For broader coverage of this topic, see Solar cycle.
Solar minimum is the regular period of least solar activity in the Sun's 11-year solar cycle. During solar minimum, sunspot and solar flare activity diminishes, and often does not occur for days at a time. On average, the solar cycle takes about 11 years to go from one solar minimum to the next, with duration observed varying from 9 to 14 years. The date of the minimum is described by a smoothed average over 12 months of sunspot activity, so identifying the date of the solar minimum usually can only happen 6 months after the minimum takes place.
Three recent solar cycles
Solar minimum is contrasted with the solar maximum, when hundreds of sunspots may occur.
Solar minima and maxima are the two extremes of the Sun's 11-year and 400-year activity cycle.[1] At a maximum, the Sun is peppered with sunspots, solar flares erupt, and the Sun hurls billion-ton clouds of electrified gas into space. Sky watchers may see more auroras, and space agencies must monitor radiation storms for astronaut protection. Power outages, satellite malfunctions, communication disruptions, and GPS receiver malfunctions are just a few of the things that can happen during a solar maximum.[2]
At a solar minimum, there are fewer sunspots and solar flares subside. Sometimes, days or weeks go by without a spot.
Predicting solar minimum cyclesEdit
Their non-linear character makes predictions of solar activity very difficult.[3] The solar minimum is characterized by a period of decreased solar activity with few, if any, sunspots. Scientists from the National Center for Atmospheric Research (NCAR) also developed a computer model of solar dynamics (Solar dynamo) for more accurate predictions and have confidence in the forecast based upon a series of test runs with the newly developed model simulating the strength of the past eight solar cycles with more than 98% accuracy.[4] In hindsight the prediction proved to be wildly inaccurate and not representative of the observed sunspot numbers.[5]
During 2008–09 NASA scientists noted that the Sun is undergoing a "deep solar minimum," stating: "There were no sunspots observed on 266 of [2008's] 366 days (73%). Prompted by these numbers, some observers suggested that the solar cycle had hit bottom in 2008. Sunspot counts for 2009 dropped even lower. As of September 14, 2009 there were no sunspots on 206 of the year's 257 days (80%). Solar physicist Dean Pesnell of the Goddard Space Flight Center came to the following conclusion: "We're experiencing a very deep solar minimum." His statement was confirmed by other specialists in the field. "This is the quietest sun we've seen in almost a century," agreed sunspot expert David Hathaway of the National Space Science and Technology Center NASA/Marshall Space Flight Center.[6] However, the activity is still at a higher level than at a grand solar minimum.
Grand solar minima occur when several solar cycles exhibit lesser than average activity for decades or centuries. Solar cycles still occur during these grand solar minimum periods but are at a lower intensity than usual. The grand minima form a special mode of the solar dynamo operation.[7]
A list of historical Grand minima of solar activity[9] includes also Grand minima ca. 690 AD, 360 BC, 770 BC, 1390 BC, 2860 BC, 3340 BC, 3500 BC, 3630 BC, 3940 BC, 4230 BC, 4330 BC, 5260 BC, 5460 BC, 5620 BC, 5710 BC, 5990 BC, 6220 BC, 6400 BC, 7040 BC, 7310 BC, 7520 BC, 8220 BC, 9170 BC.
^Moussas, X.; Polygiannakis, J. M.; Preka-Papadema, P.; Exarhos, G. (2005). "Solar cycles: A tutorial". Advances in Space Research. 35 (5): 725–738. Bibcode:2005AdSpR..35..725M. doi:10.1016/j.asr.2005.03.148.
^"NOAA Space Weather Scales Page Has Changed". noaa.gov.
^Petrovay, Kristof (2010). "Solar Cycle Prediction". Living Reviews in Solar Physics. 7 (1): 6. arXiv:1012.5513. Bibcode:2010LRSP....7....6P. doi:10.12942/lrsp-2010-6. PMC4841181. PMID 27194963.
^. ucar.edu. Archived from the original on 2006-04-10.
^. nasa.gov. Archived from the original on 2009-04-01.
^C.-J. Wu; I. G. Usoskin; N. Krivova; G.A. Kovaltsov; M. Baroni; E. Bard; S.K. Solanki (2018). "Solar activity over nine millennia: A consistent multi-proxy reconstruction". Astronomy and Astrophysics. 615: A93. arXiv:1804.01302. Bibcode:2018A&A...615A..93W. doi:10.1051/0004-6361/201731892. S2CID 119376474.
^Celia Martin-Puertas; Katja Matthes; Achim Brauer; Raimund Muscheler; Felicitas Hansen; et al. (April 2, 2012). "Regional atmospheric circulation shifts induced by a grand solar minimum". Nature Geoscience. 5 (6): 397–401. Bibcode:2012NatGe...5..397M. doi:10.1038/ngeo1460.
^Usoskin, Ilya G.; Solanki, Sami K.; Kovaltsov, Gennady A. (2007). "Grand minima and maxima of solar activity: new observational constraints" (PDF). Astron. Astrophys. 471 (1): 301–9. arXiv:0706.0385. Bibcode:2007A&A...471..301U. doi:10.1051/0004-6361:20077704. S2CID 7742132.
