
X5.4 | 2012 | Mar 7 | 1429 | R3 | S3 | Yes | G3 | ||
X4.9 | 2014 | Feb 25 | 1990 | R3 | S1 | Yes | G2 | ||
X3.3 | 2013 | Nov 5 | 1890 | R3 | - | Yes | - | ||
X3.2 | 2013 | May 14 | 1748 | R3 | - | Yes | - | ||
X3.19 | 2014 | Oct 24 | 2192 | R3 | - | No | - | ||
X2.8 | 2013 | May 13 | 1748 | R3 | - | Yes | - | ||
X2.74 | 2015 | May 5 | 2339 | R3 | - | Yes | - | ||
X2.3 | 2013 | Oct 29 | 1875 | R3 | - | Yes | - | ||
X2.2 | 2011 | Feb 15 | 1158 | R3 | - | Yes | G1 | ||
X2.2 | 2014 | Jun 10 | 2087 | R3 | - | ? | - | ||
X2.2 | 2015 | Mar 11 | 2297 | R3 | - | Yes | - | ||
X2.2 | 2017 | Sep 6 | 2673 | R3 | - | ? | - | ||
X2.1 | 2013 | Oct 25 | 1882 | R3 | - | Yes | - | ||
X2.1 | 2011 | Sep 6 | 1283 | R3 | S1 | Yes | G3 | ||
X2.0 | 2014 | Oct 26 | 2192 | R3 | - | No | - | ||
X2.0 | 2014 | Oct 27 | 2192 | R3 | - | No | - | ||
X1.9 | 2011 | Nov 3 | 1339 | R3 | - | Yes | - | ||
X1.9 | 2011 | Sep 24 | 1302 | R3 | S1 | Yes | G4 | ||
X1.8 | 2011 | Sep 7 | 1283 | R3 | S1 | Yes | G1 | ||
X1.8 | 2012 | Oct 23 | 1598 | R3 | - | No | - | ||
X1.8 | 2014 | Dec 20 | 2242 | R3 | - | Yes | - | ||
X1.7 | 2013 | Oct 25 | 1882 | R3 | - | Yes | - | ||
X1.7 | 2012 | Jan 27 | 1402 | R3 | S2 | Yes | - | ||
X1.7 | 2013 | May 13 | 1748 | R3 | - | Yes | - | ||
X1.66 | 2014 | Sep 10 | 2158 | R3 | S2 | Yes | G3 | ||
X1.6 | 2014 | Oct 22 | 2192 | R3 | - | No | - | ||
X1.5 | 2011 | Mar 9 | 1166 | R3 | - | Yes | G2 | ||
X1.5 | 2014 | Jun 10 | 2087 | R3 | - | ? | - | ||
X1.4 | 2011 | Sep 22 | 1302 | R3 | - | Yes | - | ||
X1.4 | 2012 | Jul 12 | 1520 | R3 | S1 | Yes | G2 | ||
X1.3 | 2012 | Mar 7 | 1430 | R3 | S3 | No | - | ||
X1.3 | 2014 | Apr 25 | 2035 | R3 | - | ? | - | ||
X1.3 | 2017 | Sep 7 | 2673 | R3 | S2 | No | G4 | ||
X1.2 | 2014 | Jan 7 | 1944 | R3 | S2 | Yes | - | ||
X1.2 | 2013 | May 15 | 1748 | R3 | S1 | Yes | G1 | ||
X1.1 | 2012 | Mar 5 | 1429 | R3 | - | Yes | G2 | ||
X1.1 | 2012 | Jul 6 | 1515 | R3 | S1 | Yes | G1 | ||
X1.1 | 2013 | Nov 8 | 1890 | R3 | - | Yes | - | ||
X1.1 | 2013 | Nov 10 | 1890 | R3 | - | Yes | - | ||
X1.1 | 2014 | Oct 19 | 2192 | R3 | - | No | - | ||
X1.0 | 2013 | Nov 19 | 1893 | R3 | S1 | Yes | - | ||
X1.0 | 2013 | Oct 28 | 1875 | R3 | S1 | Yes | - | ||
X1.0 | 2014 | Mar 29 | 2017 | R3 | - | ? | - | ||
X1.0 | 2014 | Jun 11 | 2087 | R3 | - | ? | - | ||
X1.0 | 2014 | Oct 25 | 2192 | R3 | - | No | - | ||
M9.9 | 2014 | Jan 1 | 1936 | R2 | - | Yes | - | ||
M9.3 | 2013 | Oct 24 | 1877 | R2 | - | Yes | - | ||
M9.3 | 2011 | Aug 4 | 1261 | R2 | S1 | Yes | G4 | ||
M9.3 | 2011 | Jul 30 | 1260 | R2 | - | No | - | ||
M9.3 | 2014 | Mar 12 | 1996 | R2 | - | ? | - | ||
M9.2 | 2015 | Mar 7 | 2339 | R2 | - | Yes | - | ||
M9.0 | 2012 | Oct 20 | 1598 | R2 | - | Yes | - | ||
M8.7 | 2012 | Jan 23 | 1402 | R2 | S3 | Yes | G1 | ||
M8.7 | 2014 | Oct 22 | 2192 | R2 | - | No | - | ||
M8.7 | 2014 | Dec 17 | 2242 | R2 | - | Yes | - | ||
M8.4 | 2012 | Mar 10 | 1429 | R2 | - | Yes | - | ||
M8.3 | 2010 | Feb 12 | 1046 | R2 | - | Yes | - | ||
M8.2 | 2015 | Mar 3 | 2290 | R2 | - | Yes | - | ||
M8.1 | 2017 | Sep 8 | 2673 | R2 | - | ? | - | ||
M7.9 | 2012 | Mar 13 | 1429 | R2 | S2 | Yes | G2 | ||
M7.9 | 2014 | Nov 5 | 2205 | R2 | - | Yes | - | ||
M7.9 | 2015 | Jun 25 | 2371 | R2 | S1 | Yes | G2 | ||
M7.7 | 2012 | Jul 19 | 1520 | R2 | - | Yes | - | ||
M7.6 | 2015 | Sep 28 | 2422 | R2 | - | ? | - | ||
M7.6 | 2016 | Jul 23 | 2567 | R2 | - | Yes | - | ||
M7.4 | 2011 | Sep 25 | 1302 | R2 | - | Yes | G1 | ||
M7.3 | 2014 | Apr 18 | 2036 | R2 | S1 | ? | - | ||
M7.3 | 2014 | Oct 2 | 2173 | R2 | - | Yes | - | ||
M7.3 | 2017 | Sep 7 | 2673 | R2 | - | ? | - | ||
M7.2 | 2014 | Jan 7 | 1944 | R2 | - | No | - | ||
M7.1 | 2011 | Sep 24 | 1302 | R2 | - | Yes | G4 | ||
M7.1 | 2014 | Oct 27 | 2192 | R2 | - | ? | - | ||
M6.9 | 2012 | Jul 8 | 1515 | R2 | S1 | Yes | - | ||
M6.9 | 2014 | Dec 18 | 2241 | R2 | - | Yes | |||
M6.7 | 2011 | Sep 8 | 1283 | R2 | - | Yes | G1 | ||
M6.7 | 2014 | Oct 27 | 2192 | R2 | - | ? | - | ||
M6.7 | 2016 | Apr 18 | 2529 | R2 | - | Yes | - | ||
M6.6 | 2011 | Feb 13 | 1158 | R2 | - | Yes | - | ||
M6.6 | 2011 | Feb 18 | 1158 | R2 | - | No | - | ||
M6.6 | 2014 | Jan 30 | 1967 | R2 | - | Yes | - | ||
M6.6 | 2014 | Oct 28 | 2192 | R2 | - | ? | - | ||
M6.6 | 2015 | Jun 22 | 2371 | R2 | S2 | Yes | G4 | ||
M6.5 | 2013 | Apr 11 | 1719 | R2 | S2 | Yes | - | ||
M6.5 | 2014 | Apr 2 | 2027 | R2 | - | ? | - | ||
M6.5 | 2014 | Jul 8 | 2113 | R2 | - | ? | - | ||
M6.5 | 2014 | Nov 3 | 2205 | R2 | S1 | Yes | - | ||
M6.4 | 2010 | Feb 7 | 1045 | R2 | - | Yes | - | ||
M6.4 | 2013 | Dec 31 | 1936 | R2 | - | Yes | - | ||
M6.3 | 2013 | Nov 1 | 1884 | R2 | - | Yes | - | ||
M6.3 | 2012 | Mar 9 | 1429 | R2 | - | Yes | G2 | ||
M6.1 | 2012 | Jul 5 | 1515 | R2 | - | No | - | ||
M6.1 | 2012 | Jul 28 | 1532 | R2 | - | Yes | - | ||
M6.1 | 2014 | Dec 4 | 2222 | R2 | - | Yes | - | ||
M6.0 | 2012 | Nov 13 | 1613 | R2 | - | Yes | - | ||
M6.0 | 2011 | Aug 3 | 1261 | R2 | - | Yes | G4 | ||
M5.9 | 2013 | Jun 7 | 1762 | R2 | - | Yes | - | ||
M5.9 | 2014 | Aug 24 | 2151 | R2 | - | ? | - | ||
M5.8 | 2011 | Sep 24 | 1302 | R2 | - | ? | - | ||
M5.8 | 2015 | Mar 9 | 2297 | R2 | - | Yes | - | ||
M5.7 | 2012 | May 10 | 1476 | R2 | - | Yes | - | ||
M5.7 | 2013 | May 3 | 1739 | R2 | - | Yes | - | ||
M5.7 | 2014 | Nov 16 | 2209 | R2 | - | ? | - | ||
M5.7 | 2017 | Apr 2 | 2644 | R2 | - | No | - | ||
M5.6 | 2012 | Jul 2 | 1515 | R2 | - | Yes | - | ||
M5.6 | 2015 | Jan 13 | 2257 | R2 | - | No | - | ||
M5.6 | 2015 | Aug 24 | 2403 | R2 | - | ? | - | ||
M5.5 | 2012 | Aug 18 | 1548 | R2 | - | No | - | ||
M5.5 | 2015 | Oct 2 | 2422 | R2 | - | ? | - | ||
M5.5 | 2016 | Jul 23 | 2567 | R2 | - | Yes | - | ||
M5.5 | 2017 | Sep 4 | 2673 | R2 | - | ? | - | ||
M5.4 | 2010 | Nov 6 | 1121 | R2 | - | ? | - | ||
M5.4 | 2014 | Nov 6 | 2205 | R2 | - | ? | - | ||
M5.3 | 2011 | Sep 6 | 1283 | R2 | - | Yes | G3 | ||
M5.3 | 2011 | Mar 8 | 1165 | R2 | - | Yes | G1 | ||
M5.3 | 2012 | Jul 4 | 1515 | R2 | - | Yes | - | ||
M5.3 | 2014 | May 8 | 2056 | R2 | - | ? | G1 | ||
M5.3 | 2017 | Apr 2 | 2644 | R2 | - | No | - | ||
M5.2 | 2014 | Feb 4 | 1967 | R2 | - | ? | - | ||
M5.1 | 2012 | May 17 | 1476 | R2 | S2 | Yes | - | ||
M5.1 | 2013 | Oct 28 | 1875 | R2 | - | Yes | - | ||
M5.1 | 2014 | Sep 28 | 2173 | R2 | - | Yes | - | ||
M5.1 | 2015 | Mar 10 | 2297 | R2 | - | Yes | - | ||
Source: Solarham.com[23] and NOAA's SWPC.[24] The CME field indicates whether the solar flare hurled a CME (oriented or not to Earth). The Radio B./SR Storm/GM Storm fields indicate the NOAA scales of radio blackouts/solar radiation storms/geomagnetic storms, being G1 (minor), G2 (moderate), G3 (strong), G4 (severe) and G5 (extreme). |
2008
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On 4 January 2008, an active region appeared with magnetic polarity reversed compared to that expected by Hale's law for solar cycle 23. This presaged the start of solar cycle 24—though did not mark its official beginning. The region was located at the relatively high latitude 30° N which, according to Spörer's law, provided further evidence for the arrival of cycle 24. The NOAA assigned it the active region number AR10981.[5]
