New Delhi:

Auroras illuminated the skies across many regions on Saturday. This was the second time in a row on May 11 that auroras lit up the skies across swaths of the planet.

This spectacular celestial show, which is usually confined to the far northern reaches of the planet and is called “northern lights”, is triggered by a powerful solar storm.

A report by news agency AFP stated that this powerful solar storm could also continue on Sunday.

Why do we get auroras?

The National Aeronautics and Space Administration (NASA), on Sunday, shared a thread on X (formerly Twitter) explaining the phenomenon.

Why do we get auroras on Earth after eruptions occur on the Sun? A thread. ????

(Images:
Left: a solar flare captured by NASA’s Solar Dynamics Observatory.
Right: Aurora seen from Lummi Island, Washington, at 10:54 p.m. PT on May 10, 2024. Credit: Jeff Carter) pic.twitter.com/0seln79n0p

— NASA Sun & Space (@NASASun) May 11, 2024

NASA explained the two things that they call solar eruptions—solar flares and coronal mass ejections (CMEs).

NASA wrote, “There are two things we call solar eruptions: solar flares and coronal mass ejections (CMEs). They often occur together, but not always. Solar flares are intense flashes of light — a result of the Sun’s complex magnetic fields abruptly rearranging themselves.”

There are two things we call solar eruptions: solar flares and coronal mass ejections (CMEs). They often occur together, but not always.

Solar flares are intense flashes of light — a result of the Sun’s complex magnetic fields abruptly rearranging themselves. pic.twitter.com/s6qYXQIkw8

— NASA Sun & Space (@NASASun) May 11, 2024

Talking about CMEs, it added, “Coronal mass ejections (CMEs) are giant clouds of solar particles laced with magnetic fields that escape from the Sun. These giant clouds can travel anywhere in the solar system, including to us here on Earth.”

Coronal mass ejections (CMEs) are giant clouds of solar particles laced with magnetic fields that escape from the Sun. These giant clouds can travel anywhere in the solar system, including to us here on Earth. pic.twitter.com/HiuoTtSe3W

— NASA Sun & Space (@NASASun) May 11, 2024

NASA said that because solar flares are light, they reach Earth in about 8 minutes, while CMEs can take days to reach us. However, when they do they can set the aurora light.

“Solar flares reach us quickly — light only takes about 8 minutes to reach Earth. Because CMEs are made up of particles, they may take days to reach us. But when they do, they can set the aurora alight,” added NASA.

Solar flares reach us quickly — light only takes about 8 minutes to reach Earth.

Because CMEs are made up of particles, they may take days to reach us.

But when they do, they can set the aurora alight. pic.twitter.com/0L0WDJmwWy

— NASA Sun & Space (@NASASun) May 11, 2024

In addition, when these CMEs collide with Earth’s magnetic field, they dump “solar particles into near-earth space.” Now, these particles dive into earth’s atmosphere in a ring “around the poles, called auroral oval.”

“When a CME collides with Earth’s magnetic field, it can dump solar particles into near-Earth space. These particles follow Earth’s magnetic field lines as they dive into our atmosphere in a “ring” around the poles called the auroral oval,” NASA wrote.

When a CME collides with Earth’s magnetic field, it can dump solar particles into near-Earth space.

These particles follow Earth’s magnetic field lines as they dive into our atmosphere in a “ring” around the poles called the auroral oval. pic.twitter.com/xT4U7SG3Tq

— NASA Sun & Space (@NASASun) May 11, 2024

After these incoming particles strike gases, present in Earth’s atmosphere, it heats up and starts glowing. NASA stated, “The incoming particles strike gases in our atmosphere, causing them to heat up and glow: the aurora. The colours depend on the type of gas and its altitude. Oxygen glows red or blue; nitrogen can be green, blue, or pink.”

The incoming particles strike gases in our atmosphere, causing them to heat up and glow: the aurora.

The colors depend on the type of gas and its altitude. Oxygen glows red or blue; nitrogen can be green, blue, or pink.

