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Por qué las auroras boreales pueden ser verdes, rojas o violetas: qué las desencadena y en qué épocas del año suelen aparecer con más frecuencia
Las auroras boreales son luces de colores que se forman en la atmósfera superior cerca del polo magnético norte y que, en determinadas noches, dibujan arcos, bandas y cortinas sobre el cielo oscuro. En el hemisferio sur el mismo fenómeno recibe el nombre de aurora austral. Aunque se las asocia con los paisajes del Ártico, su visibilidad depende de una cadena de condiciones que comienza en el Sol y termina a decenas o cientos de kilómetros sobre la superficie terrestre.
Según el Natural History Museum, la zona donde aparecen con mayor frecuencia es la franja auroral, un anillo de cerca de 3.000 kilómetros de diámetro que rodea el polo magnético norte. Por eso, Finlandia, Islandia y Canadá se encuentran entre los destinos con mayores posibilidades de observación. Sin embargo, cuando la actividad solar es intensa, esa región puede extenderse hacia latitudes más bajas y permitir avistamientos en lugares como el Reino Unido o el norte de Estados Unidos.
El verde suele ser el color predominante, pero las auroras también pueden adquirir tonos rojos, azules, violetas y rosados. Cada tonalidad depende del gas con el que interactúan las partículas cargadas y de la altitud a la que ocurre el choque. Para observarlas hacen falta, además, oscuridad, cielo despejado y poca contaminación lumínica.
Cómo se originan las auroras boreales
La NASA explica que una aurora comienza con el viento solar, una corriente de partículas que el Sol envía constantemente al espacio. Algunas de esas partículas tienen carga eléctrica, como ocurre con los electrones. Cuando llegan cerca de la Tierra, se encuentran con el campo magnético del planeta, una especie de escudo invisible que desvía la mayor parte de ellas. Gracias a esa protección, las partículas no llegan directamente a la atmósfera.
Sin embargo, parte de la energía que traen puede quedar almacenada alrededor de la Tierra. Luego, esa energía se libera y acelera algunas partículas hacia los polos norte y sur. Allí entran en las capas más altas de la atmósfera, donde chocan con gases como el oxígeno y el nitrógeno. Esas colisiones hacen que los gases emitan luz. De ese modo se forman los brillos verdes, rojos, violetas, azules y rosados que se ven en el cielo durante una aurora.
Las formas cambiantes del fenómeno, como arcos, franjas o cortinas, también están relacionadas con el campo magnético terrestre. Las partículas siguen sus recorridos invisibles hasta concentrarse en las zonas polares, por lo que las luces parecen moverse y ondularse en el cielo.
The Independent señala que, en ocasiones, el campo magnético de la Tierra libera de golpe parte de la energía que había acumulado. Ese cambio puede enviar más partículas hacia la atmósfera y volver la aurora más intensa.
Por eso, las auroras no se producen solamente porque partículas del Sol llegan a la Tierra. El campo magnético terrestre cumple una función decisiva: desvía la mayoría de esas partículas, almacena energía y guía una parte de ellas hacia los polos, donde finalmente se produce el espectáculo de luces.
El oxígeno y el nitrógeno explican la variedad de colores
La NASA indica que el color de una aurora depende de la composición de la atmósfera y de la altura a la que se produce la interacción. El oxígeno es responsable de los tonos verdes más frecuentes, que suelen aparecer entre los 100 y los 200 kilómetros de altitud. En esa región, la concentración de oxígeno y el tiempo que tardan sus átomos en liberar energía contribuyen a que el verde sea el tono más visible.
El mismo elemento puede emitir luz roja a mayor altura, por encima de los 200 kilómetros. Es un color menos habitual porque, en las capas más elevadas, hay menos oxígeno disponible para colisionar con las partículas energéticas. Por esa razón, el rojo suele asociarse con episodios de actividad solar más intensa, cuando aumenta la cantidad de partículas que alcanzan la atmósfera.
El nitrógeno, en cambio, interviene en los tonos azulados, violetas y rosados. Estos colores se forman en regiones cercanas a los 100 kilómetros de altitud o por debajo de ese nivel. Para llegar hasta allí, las partículas deben atravesar capas superiores sin perder toda su energía en choques previos con el oxígeno.
El amarillo puede aparecer cuando distintos colores se superponen a la vista. También existe emisión ultravioleta e infrarroja, aunque queda fuera del rango que el ojo humano puede detectar. Los instrumentos especializados permiten registrar parte de esa luz invisible y estudiar las auroras en otros mundos del sistema solar.