Only a few sunspots were observed on the surface of the Sun throughout 2008. The smoothed monthly sunspot number reached a minimum of 2.2 in December 2008, therefore an international panel of scientists declared that month as solar minimum and the beginning of Solar Cycle 24.[26]
2009
edit2.5
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Solar activity remained extremely low throughout 2009. The observed monthly sunspots exceeded 10 only in December.
2010
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On 19 January 2010, active region AR11041 produced an M2.3-class flare, the first flare of cycle 24 above M-class. It was followed by an M1.7-class flare seven hours later and four consecutive M-class flares the next day. Among the four flares, the strongest reached a strength of M3.4.
On 12 February 2010, active region AR11046 produced an M8.3-class flare. Later in the month, active regions AR11045 and AR11046 unleashed a total of nine M-class flares.
On 5 April 2010, the first coronal mass ejection (CME) of cycle 24 erupted at an active region causing a G3 (strong) geomagnetic storm on Earth. The Kp index, which quantifies disturbances in the horizontal component of Earth's magnetic field, reached a value of 7.
On 1 and 2 August 2010, a series of four large CMEs were observed erupting from the Sun's Earth-facing side.[29] These CMEs were likely connected to a C3.2-class flare from active region AR11092 despite the CMEs taking place about 400,000 km apart from the region.[30] On 4 August 2010, a G2 (moderate) geomagnetic storm caused aurorae to be visible in the northern hemisphere at latitudes as far south as 45° N near Michigan and Wisconsin in the United States, and Ontario, Canada. European observers reported sightings as far south as Denmark near latitude 56° N. The aurorae were reportedly green in color due to the interaction of the solar particles with oxygen atoms in the relatively denser atmosphere of southern latitudes.[31][32]
On 14 August 2010, a C4.4-class flare produced the first solar radiation storm of cycle 24. The proton storm event was minor, rating at S1, and was easily absorbed by the Earth's ionosphere.
On 6 November 2010, active region AR11121 emitted an M5.4 flare.[33]
2011
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February
edit'Valentine’s Day' 2011 flare
editPeaking at 01:56 UT on February 15, 2011, sunspot group 1158 produced an X2.2-class solar flare. Dubbed the Valentine's Day solar event by the scientific community, it was the first Solar Cycle 24 flare reaching X class level. In fact, it was the first of its class since December 2006. NOAA issued an R3 (strong) radio blackout alert pertaining this prominent x-ray flux event. In addition to flashing Earth with X and UV radiation, the explosion also hurled a CME in Earth's direction. The magnetosphere was impacted on February 18. The CME struck a minor G1-level geomagnetic storm.[35][36]
Shortly before, on February 13, sunspot 1158 had unleashed an M6.6-class solar flare. On February 18, the same active region produced another x-ray burst with the same strength.[37] 13 M-class bursts were registered in February 2011.
March
editA CME exploded from the vicinity of sunspot 1164 during the late hours of March 7, 2011. It leapt away from the Sun traveling ~2200 km/s, making it the fastest CME since September 2005.
On March 9, active region 1166 erupted in an X1.5 flare. An R3-level radio blackout was reported. The related CME caused a G2 geomagnetic storm two days later.[38] 21 M-class flares were registered this month.
