Earth whistles when lightning strikes, and there’s a new melody

Earth whistles when lightning strikes, and there’s a new melody

Sub: Sci

Sec: Space

• Recent research found that lightning energy can generate a new type of whistler wave by reflecting from the ionosphere into the magnetosphere.
• This challenges previous beliefs and may double the lightning energy entering the magnetosphere, affecting Van Allen belt calculations.

Why does the Earth whistle when lightning strikes?

• Earth’s magnetosphere protects the planet by trapping charged particles from the Sun and cosmic radiation in the Van Allen radiation belts.
• Lightning strikes release electrical energy as electromagnetic waves, some of which are known as whistler waves.
• These waves travel along Earth’s magnetic field lines, moving between the northern and southern hemispheres.
• The frequencies of whistler waves are within the human hearing range (20–20,000 Hz) and can travel at speeds up to a tenth of the speed of light.

New Research:

• Recent research from the University of Alaska Fairbanks discovered a new type of whistler wave generated by lightning energy reflected from the ionosphere into the magnetosphere.
• This new wave mechanism suggests that more lightning energy may enter the magnetosphere than previously thought.
• The finding could impact calculations of lightning’s effects on the Van Allen belts and has implications for space exploration.

Van Allen belts

• The Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind. The particles are captured by and held around a planet by that planet’s magnetic field. It surrounds Earth, containing a nearly impenetrable barrier that prevents the fastest, most energetic electrons from reaching Earth.
• The outer belt is made up of billions of high-energy particles that originate from the Sun and become trapped in Earth’s magnetic field, an area known as the magnetosphere. The inner belt results from interactions of cosmic rays with Earth’s atmosphere.
• Discovered by James Van Allen in 1958, these belts protect Earth from solar and cosmic radiation by confining particles within them.
• They play a crucial role in space weather, influencing satellite operations and astronaut safety.

Can you see the Van Allen radiation belt?

Although images of the Van Allen radiation belts make them look visible and colorful, this is actually just a representation. The radiation belts themselves are so dilute that astronauts don’t even see or feel them when they are outside in their spacesuits. In fact, scientists only detect them using sensitive instruments inside satellites and spacecraft.