En efecto, el fenómeno no es exclusivo de la Tierra. Se han observado auroras en Marte, Júpiter y Saturno, así como en cometas y en estrellas distantes. Su presencia en distintos cuerpos celestes revela que la interacción entre partículas cargadas, gases y campos magnéticos puede producir espectáculos luminosos en ambientes muy diferentes.
Qué modifica el alcance e intensidad de las auroras
El Sol no siempre tiene la misma actividad. Pasa por ciclos de unos 11 años en los que su magnetismo se vuelve más o menos intenso. Durante las etapas de mayor actividad, llamadas máximo solar, se producen con más frecuencia grandes erupciones y nubes de gas con partículas cargadas que salen despedidas al espacio.
Si una de esas nubes llega a la Tierra, puede alterar el campo magnético que rodea al planeta. Según el Natural History Museum, esos cambios aumentan la posibilidad de que aparezcan auroras más fuertes y que puedan verse en lugares más alejados de los polos. Por eso, en momentos de actividad solar elevada, las luces pueden llegar a regiones situadas más al sur de lo habitual.
La época del año también influye. Las auroras suelen ser más frecuentes alrededor de los equinoccios, que ocurren entre marzo y abril y entre septiembre y octubre. En esos meses, la posición de la Tierra con respecto al Sol puede facilitar que más partículas lleguen a las zonas donde se forman las auroras.
Sin embargo, no es sencillo anticipar con exactitud cuándo aparecerán. Los especialistas observan la actividad del Sol y el comportamiento de las partículas que viajan por el espacio, pero los pronósticos son más fiables para las próximas horas que para varios días después. Además, una aurora puede estar presente y no ser visible desde un lugar determinado por las nubes o por la luz artificial.
Aurora,Aurora Boreal,Luces del Norte,cielo nocturno,naturaleza,paisaje,estrellas,Rovaniemi,Tromsø Municipality,fenómeno natural
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Most dramatic moments from Rep Mike Lawler’s fiery debate against Dem Cait Conley in battle for House control
Tensions flared on the debate stage Wednesday night, where Rep. Mike Lawler, R-N.Y., faced off against Democrat military veteran Cait Conley to represent their suburban New York district in Congress.
Lawler is vying for a third term representing the Empire State’s 17th Congressional District.
One of the few swing seats left in Congress, the race could prove decisive for which party controls the House of Representatives for the latter half of President Donald Trump’s term.
Below are some of the most dramatic moments during their one-hour head-to-head on PIX11 News:
HOW ONE NYC SUBURB COULD DECIDE WHICH PARTY CONTROLS THE HOUSE
While the debate was filled with the two political rivals criticizing each other, one tense moment came when Lawler turned his ire on moderator Dan Mannarino.
Mannarino had asked both Conley and Lawler what should be done to rein in Immigration and U.S. Customs Enforcement (ICE) agents who run afoul of their own guidelines, invoking the recent shooting of an illegal immigrant in the Bronx by federal officers while the man’s five-year-old was in the car.
Lawler pointed to the man’s rap sheet and accused Democrat state leaders of creating the situation with their sanctuary policies and Gov. Kathy Hochul’s recent bail reforms. He also accused Conley of supporting those policies.
The moderator began, «Mr. Lawler, I just want to follow up. The question was, how do you ensure if ICE agents do not follow through objectives, and what’s the discipline —»
«I understand the question,» Lawler said amid the cross-talk.
PROTESTS ERUPT IN THE BRONX AFTER ICE AGENT SHOOTS MAN DURING IMMIGRATION OPERATION
«But you didn’t answer the question,» Mannarino said.
«I understand the question. But here’s the problem, Danny,» Lawler shot back. «You guys want to focus on a gangbanger who has put people in harm’s way? I want to make sure that our communities are safe.»
ILLEGAL IMMIGRANT ACCUSED OF MURDERING COLLEGE STUDENT DIALS INTO HEARING FROM HOSPITAL BED
The GOP incumbent notably used the immigration standoff to pivot to the case of Sheridan Gorman, a teen from his district who was shot and killed near her college campus in Chicago earlier this year. The accused is an illegal immigrant who was previously arrested for shoplifting but was never turned over to ICE due to Chicago’s sanctuary policies.
Conley called Gorman’s death an «atrocious crime,» while Lawler repeatedly said over her, «It was preventable.»
SHERIDAN GORMAN’S MOM SCORCHES DEM LAWMAKERS SHE SAYS REFUSED TO HEAR FAMILIES OF SLAIN AMERICANS
«Can I finish?» an irate Conley shot back. «It was an atrocious crime committed in Chicago. And that man should have been deported. And I do support federal agents and federal law enforcement, federal immigration enforcement, making sure that we deport violent criminals.»