July
editSunspot 1260 produced an M9.3-class solar flare on July 30, 2011. Because of its brevity, the eruption did not hurl a substantial cloud of ionized material or CME toward Earth, so it was not geoeffective.[39]
August
editOn August 5, 2011, the combined cloud of three consecutive CMEs produced brilliant aurorae, reported as far south as Oklahoma and Alabama. The geomagnetic storm reached a G4 (severe) level, enough to create power outages. It was one of the strongest geomagnetic storms in years. In the southern hemisphere, aurorae could be seen as far north as South Africa, Southern Chile and Southern Australia. The CMEs were hurled by three M-class flares erupting in active sunspot 1261: M1.4 on August 2, M6.0 on August 3 and M9.3 on August 4.[40][41][42]
X6.9-class flare
editOn August 9 at 08:05 UT, sunspot 1263 produced a massive X6.9-class solar flare, the third X-flare of Solar Cycle 24 and the most powerful so far (as of May 2013). There was also a CME associated with this burst. Although the flare was not Earth-directed, radiation created waves of ionization in Earth's upper atmosphere, briefly disrupting communications at some VLF and HF radio frequencies. An R3-level (strong) radio blackout alert was issued. A proton event greater than 10 MeV (million electron volts) and exceeding 10 pfu (proton flux units) was also reported, so an S1-level solar radiation storm was also issued.[43]
September
editSunspot 1283 erupted with an M5.3-class solar flare on September 6 at 01:50 UT. An R2 (moderate) blackout radio alert was issued. The burst was Earth-directed. Just 21 hours later, an X2.1-class flare – some four times stronger than the earlier flare – erupted from the same sunspot region. NOAA detected an R3 (strong) radio blackout and an S1 (minor) solar radiation storm. The combined CMEs of these bursts arrived at Earth on September 9, provoking a G3 (strong) geomagnetic storm.
The next day, September 7, an X1.8-class solar flare erupted from sunspot 1283, producing an S1 solar radiation storm. A fourth flare, an M6-class, was ejected by the same sunspot on September 8.[44][45][46]
This sequence of flares produced waves of ionization in Earth's upper atmosphere, briefly altering the propagation of low-frequency radio signals around Earth. Moreover, the eruptions hurled clouds of plasma in its direction. CME impacts, strong geomagnetic storms and aurorae were registered from September 9 onwards.
Then, on September 22, an X1.4-class solar flare erupted out of sunspot 1302. An R3-level radio blackout was registered. The blast produced a significant CME, but was not Earth directed. Two days later, an X1.9-class flare, followed in the next 31 hours by a spectacular string of 14 M-class flares, the biggest being two M7 flares, was mostly unleashed out of the same sunspot. The first two explosions, X1.9 and M7.1, propelled a pair of closely spaced CMEs. A G4 (severe) geomagnetic storm was reported on September 26.[47][48]
In total, the Sun produced four X flares and 31 M flares in September 2011, one of the most active months of Solar Cycle 24 so far.
October
editThe Sun unleashed eight M-class flares this month, being the strongest the M3.9 event, followed by an Earth-directed CME, produced by sunspot 1305 on October 2. Just in the eve, sunspots 1302 and 1305 had emitted flares almost at the same time; the first event was a C-class and the second one reached a M1.2 category. This double eruption, which hurled a double CME as well, were particularly interesting as coincided with the arrival of a comet, discovered by amateur astronomers the previous day, that disintegrated in spectacular fashion when it plunged into the Sun. A very similar scenario happened on May 10–11, 2011.[49]
November
editOn November 3, 2011, active region 1339, one of the largest sunspots in years - 40,000 km wide and at least twice that in length - unleashed an X1.9-class solar flare. Waves of ionization in the upper atmosphere created an R3 (strong) radio blackout. The related CME was not headed for Earth.[50] 13 M-class flares were registered this month. November 2011 may be considered the most active month of the current Cycle 24 so far, as monthly sunspot count was nearly 100 (96.7) and the same went for the F10.7 Solar Flux (the radio emission from the Sun at a wavelength of 10.7 cm) that racked up a value of 153.1. However, these numbers are well below those of Cycle 23 at its peak. Cycle 23 peak sunspot count was 170 and its F10.7 was about 235.[51]
December
editSolar activity increased again in late December, with the Sun unleashing eight M-flares. The most intense flare, produced by sunspot 1385, was an M4.0 event on December 25.[52] The year 2011 ended up with 111 M-class and 8 X-class solar flares.[53]
2012
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January
editActive sunspot 1401 erupted an M3.2-class solar flare and a full-halo CME on January 19, 2012. The CME hit the Earth's magnetic field in the early hours of January 22, with minor geomagnetic disturbances reported.[55]
Sunspot 1402 erupted a long-duration M8.7-class flare, followed by a CME, on January 23, 2012, at 03:59 UTC. According to NOAA, the flare's radiation storm was ranked as S3 (strong), the strongest since May 2005.[56] The very fast-moving CME arrived at the Earth on January 24 at approximately 15:00 UTC. The geomagnetic storm reached a G1 level (minor), the same level recorded by the previous M3-class flare.[57]