Image Credit: NASA/Aurorasaurus pic.twitter.com/9uqicvBPSl

— NASA Sun & Space (@NASASun) May 11, 2024

Sharing a glimpse of last night’s northern lights reported in the Bahamas, NASA wrote, “Powerful, repeated eruptions like those we’ve had recently can widen the auroral oval, pushing aurora to lower latitudes. Last night, northern lights were reported as far south as the Bahamas!”

Powerful, repeated eruptions like those we’ve had recently can widen the auroral oval, pushing aurora to lower latitudes. Last night, northern lights were reported as far south as the Bahamas!

Here’s last night’s view from Bear Lake, Utah. Credit: NASA/Bill Dunford pic.twitter.com/E5BnrvqqpP

— NASA Sun & Space (@NASASun) May 11, 2024

Meanwhile, from northern Europe to Australia’s Tasmania, the sky-gazers last night witnessed stunning auroras that painted the skies in pink, green, and purple.

The sun as seen by the Solar Orbiter spacecraft in extreme ultraviolet light in this mosaic of 25 individual images taken on March 7, 2023, by the high-resolution telescope of the Extreme Ultraviolet Imager (EUI) instrument. Taken at a wavelength of 17 nanometers, in the extreme ultraviolet region of the electromagnetic spectrum, this image reveals the sun’s upper atmosphere, the corona.
| Photo Credit: Reuters

The solar wind is a ubiquitous feature of our solar system. This relentless high-speed flow of charged particles from the sun fills interplanetary space. On Earth, it triggers geomagnetic storms that can disrupt satellites and it causes the dazzling auroras – the northern and southern lights – at high latitudes.

But precisely how the sun generates the solar wind has remained unclear. New observations by the Solar Orbiter spacecraft may provide an answer.

Researchers on Thursday said the spacecraft has detected numerous relatively small jets of charged particles expelled intermittently from the corona – the sun’s outer atmosphere – at supersonic speeds for 20 to 100 seconds.

The jets emanate from structures on the corona called coronal holes where the sun’s magnetic field stretches into space rather than back into the star. They are called “picoflare jets” due to their relatively small size. They arise from areas a few hundred miles wide – tiny when compared to the immense scale of the sun, which has a diameter of 865,000 miles (1.4 million km).

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“We suggest that these jets could actually be a major source of mass and energy to sustain the solar wind,” said solar physicist Lakshmi Pradeep Chitta of the Max Planck Institute for Solar System Research in Germany, lead author of the research published in the journal Science.

The solar wind consists of plasma – ionized gas, or gas in which the atoms lose their electrons – and is mostly ionized hydrogen.

“Unlike the wind on Earth that circulates the globe, solar wind is ejected outward into interplanetary space,” Chitta said.

“Earth and the other planets in the solar system whiz through the solar wind as they orbit around the sun. Earth’s magnetic field and atmosphere act as shields and protects life by blocking harmful particles and radiation from the sun. But the solar wind continuously propagates outward from the sun and inflates a plasma bubble called the heliosphere that encompasses the planets,” Chitta added.

The heliosphere extends out to about 100 to 120 times further than Earth’s distance to the sun.

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The data for the study was obtained last year by one of the three telescopes on an instrument called the Extreme Ultraviolet Imager aboard the Solar Orbiter, a sun-observing probe built by the European Space Agency and the U.S. space agency NASA that was launched in 2020. The Solar Orbiter was about 31 million miles (50 million km) from the sun at the time – about a third of the distance separating the sun and Earth.

“This finding is important as it sheds more light on the physical mechanism of the solar wind generation,” said solar physicist and study co-author Andrei Zhukov of the Royal Observatory of Belgium.

The solar wind’s existence was predicted by American physicist Eugene Parker in the 1950s and was verified in the 1960s.

“Still, the origin of the solar wind remains a longstanding puzzle in astrophysics,” Chitta said. “A key challenge is to identify the dominant physical process that powers the solar wind.”

The Solar Orbiter is discovering new details about the solar wind and is expected to obtain even better data in the coming years using additional instruments and viewing the sun from other angles.

Zhukov said stellar wind is a phenomenon common to most, if not all, stars, though the physical mechanism may differ among various types of stars.

“Our understanding of the sun is much more detailed than the understanding of other stars, due to its proximity and thus the possibility to make more detailed observations,” Zhukov added.