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The Sun is the largest object in our solar system and essential to our survival
Indian scientists have reported the “first significant result” from Aditya-L1, the country's first solar observation mission in space.
On July 16, the most important of the seven scientific instruments that Aditya-L1 carried – the Visible Emission Line Coronagraph, or Velc – captured data that helped scientists estimate the precise time of the start of a mass ejection coronal (CME).
Studying CMEs – huge fireballs that erupt from the Sun's outermost coronal layer – is one of the most important scientific goals of India's first solar mission.
“Made of energetic particles, a CME could weigh up to a trillion kilograms and reach speeds of up to 3,000 km (1,864 miles) per second while traveling. It can head in any direction, including towards Earth,” says Professor R Ramesh of the Indian Institute of Astrophysics who designed Velc.
“Now imagine this huge ball of fire hurtling toward Earth. At its maximum speed, it would take about 15 hours to travel the 150 million kilometers distance from Earth to the Sun.
The coronal ejection captured by Velc on July 16 began at 1:08 p.m. GMT. Professor Ramesh, Velc's principal investigator who published a paper on this CME in the prestigious Astrophysical Journal Letters, said it came from the Earth side.
“But less than half an hour into its journey, it was diverted and took a different direction, placing itself behind the Sun. Since it was too far away, it had no impact on the weather on Earth.
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The solar corona is only visible during a total solar eclipse from Earth
But solar storms, solar flares and coronal mass ejections regularly impact Earth's climate. They also impact space weather where nearly 7,800 satellites are stationed, including more than 50 from India.
According to Space.com, they rarely pose a direct threat to human life, but they can cause chaos on Earth by interfering with Earth's magnetic field.
Their most benign impact causes magnificent auroras in locations near the North and South Poles. A stronger coronal mass ejection can cause auroras to appear in more distant skies, such as London or France – as was the case in May and October.
But the impact is much more serious in space where charged particles from a coronal mass ejection can cause a satellite's entire electronics to malfunction. They can destroy power grids and affect weather and communications satellites.
“Today, our lives are completely dependent on communication satellites and CMEs can disable the Internet, telephone lines and radio communications,” says Professor Ramesh. “This can lead to absolute chaos.”
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A coronal mass ejection can be several times larger than Earth
The most powerful solar storm in recorded history occurred in 1859. Called the Carrington Event, it triggered intense auroral light shows and destroyed telegraph lines across the world.
NASA scientists say a similarly violent storm was heading toward Earth in 2012 and we had “an equally perilous close shave.” They say a powerful coronal mass ejection tore apart Earth's orbit on July 23, but that we were “incredibly lucky” that instead of hitting our planet, the storm cloud hit the STEREO solar observatory -A from NASA in space.
In 1989, a coronal mass ejection knocked out part of Quebec's power grid for nine hours, leaving six million people without power.
And on November 4, 2015, solar activity disrupted air traffic control in Sweden and some other European airports, causing travel chaos for hours.
Scientists say that if we are able to see what is happening on the Sun, spot a solar storm or coronal mass ejection in real time and observe its trajectory, it can work as a warning to turn off power grids and satellites and keep them away. the danger.
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The Northern Lights lit up the UK night sky in October
The American space agency NASA, the European Space Agency (ESA), Japan and China have been observing the Sun through their space solar missions for decades. With Aditya-L1 – named after the Hindu Sun god – Indian space agency Isro joined this select group earlier this year.
From its vantage point in space, Aditya-L1 is capable of continuously observing the Sun, even during eclipses and occultations, and carrying out scientific studies.
Professor Ramesh says that when we look at the Sun from Earth, we see an orange fireball which is the photosphere – the surface of the Sun or the brightest part of the star.
Only during a total eclipse, when the Moon passes between the Earth and the Sun and covers the photosphere, can we see the solar corona, the outermost layer of the Sun.
According to Professor Ramesh, the Indian coronagraph has a slight advantage over the coronagraph of the NASA-ESA Joint Solar and Heliospheric Observatory.
“Ours is of such a size that it is able to mimic the role of the Moon and artificially hide the Sun's photosphere, thereby providing Aditya-L1 with an uninterrupted view of the corona 24 hours a day, 365 days per year.”
The NASA-ESA mission's coronagraph, he says, is larger, meaning it hides not only the photosphere but also parts of the corona – so it can't see the genesis of a CME if it comes from the hidden region.
“But with Velc, we can accurately estimate the time a coronal mass ejection begins and in which direction it is heading.”
India also has three ground-based observatories – at Kodaikanal, Gauribidanur in the south and Udaipur in the northwest – to observe the Sun. So, if we add their findings with those of Aditya-L1, we can greatly improve our understanding of the Sun, he adds.
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