On January 27, at 18:37 UT, sunspot region 1402 unleashed an X1.7-class flare, prompting NOAA's Space Weather Prediction Center to issue an R3 (strong) Radio Blackout warning and an S2 (moderate) Solar Radiation Storm warning. Sunspot 1402 was rotating onto the far side of the Sun, so the blast site was not facing Earth. The explosion also produced a huge CME, but not Earth-oriented, so no geomagnetic storm was expected.[58][59]
March
editFollowing several minor C-class flares, M-class flares and CMEs registered in previous days and weeks, active region 1429 erupted an X1.1-class flare on March 5 at 04:13 GMT. The wave of high energy electromagnetic rays, reaching Earth in minutes, caused an R3 (strong) radio blackout over China, India and Australia, according to NOAA. Sunspot region 1429, whose size was half of that of Jupiter and was rotating toward Earth, was being particularly active since it materialized on March 2. The CME that followed arrived at the Earth on March 7 and caused a G2 (moderate) geomagnetic storm. Just hours after ejecting the X1.1-class flare, it produced several minor C and M-class flares in quick succession.[60][61]
X5.4-class flare
editAfter releasing up to nine M-class flares in only one day, the active region 1429 erupted a powerful X5.4-class flare at 00:24 UTC on March 7. The related CME impacted the Earth on March 8, causing a G3 (strong) geomagnetic storm. This event marked the second strongest solar flare of Cycle 24 in terms of X-ray flux. NOAA launched R3 (strong) radio blackout and S3 (strong) solar radiation storm alerts.[62] Just one hour after that first flare, nearby sunspot 1430 released a less powerful X1.3-class flare. No CME associated to this event was reported.[63] Months later, in June, NASA reported that its Fermi Gamma-ray Space Telescope detected in this powerful flare the highest flux of gamma rays — greater than 100 MeV — ever associated with an eruption on the Sun.[64]
AR1429, rotating toward the other side of the Sun, generated an M6.3-class flare on March 9, an M8.5 flare one day later and an M7.9 flare on March 13. These eruptions hurled CMEs, all Earth-oriented. The first wave of plasma impacted the magnetosphere on March 12, causing a G2 (moderate) geomagnetic storm. The second CME was not geoeffective. The third wave of ionized gas reached Earth on March 15, causing another G2 storm.
In late March, the US Air Force Space Command reported that the solar storms of March 7–10 could have temporarily knocked American military satellites offline.[65] NASA also reported that these powerful flares heated the Earth's upper atmosphere with the biggest dose of infrared radiation since 2005. From March 8 to March 10, the thermosphere absorbed 26 billion kWh of energy. Infrared radiation from carbon dioxide and nitric oxide, the two most efficient coolants in the thermosphere, re-radiated 95% of that total back into space.[66]
March 2012, one of the most active months of Solar Cycle 24, ended up with 19 M-class and three X-class flares.
April
editA prominent eruption produced a CME off the east limb (left side) of the Sun on April 16, 2012.[67] Such eruptions are often associated with solar flares, and in this case an M1.7-class (medium-sized) flare occurred at the same time, peaking at 1:45 PM EDT (17.45 UTC).[67] The CME was not aimed toward Earth.[67] Nevertheless, this month was very quiet in comparison to the previous one, as only two M-class flares were recorded.
May
editSolar activity increased again this month, with 12 M-class flares ejected, the strongest being an M5.7 flare produced by active region 1476 on May 10. This so-called "monster" sunspot complex, the largest active region of the cycle to date, was about the size of Jupiter, or eleven times the diameter of Earth.[68]
June
edit11 M-class solar flares were observed this month, the largest being an M3.3 flare.
July
editAn X1.1-class flare erupted from sunspot 1515 on July 6, generating an R3 (strong) radio blackout and an S1 (minor) solar storm; its related CME caused a G1 (minor) geomagnetic storm. Six days after, sunspot 1520, the largest active region of Solar Cycle 24 to date, unleashed an X1.4-class flare, peaking at 12:52 PM EDT. This huge group of sunspots, which rotated into view on July 6, was located in the center of the Sun at the time of this event. The related CME caused a G2 (moderate) geomagnetic storm, following an R3 radio blackout and an S1 solar storm.[69]
The Sun emitted a moderate solar flare on July 19, 2012, beginning at 1:13 AM EDT and peaking at 1:58 AM. The flare was classified as an M7.7 flare. It was also emitted from sunspot 1520.[70] Other M-class flares registered this month included an M6.9 (July 8, sunspot 1515), an M6.1 (July 5, sunspot 1515), an M6.1 (July 28, sunspot 1532), an M5.6 (July 2, sunspot 1515) and an M5.3 (July 4, sunspot 1515). The month ended up with 45 M-class flares and 2 X-class flares, which is the highest number of such flares within the current solar cycle to date. Nevertheless, July 2012 was not the most active month in solar radio flux and number of sunspots.
Solar storm of 2012
editAugust
editOn August 31, 2012, a long filament of solar material that had been hovering in the Sun's atmosphere (the corona) erupted out into space at 4:36 p.m. EDT.[71] The CME traveled at over 1500 km (900 miles) per second. The CME did not travel directly toward Earth, but did connect with Earth's magnetic environment, or magnetosphere, with a glancing blow. causing aurorae to appear on the night of Monday, September 3.[71] A G2 (moderate) geomagnetic storm was registered on September 3 and September 5.[72] The Sun erupted 10 M-class flares this month, the largest being an M5.5 burst ejected on August 18.
September
editA filament eruption occurred during the late hours of September 27, resulting in a brief S1 (minor) radiation storm, alerted by NOAA in the early hours of the next day. The Earth-directed CME associated with this event affected Earth on September 30. A G3 geomagnetic storm was registered on October 1. The filament eruption was connected to a C3.7 flare which occurred in the vicinity of sunspot 1577.[73] Solar activity decreased remarkably this month. 4 minor solar flares, below M2, were registered in September 2012.
October
editOn October 8 and 9, the arrival of a CME unrelated to solar flares and emitted on October 5 caused disturbances in the horizontal component of the Earth's magnetic field. The planetary Kp-index reached level 6, so a G2 (moderate) geomagnetic storm was reported.[74] The Sun released an M9.0 flare on October 20. This was followed three days later on October 23 by a very impulsive flare, peaking as an X1.8-class event at 3:17 a.m. UTC.[75][76] Both flares came from active region 1598, located on the left side (east) of the sun, which had previously been the source of a number of weaker flares. The M9.0 burst occurred when the sunspot was not yet rotated onto the Earth-facing side of the solar disk.[75] The NOAA categorized the radio blackout associated with the X1.8 event as an R3.[75] This was the 7th and last X-class flare in 2012.[75] There was no associated Earth-directed CME.[75]
November
edit14 M-class flares were registered this month, the strongest being an M6.0 flare, which erupted on November 13 by AR1613.[77]
December
editSolar activity decreased significantly this month. For first time in two years (since December 2010), no X or M-class flares were emitted by the Sun's Earth-facing side (the strongest flare was merely a C4.1). The observed sunspots were 40.8 and the 10.7 cm radio flux value was 108.4, the lowest in ten months.[78]
2012 ended up with 129 M-class and 7 X-class solar flares.[53]
2013
edit50
100
150
200
250
300
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
April
editThe unexpectedly low solar activity continued in April 2013. Only 13 M-class flares were reported from December 2012 to April 2013, the strongest being an M6.5 unleashed by active region 1719 on the 11th. This event generated an R2 radio blackout and an R2 radiation storm. The observed sunspots this month were 72.4 and the 10.7 cm radio flux value was 125.0.[78][80]
May
editString of X-class flares
editSolar activity increased rapidly in mid-May 2013 with four consecutive strong flares in two days. These powerful bursts all surged from the just-numbered sunspot AR1748, located on the eastern limb of the Sun and barely rotating around the front of the solar disk. AR1748 emitted the first flare, an X1.7-class, on May 13, peaking at 02:17 UTC. This event was quickly followed the same day at 16:09 UTC by an X2.8-class flare. On May 14 at 01:17 UTC the same sunspot emitted an X3.2-class flare, the third strongest of the current solar cycle so far. This was followed by an X1.2-class flare at 01:52 UTC on May 15. The four X-ray bursts generated an R3 (strong) radio blackout in the upper atmosphere.
Every X-ray event was followed by a CME. The first three CMEs were not geoeffective at all as they were not directed toward Earth; the fourth CME was partially geoeffective, so a G1 (minor) geomagnetic storm was expected to occur on May 18. An S1 (minor) proton storm event was also detected in connection with the May 15 X1.2 flare.[81]
2014
edit50
100
150
200
250
300
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
February
editOn February 24, 2014, the sun erupted with an X4.9-class solar flare, the strongest of that year.[83]
October
editFour solar flares occurred within 5 days from sunspot AR 12192, which is both the largest sunspot of solar cycle 24 and the largest since 1990. On October 19 there was a major X1.1-class solar flare. On October 22 an M8.7-class flare was followed by an X1.6 event. The October 24 X3.1-class solar flare was strong enough to trigger a radio blackout. Larger than the planet Jupiter, the AR 12192 sunspot was visible during a partial solar eclipse seen in North America.[83]
2015
edit50
100
150
200
250
300
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
June
editThe sun emitted a mid-level solar flare, an M7.9-class, peaking at 4:16 a.m. EDT on June 25, 2015.[85]
November
editIn early November 2015, solar flares disrupted the air traffic control system in central and southern Sweden, causing heavy delays for passengers.[86]
2016
edit25
50
75
100
125
150
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
December
editA sunspot group originally attributed to the new solar cycle 25 is observed.[88] The sunspot numbers continue to decline.
During 2016, there were 26 days with no sunspots (preliminary numbers).[89]
2017
edit10
20
30
40
50
60
70
80
90
100
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
March
editAs of 31 March, preliminary reports indicate there had been 24 days during 2017 during which there were no sunspots.[89]
September
editOn 6 September the largest X-class flare in a decade (X9.3) erupted from active region 2673.[91][92] Then, when this region was just crossing the west limb, another X-class flare (SOL2017-09-10, X8.2) produced only the second ground-level particle event of the cycle.[93] Sunspot region 2673 was one of the most active regions during the entire cycle, creating both of the largest flares in the cycle and 4 total X-class flares. No further M class flares would take place during the rest of Solar cycle 24.