External linksEdit
New Insights on How Solar Minimums Affect Earth (NASA June 14, 2011)
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For broader coverage of this topic see Solar cycle Solar minimum is the regular period of least solar activity in the Sun s 11 year solar cycle During solar minimum sunspot and solar flare activity diminishes and often does not occur for days at a time On average the solar cycle takes about 11 years to go from one solar minimum to the next with duration observed varying from 9 to 14 years The date of the minimum is described by a smoothed average over 12 months of sunspot activity so identifying the date of the solar minimum usually can only happen 6 months after the minimum takes place Three recent solar cyclesSolar minimum is contrasted with the solar maximum when hundreds of sunspots may occur Contents 1 Solar minimum and solar maximum 2 Predicting solar minimum cycles 3 Grand solar minima and maxima 4 See also 5 References 6 External linksSolar minimum and solar maximum EditSolar minima and maxima are the two extremes of the Sun s 11 year and 400 year activity cycle 1 At a maximum the Sun is peppered with sunspots solar flares erupt and the Sun hurls billion ton clouds of electrified gas into space Sky watchers may see more auroras and space agencies must monitor radiation storms for astronaut protection Power outages satellite malfunctions communication disruptions and GPS receiver malfunctions are just a few of the things that can happen during a solar maximum 2 At a solar minimum there are fewer sunspots and solar flares subside Sometimes days or weeks go by without a spot Predicting solar minimum cycles EditTheir non linear character makes predictions of solar activity very difficult 3 The solar minimum is characterized by a period of decreased solar activity with few if any sunspots Scientists from the National Center for Atmospheric Research NCAR also developed a computer model of solar dynamics Solar dynamo for more accurate predictions and have confidence in the forecast based upon a series of test runs with the newly developed model simulating the strength of the past eight solar cycles with more than 98 accuracy 4 In hindsight the prediction proved to be wildly inaccurate and not representative of the observed sunspot numbers 5 During 2008 09 NASA scientists noted that the Sun is undergoing a deep solar minimum stating There were no sunspots observed on 266 of 2008 s 366 days 73 Prompted by these numbers some observers suggested that the solar cycle had hit bottom in 2008 Sunspot counts for 2009 dropped even lower As of September 14 2009 there were no sunspots on 206 of the year s 257 days 80 Solar physicist Dean Pesnell of the Goddard Space Flight Center came to the following conclusion We re experiencing a very deep solar minimum His statement was confirmed by other specialists in the field This is the quietest sun we ve seen in almost a century agreed sunspot expert David Hathaway of the National Space Science and Technology Center NASA Marshall Space Flight Center 6 However the activity is still at a higher level than at a grand solar minimum Grand solar minima and maxima EditMain article Solar cycle Grand solar minima occur when several solar cycles exhibit lesser than average activity for decades or centuries Solar cycles still occur during these grand solar minimum periods but are at a lower intensity than usual The grand minima form a special mode of the solar dynamo operation 7 nbsp 400 year history of sunspot numbers Solar minimum and maximum events with approximate dates Event Start EndHomeric Minimum 8 950 BC 800 BCRoman Warm Period 250 BC AD 400Medieval maximum 1 see Medieval Warm Period 950 1040Oort minimum see Medieval Warm Period 1040 1080Medieval maximum 2 see Medieval Warm Period 1100 1250Wolf minimum 1280 1350Sporer Minimum 1450 1550Maunder Minimum 1645 1715Dalton Minimum 1790 1820Modern Maximum 1914 2008A list of historical Grand minima of solar activity 9 includes also Grand minima ca 690 AD 360 BC 770 BC 1390 BC 2860 BC 3340 BC 3500 BC 3630 BC 3940 BC 4230 BC 4330 BC 5260 BC 5460 BC 5620 BC 5710 BC 5990 BC 6220 BC 6400 BC 7040 BC 7310 BC 7520 BC 8220 BC 9170 BC See also EditActive region List of solar cycles Maunder Minimum Solar cycle Solar cycle 24 Solar maximumReferences Edit Moussas X Polygiannakis J M Preka Papadema P Exarhos G 2005 Solar cycles A tutorial Advances in Space Research 35 5 725 738 Bibcode 2005AdSpR 35 725M doi 10 1016 j asr 2005 03 148 NOAA Space Weather Scales Page Has Changed noaa gov Petrovay Kristof 2010 Solar Cycle Prediction Living Reviews in Solar Physics 7 1 6 arXiv 1012 5513 Bibcode 2010LRSP 7 6P doi 10 12942 lrsp 2010 6 PMC 4841181 PMID 27194963 Scientists Issue Unprecedented Forecast of Next Sunspot Cycle News Release ucar edu Archived from the original on 2006 04 10 Sunspot Number graphics oma be Deep Solar Minimum NASA Science nasa gov Archived from the original on 2009 04 01 C J Wu I G Usoskin N Krivova G A Kovaltsov M Baroni E Bard S K Solanki 2018 Solar activity over nine millennia A consistent multi proxy reconstruction Astronomy and Astrophysics 615 A93 arXiv 1804 01302 Bibcode 2018A amp A 615A 93W doi 10 1051 0004 6361 201731892 S2CID 119376474 Celia Martin Puertas Katja Matthes Achim Brauer Raimund Muscheler Felicitas Hansen et al April 2 2012 Regional atmospheric circulation shifts induced by a grand solar minimum Nature Geoscience 5 6 397 401 Bibcode 2012NatGe 5 397M doi 10 1038 ngeo1460 Usoskin Ilya G Solanki Sami K Kovaltsov Gennady A 2007 Grand minima and maxima of solar activity new observational constraints PDF Astron Astrophys 471 1 301 9 arXiv 0706 0385 Bibcode 2007A amp A 471 301U doi 10 1051 0004 6361 20077704 S2CID 7742132 External links EditSolar Cycle 25 peaking around 2022 could be one of the weakest in centuries New Insights on How Solar Minimums Affect Earth NASA June 14 2011 Portals nbsp Astronomy nbsp Stars nbsp Spaceflight nbsp Outer space nbsp Solar System Retrieved from https en wikipedia org w index php title Solar minimum amp oldid 1112437628, wikipedia, wiki, book, books, library,