Lawler then pointed out, however, that the man would only have been deported if the sanctuary laws were not in place — laws he has repeatedly accused Conley of supporting along with her fellow Democrats.
«This is important,» Lawler began as the moderator tried to regain control. «If you think he should have been deported when he was arrested for shoplifting, he should have been turned over to ICE. Under the new law that you support, he will not be turned over to ICE and he will be released under cashless bail.»
«Mr. Lawler, there’s not a cross-examination round, so thank you,» the moderator said.
Conley quipped at her GOP rival, «If you wanted to be the moderator, you should have volunteered.»
At another point, the candidates were asked whether there should be a federal definition or law for consent to help stop sexual assault.
Conley took the moment to attack Lawler for being allied with Rep. Max Miller, R-Ohio, a fellow House Republican who has been accused of domestic violence by his wife. Miller has denied the allegations.
Lawler said their matter was «tragic’ and should be dealt with in family court without blaming either side. He then accused Conley of taking money from former New York Gov. Eliot Spitzer, who was revealed to be a client in a 2008 federal probe into a prostitution ring. Spitzer was never criminally prosecuted and resigned from his governorship amid the scandal.
«I’m sorry. I do not need — I do not need you to mansplain to me, domestic abuse and sexual assault against women,» Conley snapped. «Don’t start. I do not need you to mansplain to me, Mike.»
midterm elections, new york, house of representatives, congress, illegal immigrants, homeland security, politics
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Mamdani accuses Blakeman of ‘bigotry and racism’ in breakout debate that mayor didn’t watch
New York City Mayor Zohran Mamdani accused Republican gubernatorial candidate Bruce Blakeman of «bigotry and racism» Tuesday night despite admitting he didn’t watch Blakeman’s debate with Gov. Kathy Hochul live.
Mamdani made the statement in comments to reporters Wednesday after Blakeman and Hochul squared off Tuesday night. A reporter asked Mamdani whether he was bothered that Hochul hadn’t responded to Blakeman’s claims that the NYC mayor is an antisemite.
«So, I think, you know, it is hard for anyone to keep up with all of the bigotry and racism that Bruce Blakeman exhibits on a regular basis. So, I think that the governor did a good job. And I’ll never fault someone for not being able to catch all of it because that is a fool’s errand when it comes to Bruce Blakeman,» Mamdani said.
SHOCK POLL: POWERFUL BLUE STATE GOV’S LEAD SHRINKS TO SINGLE DIGITS WEEKS BEFORE ELECTION
«And I think the governor also made clear, you know, I’ve said that I, I didn’t watch the debate beyond the clip, but I think the governor has made clear time and time again what her vision is. It’s a vision of a more affordable New York,» he continued.
«And when it comes to Bruce Blakeman, his vision seems to be making life harder for working people. When the governor and I announced putting our city on a pathway to universal childcare, Bruce Blakeman went on television and said this was rewarding lazy parents who would sit at home and watch ‘The View.’ When we were speaking about concerns about what HR1 was going to do with regards to healthcare access across the state, Bruce Blakeman went on television and said that he would cut Medicaid in half.»
The debate opened with the candidates being asked about the conduct of U.S. Immigration and Customs Enforcement (ICE), which last week drew outrage in New York City after the shooting of a 28-year-old Dominican national whom the Department of Homeland Security said refused to comply with lawful orders during a targeted operation in the Bronx. A 5-year-old boy inside Oscar Bergal’s vehicle was unharmed.
«Kathy Hochul appealed to ICE to let this criminal out. The question that New Yorkers have to ask is what was this guy doing in New York in the first place? It’s because Kathy Hochul has made us a sanctuary state,» Blakeman said.
MAMDANI CALLS ICE A ‘ROGUE’ AGENCY AFTER NYC SHOOTING, CLAIMS AGENTS VIEW LAW AS ‘MERELY A SUGGESTION’
«Think about it. This guy came into the country illegally. He’s been convicted of a crime. He’s got pending charges for dealing drugs, poison to our children. And he’s a gang banger. This is who Kathy Hochul is defending?» Blakeman continued.
«I have a cooperative agreement with ICE until Kathy Hochul said we could no longer cooperate with ICE. We got over 2,000 illegal migrants out of my county with criminal records ranging from rape, attempted murder, robbery, burglary, drug dealing, carjacking, gang activity.
«And that’s because we cooperated with ICE, and we didn’t raid one school, one hospital, one daycare center or one church. If you cooperate with federal law enforcement, it makes for a safer community. That’s what I did. Kathy Hochul is taking that ability away from us. That’s why things like this happen.»
Hochul called Blakeman’s response a «non-answer» because «he refused to condemn what ICE did.»