2018
edit1
2
3
4
5
6
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
January
editA small active region, NOAA 12694, appeared at the surprisingly high latitude of S32, near the disk center (January 8). Its location conflicted directly with the expectation from the butterfly diagram. In principle new-cycle spots should appear at such a latitude, but this region had the correct polarity for Cycle 24.
March
editNOAA reported that the number of sunspots was the lowest since 2009, and that recent activity matched that of the low activity in 2007 and 2008. Should this prove to be the solar minimum, Solar Cycle 24 would uniquely become a short (10 year) and weak cycle. Sunspots were observed on only 5 days that month.[citation needed]
2019
edit2.5
5
7.5
10
12.5
15
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
May
editA C6.8 flare took place on 9 May 2019, the strongest solar flare to take place since October 2017.[96]
July
editNASA's Solar Dynamics Observatory recorded a sunspot from Solar Cycle 25. This sunspot is significant compared to previous sunspots from Solar Cycle 25 due to the fact that it lasted long enough to get a designation.[97]
October
editThe sun reached its absolute solar minimum in October 2019, marking the end of Solar cycle 24 and the beginning of Solar cycle 25.
See also
editReferences
edit- ^ Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2), 383-401.
- ^ "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
- ^ SIDC formula
- ^ National Weather Service. "Hello Solar Cycle 25". Retrieved 2020-09-15.
- ^ a b Dr. Tony Phillips (2008-01-10). "Solar Cycle 24 Begins". NASA. Retrieved 2010-05-29.
- ^ Dr. Tony Phillips (2010-06-04). "As the Sun Awakens, NASA Keeps a Wary Eye on Space Weather". NASA. Retrieved 2013-05-18.
- ^ "2014 : maximum year for solar cycle 24 | SILSO". www.sidc.be. Retrieved 2018-03-14.
- ^ Svalgaard, Leif (2005). "Sunspot cycle 24: Smallest cycle in 100 years?" (PDF). Geophysical Research Letters. 32 (1). doi:10.1029/2004GL021664. L01104.
- ^ Hathaway, David (December 21, 2006). "Scientists Predict Big Solar Cycle". NASA.
- ^ "Consensus Statement of the Solar Cycle 24 Prediction Panel". NOAA. Archived from the original on January 30, 2012.
- ^ "Solar Cycle Progression". National Oceanic and Atmospheric Administration. 8 May 2009.
- ^ "Climate Change Sanity". 9 January 2013.
- ^ Schatten, Kenneth (2005). "Fair space weather for solar cycle 24" (PDF). Geophysical Research Letters. 32 (21). GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L21106, doi:10.1029/2005GL024363. doi:10.1029/2005GL024363. Archived from the original (PDF) on 2016-01-21. Retrieved 2015-08-27.
- ^ "Solar Cycle Progression | NOAA NWS Space Weather Prediction Center". www.swpc.noaa.gov. Retrieved 2015-07-06.
- ^ "Giant Breach in Earth's Magnetic Field Discovered". NASA. 2008-12-16. Retrieved 2010-05-29.
- ^ Phillips, Tony (2010-06-14). "As the Sun Awakens, NASA Keeps a Wary Eye on Space Weather". Science@NASA. Retrieved 2010-06-15.
- ^ Thompson, Andrea (2008-12-16). "Leaks Found in Earth's Protective Magnetic Field". SPACE.com. Retrieved 2010-06-02.
As it orbited Earth, THEMIS's five spacecraft were able to estimate the thickness of the band of solar particles coming when the fields were aligned — it turned out to be about 20 times the number that got in when the fields were anti-aligned.
- ^ Kaku, Michio (2010-03-31). "A Possible Solar Storm in 2012?". Dr. Kaku's Universe. Big Think. Retrieved 2010-06-04.
Communication systems and power systems worldwide could be wiped out for months at a time. Something this large would cause not just a localized but rather a continent-wide power outage.
- ^ Clark, Stuart (2010-03-31). "What's wrong with the Sun?". New Scientist. No. 2764.
- ^ "Polar Field Reversal as observed with Hinode". NAOJ. 2012-04-19. Archived from the original on 2012-07-01. Retrieved 2012-06-21.
- ^ "12-21-2012 Just Another Day". NASA. 2012-07-03. Retrieved 2013-05-18.
- ^ "Beyond 2012: Why the World Didn't End". NASA. 2012-12-22. Retrieved 2013-05-18.
- ^ [1] Archived January 16, 2012, at the Wayback Machine
- ^ "Homepage - NOAA / NWS Space Weather Prediction Center". noaa.gov.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Solar Cycle 24 Prediction Updated May 2009 | NOAA / NWS Space Weather Prediction Center".
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Aurora Update". Harvard-Smithsonian Center for Astrophysics. 2010-08-03.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ Jones, Meg. "Northern lights produce great show Tuesday night; encore expected Wednesday". Milwaukee-Wisconsin Journal Sentinel. Retrieved 2010-08-04.
- ^ Kaplan, Jeremy (2010-08-04). "Solar Storm Causes Fantastic Light Show". Foxnews.com. Retrieved 2010-08-04.
- ^ "M5 solar flare". SpaceWeather.com.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ Valentine’s Day Solar Flare, NASA, February 17, 2011.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "Spaceweather.com Time Machine". spaceweather.com.
