Aviation

Blast! The Sun’s at it again. Solar flares are commonplace, but the… | by unexpected-patronus | Nakshatra, NIT Trichy | Apr, 2022

Some things are universal experiences. A website taking too long to load. A watched pot, refusing to boil. And to top it off, your phone’s plugged in, but you forgot to turn on the charger and now it’s in danger of imminent death. It’s the last straw, right before something goes snap! To err, or maybe to erupt, is human, and we’ve seen our tempers light on fire when we’re stressed out. But did you know that the Sun flares up, too?

Yup, our friendly neighbourhood star has its bad days, and unlike humans, its outbursts are intense and powerful eruptions of energy that travel several millions of kilometres, all the way into the Solar System. Some of these flares impact life on earth quite significantly too. Why does that happen?

Our Sun has an 11-year cycle of magnetic activity, and phenomena like sunspots and solar flares happen when this activity is at its peak. Solar flares occur when the plasma in the Sun accelerates particles like electrons, protons and other heavier ions. When accelerated to near-light speeds, these particles produce vast amounts of radiation and violently erupt, moving outwards to the rest of the Solar system. That’s why solar flares are also termed coronal mass ejections (CME). Incidentally, CMEs are also what give us space weather events, the most famous of which are the auroras that occur at the poles.

Aurora. Source: noaa.gov

If the Sun undergoes a magnetic reversal once every 11 years, why are we talking about it now? Isn’t it the norm for the Sun, like day and night for the Earth? Well, solar maxima (times of peak activity) happen at an 11-year frequency, but not all maxima are the same. During some years, the CMEs and other solar events happen with much higher intensity than usual, and 2022 appears to be one of them.

Given the varying intensities of solar flares, the US NOAA (National Oceanic and Atmospheric Administration) employs a scale to denote the amount of electromagnetic radiation emitted by a particular solar event. The scale ranges from M1 to X20, where M1 can result in a minor radio blackout, and X20 can result in an extreme one. X-class flares are colossal bursts of energy, often several times the size of the Earth, arcing across the Sun’s surface. A solar flare and its accompanying communications issues can be measured and classified on the NOAA scale in terms of the magnetic flux, which measures how much of the magnetic field passes through a given surface. In a nutshell, the higher the flux, the denser the magnetic field, and in our case, the more severe the interference with radio systems.

A solar flare, with the Earth for scale. Source: jpl.nasa.gov

All this talk of vast amounts of energy being launched from the solar surface might be somewhat terrifying in its implications for humans. Don’t worry; you’re not in impending danger of being barbequed. The Earth’s atmosphere serves as an excellent absorption medium and prevents the radiation from frying us to a crisp. What’s the problem, then? Why do we need to think about solar flares beyond observation purposes?

The answer lies in the atmosphere itself. When Earth’s atmosphere absorbs immense amounts of radiation, it gets ionised, and radio waves travelling through the atmosphere interact with the newly ionised particles and lose energy. En masse, this results in radio blackouts, something that our highly connected world would be troubled by, given how much we rely on instantaneous connection and communication.

Here’s another side effect of solar flares: they can jeopardise the safety of astronauts attempting interplanetary or Earth-Moon travel. The lack of atmosphere to absorb radiation in space would mean that astronauts outside enclosed areas would have very little time to get to safety before the storm hit. Sounds like something out of sci-fi, doesn’t it?

Several times , actually, though only three flares this year have been strong enough to come under X-class. On April 19th, 2022, the Sun launched its strongest flare this year, at X2.2 on the NOAA scale. Its image shown below highlights the portions of it that belong to the extreme ultraviolet part of the spectrum. This flare is particularly worrisome for us, given that the X1.1 flare on April 17th led to radio blackouts and GPS disruptions in part of Asia and Australia. NASA claims that the oncoming solar storm may cause similar difficulties again, affecting VHF radio signals, GPS operations and consequently flights as well. While it may not lead to power outages, the storm may lead to fluctuations that could possibly damage electronic devices which are plugged in at the time.

The X2.2 solar flare, colorized. Source: blogs.nasa.gov

With the Sun entering the most active phase of its cycle, it’s clear that we can expect more such solar activity in the coming days. What does that mean for us? How widespread will its impact be? Is there anything we can do to mitigate the effect it will have on our communications systems? These are questions we should definitely be asking ourselves. What do you think?

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