MULLIN CALLS MAMDANI’S ANTI-ICE RHETORIC ‘DANGEROUS’ FOLLOWING NEW YORK SHOOTING
«So, he basically says in the state of New York, he’d be fine if ICE agents shoot into cars, shoot guns into vehicles, not knowing who’s inside and could have killed a 5-year-old child. If that doesn’t shock the conscience of everybody — and it should shock his conscience as well — that he says, ‘That’s OK, that’s how ICE is supposed to do it,’» Hochul added.
«I’ll tell you what. I oversee over 500 policing agencies in the state of New York. Over half a million arrests every year. That’s not how you conduct yourself. ICE is out of control. It’s out of control in Nassau County.»
Blakeman pushed back, saying, «It never would have happened» but for Hochul’s «sanctuary policy.»
Fox News’ Greg Norman contributed to this report.
zohran mamdani, kathy hochul, new york city, sanctuary cities, gubernatorial, new york, midterm elections
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El Salvador’s Bukele announces plan to free up to half of prisoners jailed in gang crackdown
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Salvadoran President Nayib Bukele has unveiled a plan that could allow the conditional early release of up to half of those detained under a state of emergency that authorities used to arrest more than 90,000 people in the past four and a half years as part of an effort to curb violent criminal gang activity.
Bukele’s plan to cut the prison population was announced on Tuesday night. It would focus on freeing prisoners who were deemed gang collaborators, a broad term that can include various people, including gang lookouts and those who make extortion payments.
«There are many people who have indeed committed crimes, but their crime was collaborating with gangs,» Bukele said. «They deserve to be in jail, but we come from a country where collaborating with gangs wasn’t so unusual, and if we were to arrest everyone who collaborated with gangs, we would have to arrest 20% of the population.»
Without offering details, the president indicated that authorities plan to analyze cases to determine potential early release with monitoring, which could apply to half of the people detained during the state of emergency.
TRUMP ADMINISTRATION SAYS FEDERAL AUTHORITIES HAVE ARRESTED MORE THAN 10,000 SUSPECTED GANG MEMBERS
Salvadoran President Nayib Bukele has unveiled a plan that could allow the conditional early release of up to half of those detained under a state of emergency. (Alex Peña/Getty Images)
The state of emergency was declared in March 2022 after a surge in violence left more than 60 people dead in a single day. The measure was initially imposed for 30 days but has been repeatedly extended.
The emergency declaration has coincided with a dramatic decline in the country’s homicide rate and helped make El Salvador a more appealing tourist destination while also suspending or restricting certain constitutional protections, including the right to be informed of the reasons for detention, the right to access legal counsel and the right to visitation.
El Salvador’s president has maintained that the measure was needed to rein in rival gangs MS-13 and Barrio 18.
Human rights groups, meanwhile, have denounced the declared emergency, arguing that it has sparked widespread arbitrary arrests. The groups have repeatedly demanded that Bukele scrap the measure.
NICOLAS MADURO AND WIFE CILIA FLORES FACE NEW CHARGE OF CONSPIRACY TO TORTURE AMERICANS
El Salvador President Nayib Bukele’s emergency declaration suspended or restricted certain constitutional protections, including the right to be informed of the reasons for detention, the right to access legal counsel and the right to visitation. (Alex Pena/Anadolu via Getty Images)
Human rights organizations have recorded more than 6,000 complaints during the emergency declaration and documented the deaths of at least 575 people in government custody.
The potential release of thousands of prisoners, some argue, is not enough to repair the damage of their prolonged imprisonment.
«The victims of arbitrary detentions don’t just deserve to recover their freedom, but they also deserve to be compensated for the harms caused by the State of El Salvador: the physical and mental harm that imprisonment causes, family suffering, loss of work or studies, reputational damage, among others,» exiled Salvadoran lawyer Bertha Deleón wrote on X.
Bukele dismissed widespread criticism from national and international human rights groups, suggesting that they should take the side of the victims of gang violence.
Human rights groups have denounced the state of emergency, arguing that it has sparked widespread arbitrary arrests. (Salvadoran Government via Getty Images)
The president also defended the need to keep the state of emergency while also indicating his goal of ending it eventually.
El Salvador’s homicide rate has fallen dramatically over the past decade, including during Bukele’s presidency, according to government figures. The rate dropped from a peak of more than 100 murders per 100,000 residents in 2015, four years before Bukele took office, to 1.3 per 100,000 in 2025.
But the government has narrowed the definition of homicide to exclude killings by police, murders in prisons and bodies found in unmarked graves.
The Associated Press contributed to this report.
world, human rights, ms 13, latin america, latino, central america
Most dramatic moments from Rep Mike Lawler’s fiery debate against Dem Cait Conley in battle for House control
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