- ^ "Spaceweather.com Time Machine". spaceweather.com.
- ^ Sun packs a double punch, NASA website, August 4, 2011.
- ^ Strong geomagnetic storm in progress now as solar storm nails earth, WeatherSpace.com, August 5, 2011.
- ^ What's Up in Space, SpaceWeather.com, August 4, 2011.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "Spaceweather.com Time Machine". spaceweather.com.
- ^ "Strong solar activity continues". Southgate Amateur Radio News. 25 September 2011. Retrieved 25 September 2011.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "Spectacular Sun Diving Comet and M3.9 Class Flare – Oct 1, 2011". The Truth Behind the Scenes. Archived from the original on 2013-05-24. Retrieved 2012-03-10.
- ^ "Spaceweather.com Time Machine". spaceweather.com.
- ^ "Solar Flux - Climate Change Sanity". wordpress.com.
- ^ "SOLAR ACTIVITY PICKS UP". SpaceWeather. Retrieved 29 December 2011.
- ^ a b "Cycle 24 averages, by Solarham". Archived from the original on May 13, 2012. Retrieved 11 March 2012.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "NOAA GOES satellite image of largest solar radiation storm since 2005". Under the Mountain Bunker. Archived from the original on November 9, 2013. Retrieved 2012-01-24.
- ^ "Time Machine". Spaceweather.com. Retrieved 2012-01-24.
- ^ "Space Weather Alerts". Space Weather Prediction Center. NOAA. Archived from the original on 26 January 2012. Retrieved 27 January 2012.
- ^ "Spaceweather.com". Retrieved 27 January 2012.
- ^ "Space.com". 5 March 2012. Retrieved 5 March 2012.
- ^ "The Watchers". Retrieved 5 March 2012.
- ^ "Universe Today". 7 March 2012. Retrieved 7 March 2012.
- ^ "Space Weather Prediction Center's March 7th Report of Solar-Geophysical Activity". Archived from the original on 12 April 2010. Retrieved 7 March 2012.
- ^ "MASA". Retrieved 11 June 2012.
- ^ "This Months Solar Flare 'Likely Knocked' Military Satellites Offline". 23 March 2012. Retrieved 23 March 2012.
- ^ "Solar Storm Dumps Gigawatts into Earth's Upper Atmosphere". Retrieved 22 March 2012.
- ^ a b c "Big Blast--April 16th Flare and CME". NASA. 16 April 2012. Retrieved 2012-04-18.
- ^ "Huge Sunspot Aimed at Earth -- Eruption Imminent?: Big Pic". Discovery News. Retrieved 2012-05-11.
- ^ "Big Sunspot 1520 Releases X1.4 Class Flare". NASA. Retrieved 2012-07-14.
- ^ "AR1520's Parting Shot: July 19, 2012 M7.7 Flare". NASA. Retrieved 2012-07-21.
- ^ a b "August 31, 2012 Magnificent CME". NASA/Goddard Space Flight Center.
- ^ "Magnetic storms online, September 5, 2012". TESIS.
- ^ "The Sun Unleashes a Wide, but Benign, CME". NASA. September 30, 2012.
- ^ "G2 geomagnetic storm (Kp=6) again in progress". The Watchers.
- ^ a b c d e "Active Region on the Sun Emits Another Flare". NASA/Goddard Space Flight Center.
- ^ "Major eruption - Active region around east limb produced powerful X1.7 solar flare". The Watchers.
- ^ "M6.0 Flare". NASA Goddard Space Flight Center.
- ^ a b "Monthly Solar Flux and Sunspot Averages + Trend Charts". SolarHam.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Space Weather Alerts and Warnings Timeline, 1-15th April 2013". NOAA/Space Weather Prediction Center. Archived from the original on 2013-06-15.
- ^ "First X-Class Solar Flares of 2013". NASA/Goddard Space Flight Center. 13 May 2013.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ a b Tariq Malik, Monster solar flare: Why is the sun acting up now?, Christian Science Monitor, October 27, 2014.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Solar Dynamics Observatory Sees M7.9-Class Solar Flare". NASA/SDO. 25 June 2015.
- ^ "'Solar storm' grounds Swedish air traffic". The Local. 4 November 2015. Retrieved 4 November 2015.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "The first sunspot of cycle 25 is seen!". STCE. Retrieved 2016-12-22.
- ^ a b "News and information about meteor showers, solar flares, auroras, and near-Earth asteroids". SpaceWeather.com. 2020-01-08. Retrieved 2020-01-20.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Biggest solar flare in a decade causes radio blackout". cbsnews.com. Retrieved 2017-09-08.
- ^ "Giant Sunspot Unleashes 2 More Powerful Solar Flares". space.com. 7 September 2017. Retrieved 2017-09-08.
- ^ "The Last Best Flare of Cycle 24". Retrieved 2017-09-22.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Aurora and solar activity archive". spaceweatherlive. Retrieved 10 December 2020.
- ^ "Solar flares - Thursday, 9 May 2019". SpaceWeatherLive.com. Retrieved 14 October 2019.
- ^ "Spaceweather.com Time Machine". spaceweather.com. Retrieved 2019-07-12.