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Solar cycle 24

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Solar Cycle 24 is the 24th solar cycle since 1755, when recording of solar sunspot activity began.[1][2] It is the current solar cycle, and began on 8 January 2008.[3] Cycle continues to fall below predictions and is currently exhibiting 50% lower sunspot activity than predicted in May 2009.

ISES Solar Cycle Sunspot Number Progression as of May 2009

Predictions

It is predicted that Solar Cycle 24 will peak in May 2013 with 90 sunspots, which would be the fewest since solar cycle 16.[4]

ISES Solar Cycle Sunspot Number Progression as of Nov 2010

Currently the number of sunspots is approximately 50% below the latest predictions and if this trend continues, Solar Cycle 24 may represent the weakest cycle ever recorded.

The 2008 breach of Earth's magnetic shield

According to NASA, the intensity of geomagnetic storms during Solar Cycle 24 may be elevated in some area where the Earth's magnetic field is weaker than was expected, this result was discovered by the THEMIS spacecraft in 2008.[5][6][7][8] A 20-fold increase in particle counts that penetrate the Earth's magnetic field may be expected.[9]

Speculation

Solar Cycle 24 has been the subject of various hypotheses and commentary pertaining to its potential effects on Earth.

Without suggesting that the next solar maximum will be unusually destructive to Earth, astrophysicist Michio Kaku has taken 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 solar activity can inflict. He asserts that governments should ensure the integrity of electrical infrastructures, so as to prevent a recurrence of disruption akin to that caused by the solar storm of 1859.[10]

Solar Cycle 24 has also been cited by proponents of the 2012 phenomenon as evidence of a cataclysmic doomsday event aligned with their respective views.[citation needed]

The current solar cycle is currently the subject of research, as it does not appear to be generating sunspots in the manner which would be expected. Sunspots did not begin to appear immediately after the last minimum (in 2008) and although they started to reappear in late 2009, they are at significantly lower than anticipated.[11]

Events

August 2010

Coronal mass ejections

NASA Sunspot Number Predictions for Solar cycle 23 and 24

On August 1, 2010, scientists at the Harvard-Smithsonian Center for Astrophysics (CfA) observed a series of four large CMEs emanating from the Earth-facing hemisphere by analyzing images recorded at NASA's Solar Dynamics Observatory. The observed velocities of the ejecta varied between 670,560 m/s and 1,118,000 m/s (metre per second), and were expected to reach the Earth's geomagnetic field sometime between August 4 and early August 5. As of 05:00 UTC August 4, the estimated time of arrival of the series was as follows:

  • Wednesday, August 4 – 07:00 UTC
  • Wednesday, August 4 – 17:00 UTC
  • Thursday, August 5 – 00:00 UTC
  • Thursday, August 5 – 06:00 UTC[12]

All four ejections were described as large and, according to scientists, possessed enough energy to cause aurorae to be observed by naked eye in non-polar regions.[13] According to reports, aurorae would be visible at night toward the poleward horizon in temperate latitudes between 45° to 50°, and near overhead in regions closer to the poles.[14] The initial coronal mass ejection of August 1 originated from a sunspot designated Sunspot 1092, which was large enough to be seen without the aid of a solar telescope.[15] Aside from the visual effects of this CME series, scientists warned that electric impulses caused by disruptions in the magnetic field due to the ionized particles may damage infrastructure such as power grids and telephone lines not adequately protected against induced magnetic current. It has also been reported that several Earth-orbiting satellites may be in similar danger.[13] According to Leon Golub, an astronomer at CfA:

This eruption is directed right at us and is expected to get here early in the day on August 4. It's the first major Earth-directed eruption in quite some time. When such an expulsion reaches Earth, it interacts with the planet's magnetic field and can create a geomagnetic storm. Solar particles stream down the field lines toward Earth's poles. Those particles crash with atoms of nitrogen and oxygen in the atmosphere, which then glow like little neon signs. Sky watchers in the northern U.S. and other countries should look toward the north late Tuesday or early Wednesday for rippling "curtains" of green and red light.[16]

Aurorae observations

In the early morning hours of August 4, 2010 aurorae occurred in the northern hemisphere that were visible at latitudes as far south as Michigan and Wisconsin in the United States, and Ontario, Canada near latitude 45° North (see image at right). European observers reported sightings as far south as Denmark near latitude 56° North. 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.[17] This, however, was only the first wave of solar wind; the third and last was expected for the evening of August 5,[18] but missed Earth entirely.

  • Video captured by NASA's Solar Dynamics Observatory of the initial ejection taken August 1, 2010.
  • The coronal mass ejection starts at 2:36 UTC and ends at 3:56 UTC on August 1 in this animation on STEREO Ahead images.
  • Solar northern hemisphere during the first eruption as seen in extreme ultraviolet by the Solar Dynamics Observatory.
    Solar northern hemisphere during the first eruption as seen in extreme ultraviolet by the Solar Dynamics Observatory.
  • SDO multi-wavelength image of the August 1, 2010 event.
    SDO multi-wavelength image of the August 1, 2010 event.

See also

References

  1. ^ Kane, R.P. (2002). "Some Implications Using the Group Sunspot Number Reconstruction". Solar Physics 205(2), 383-401.
  2. ^ "The Sun: Did You Say the Sun Has Spots?". Space Today Online. Retrieved 12 August 2010.
  3. ^ "Solar Cycle 24 Begins". NASA. 2008-01-10. Retrieved 2010-05-29.
  4. ^ Huttner, Paul (2009-06-01). "New sunspot cycle may be lowest in 80 years". Minnesota Public Radio. Retrieved 2010-06-02. If the forecast is right, the new sunspot cycle will peak in May 2013 with a peak sunspot number of 90, the lowest since 1928 when Solar Cycle 16 peaked at 78.
  5. ^ "Giant Breach in Earth's Magnetic Field Discovered". NASA. 2008-12-16. Retrieved 2010-05-29.
  6. ^ Phillips, Tony (2010-06-14). "As the Sun Awakens, NASA Keeps a Wary Eye on Space Weather". Science@NASA. Retrieved 2010-06-15.
  7. ^ Hough, Andrew (2010-06-14). "Nasa warns solar flares from 'huge space storm' will cause devastation". The Telegraph. London. Retrieved 2010-06-15.
  8. ^ "NASA Warns of Potential "Huge Space Storm" In 2013". Slashdot. 2010-06-15. Retrieved 2010-06-15.
  9. ^ 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.
  10. ^ 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.
  11. ^ "What's wrong with the Sun?". New Scientist. 2010-03-31. {{cite news}}: |first= missing |last= (help)
  12. ^ "Aurora Update". Harvard-Smithsonian Center for Astrophysics. 2010-08-03.
  13. ^ a b "Solar Tsunami to Strike Earth Tonight". FoxNews.com. 2010-08-03.
  14. ^ "Alerte aux aurores boréales pour le 3 et le 4 août ! | Ciel et Espace" (in Template:Fr icon). Cieletespace.fr. Retrieved 2010-08-03.{{cite web}}: CS1 maint: unrecognized language (link)
  15. ^ "News and information about meteor showers, solar flares, auroras, and near-Earth asteroids". SpaceWeather.com. Retrieved 2010-08-03.
  16. ^ "Northern lights could illuminate the sky late Tuesday night". CNN.com. 2010-08-03.
  17. ^ Jones, Meg. "Northern lights produce great show Tuesday night; encore expected Wednesday". Milwaukee-Wisconsin Journal Sentinel. Retrieved 2010-08-04.
  18. ^ Kaplan, Jeremy (2010-08-04). "Solar Storm Causes Fantastic Light Show". Foxnews.com. Retrieved 2010-08-04.
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