NOTÍCIAS
12/09/2014 20:05 -03 | Atualizado 26/01/2017 22:12 -02

Dupla tempestade solar ruma à Terra e preocupa cientistas

www.flickr.com/photos/gsfc/6961978265The sun erupted with one of the largest solar flares of this solar cycle on March 6, 2012 at 7PM ET. This flare was categorized as an X5.4, making it the second largest flare -- after an X6.9 on August 9, 2011 -- since the sun’s activity segued into a period of relatively low activity called solar minimum in early 2007. The current increase in the number of X-class flares is part of the sun’s normal 11-year solar cycle, during which activity on the sun ramps up to solar maximum, which is expected to peak in late 2013.About an hour later, at 8:14 PM ET, March 6, the same region let loose an X1.3 class flare. An X1 is 5 times smaller than an X5 flare.These X-class flares erupted from an active region named AR 1429 that rotated into view on March 2. Prior to this, the region had already produced numerous M-class and one X-class flare. The region continues to rotate across the front of the sun, so the March 6 flare was more Earthward facing than the previous ones. It triggered a temporary radio blackout on the sunlit side of Earth that interfered with radio navigation and short wave radio.In association with these flares, the sun also expelled two significant coronal mass ejections (CMEs), which are travelling faster than 600 miles a second and may arrive at Earth in the next few days. In the meantime, the CME associated with the X-class flare from March 4 has dumped solar particles and magnetic fields into Earth’s atmosphere and distorted Earth's magnetic fields, causing a moderate geomagnetic storm, rated a G2 on a scale from G1 to G5. Such storms happen when the magnetic fields around Earth rapidly change strength and shape. A moderate storm usually causes aurora and may interfere with high frequency radio transmission near the poles. This storm is already dwindling, but the Earth may experience another enhancement if the most recent CMEs are directed toward and impact Earth.In addition, last night’s flares have sent solar particles into Earth’s atmosphere, producing a moderate solar energetic particle event, also called a solar radiation storm. These particles have been detected by NASA’s SOHO and STEREO spacecraft, and NOAA’s GOES spacecraft. At the time of writing, this storm is rated an S3 on a scale that goes up to S5. Such storms can interfere with high frequency radio communication.Besides the August 2011 X-class flare, the last time the sun sent out flares of this magnitude was in 2006. There was an X6.5 on December 6, 2006 and an X9.0 on December 5, 2006. Like the most recent events, those two flares erupted from the same region on the sun, which is a common occurrence. Credit: NASA/SDO/AIA NASA image use policy.NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.Follow us on TwitterLike us on FacebookFind us on Instagram" data-caption="NASA image captured March 6, 2012To view a still image from this event go to: www.flickr.com/photos/gsfc/6961978265The sun erupted with one of the largest solar flares of this solar cycle on March 6, 2012 at 7PM ET. This flare was categorized as an X5.4, making it the second largest flare -- after an X6.9 on August 9, 2011 -- since the sun’s activity segued into a period of relatively low activity called solar minimum in early 2007. The current increase in the number of X-class flares is part of the sun’s normal 11-year solar cycle, during which activity on the sun ramps up to solar maximum, which is expected to peak in late 2013.About an hour later, at 8:14 PM ET, March 6, the same region let loose an X1.3 class flare. An X1 is 5 times smaller than an X5 flare.These X-class flares erupted from an active region named AR 1429 that rotated into view on March 2. Prior to this, the region had already produced numerous M-class and one X-class flare. The region continues to rotate across the front of the sun, so the March 6 flare was more Earthward facing than the previous ones. It triggered a temporary radio blackout on the sunlit side of Earth that interfered with radio navigation and short wave radio.In association with these flares, the sun also expelled two significant coronal mass ejections (CMEs), which are travelling faster than 600 miles a second and may arrive at Earth in the next few days. In the meantime, the CME associated with the X-class flare from March 4 has dumped solar particles and magnetic fields into Earth’s atmosphere and distorted Earth's magnetic fields, causing a moderate geomagnetic storm, rated a G2 on a scale from G1 to G5. Such storms happen when the magnetic fields around Earth rapidly change strength and shape. A moderate storm usually causes aurora and may interfere with high frequency radio transmission near the poles. This storm is already dwindling, but the Earth may experience another enhancement if the most recent CMEs are directed toward and impact Earth.In addition, last night’s flares have sent solar particles into Earth’s atmosphere, producing a moderate solar energetic particle event, also called a solar radiation storm. These particles have been detected by NASA’s SOHO and STEREO spacecraft, and NOAA’s GOES spacecraft. At the time of writing, this storm is rated an S3 on a scale that goes up to S5. Such storms can interfere with high frequency radio communication.Besides the August 2011 X-class flare, the last time the sun sent out flares of this magnitude was in 2006. There was an X6.5 on December 6, 2006 and an X9.0 on December 5, 2006. Like the most recent events, those two flares erupted from the same region on the sun, which is a common occurrence. Credit: NASA/SDO/AIA NASA image use policy.NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.Follow us on TwitterLike us on FacebookFind us on Instagram" data-credit="NASA Goddard Photo and Video/Flickr">

Uma rara explosão dupla de tempestades solares magneticamente carregadas vai atingir a Terra nesta sexta-feira, causando preocupações de que sinais GPS, comunicações por rádio e transmissões de energia possam ser interrompidos, disseram autoridades nesta quinta.

Individualmente, as tempestades, conhecidas como ejeções de massa coronal, ou CMEs, não justificariam advertências especiais, mas o curto intervalo atípico e sua rota direta para a Terra levaram o Centro de Previsão Climática dos Estados Unidos (SWPC) a emitir um alerta.

Dado ao nível de intensidade geomagnética esperado, essas tempestades "poderão provocar problemas nas comunicações por rádio e sinal de GPS, assim como irregularidades na voltagem da rede de distribuição elétrica", disse Thomas Berger, diretor do centro.

Os efeitos seriam mais sentidos nas regiões próximas aos polos, onde as interações com o campo magnético terrestre são mais fortes. "Nós não esperamos nenhum impacto incontornável à infraestrutura nacional, mas estamos acompanhando de perto", acrescentou Berger.

O Sol está atualmente no pico de seu ciclo de 11 anos, embora o nível de atividade esteja menor do que o típico para um pico solar. Tempestades como as que agora rumam para a Terra ocorrem entre 100 e 200 vezes durante um ciclo solar de 11 anos, explicou Berger.

Para o cientista, a imprevisibilidade da dupla explosão solar exige uma maior preocupação. "O fato único sobre este evento é que nós tivemos dois em rápida sucessão e as CMEs poderiam estar interagindo em seu caminho para a Terra, na órbita da Terra ou além.

"Nós simplesmente não sabemos ainda", disse ele. O SWPC estima que os efeitos das tempestades ainda serão sentidos no planeta no sábado.

No lado positivo, os eventos solares devem provocar belas auroras nas regiões polares, incluindo o norte dos Estados Unidos e do Canadá.

Histórico

Em 2012, uma forte tempestade solar quase atingiu a Terra, colocando em sério risco todo o sistema de redes elétricas e ameaçando "reenviar a civilização contemporânea ao século XVIII", revelou a Nasa em julho.

A agência espacial americana estima que o impacto de uma tempestade solar como a de 1859 – conhecida como "evento Carrington" – custaria à economia mundial dois trilhões de dólares e provocaria danos sem precedentes em um mundo inteiramente dependente da eletricidade e da eletrônica.

via: