Why is it in the News?

Recently the Earth was hit by an X-class solar flare that was strong enough to ionize part of the planet's atmosphere.

What are Solar Flares?

• Solar flares are large explosions from the surface of the sun that emit intense bursts of electromagnetic radiation.
• The intensity of the explosion determines what classification the flare belongs to.
  • The most powerful are X-class flares, followed by M-, C-, and B-class; A-class flares are the smallest.
• These flares can be visible as bright flashes in a particular region of the sun and can last several minutes.
• Solar flares occur when magnetic energy builds up in the solar atmosphere and is released suddenly.
  • These outbursts are intrinsically linked to the solar cycle — an approximately 11-year cycle of solar activity driven by the sun's magnetic field.

What Causes Solar Flares?

• The sun's surface is a magnetically mixed-up place.
• Magnetic fields are created from electrically charged gases generating electrical currents that act as a magnetic dynamo inside the sun.
• These magnetic fields twist, tangle, and reorganize themselves due to the turbulent nature of the gases that create them.
• This unsettled magnetic field behavior — also known as solar activity — can trigger solar flare eruptions from the surface that release vast amounts of electromagnetic radiation — a form of energy that includes radio waves, microwaves, X-rays, gamma rays, and visible light.
• Solar flares tend to originate from regions of the solar surface that contain sunspots — darker, cooler portions of the solar surface where magnetic fields are particularly strong.
  • As such, the number of sunspots can indicate the likelihood of a solar flare eruption.
• Solar activity follows an approximately 11-year cycle with the peak of sunspot activity coinciding with the solar maximum and a sunspot hiatus coinciding with the solar minimum.
• During periods of low solar activity when no sunspots are present, it is unlikely that a solar flare will occur. 

What are X-Class Solar Flares?

• Solar flares are categorized into five classes based on the intensity of emitted X-rays, with each class letter denoting a 10-fold increase in energy output, akin to the Richter scale for earthquake strength assessment.
• X-class flares are the most powerful solar flares.
  • Then there are M-class flares that are 10 times smaller than X-class flares, then C-class, B-class, and finally A-class flares which are too weak to significantly affect Earth.
• Within each letter class, a finer scale from 1 to 9 gives the flare assessment greater precision with larger numbers representing more powerful flares within the class.
• However, X-class flares can break this nine-point rating mold with higher ratings, since there is no class more powerful than X-class.
• Fortunately, X-class flares occur on average about 10 times per year.

How do Solar Flares Affect the Earth?

• Disruption of Satellite Communications: Solar flares can interfere with satellite communications, GPS signals, and radio transmissions, causing disruptions or blackouts in telecommunications and navigation systems.
• Auroral Displays: Intense solar flares can trigger colorful auroras, or Northern and Southern Lights, as charged particles interact with Earth's magnetic field, creating stunning light displays in the polar regions.
• Power Grid Disturbances: Severe solar flares have the potential to induce geomagnetic storms that can overload power grids, leading to widespread power outages and damage to electrical infrastructure.
• Radiation Hazards: Solar flares emit harmful radiation, particularly in the form of ultraviolet and X-rays, which can pose risks to astronauts in space and airline passengers at high altitudes.
• Impact on Electronics: The influx of charged particles during solar flares can induce currents in electrical circuits, potentially damaging or disrupting sensitive electronic devices, such as computers, satellites, and spacecraft.