July 17, 2017 by Mara Johnson-Groh Space is not empty, nor is it silent. The region around Earth is filled with magnetic field lines and trapped energetic particles, zooming about in a high-speed dance around the planet (shown here in an illustration). Credit: NASA's Goddard Space Flight Center/Brian Monroe

Space is not empty, nor is it silent. While technically a vacuum, space nonetheless contains energetic charged particles, governed by magnetic and electric fields, and it behaves unlike anything we experience on Earth. In regions laced with magnetic fields, such as the space environment surrounding our planet, particles are continually tossed to and fro by the motion of various electromagnetic waves known as plasma waves. These plasma waves, like the roaring ocean surf, create a rhythmic cacophony thatwith the right toolswe can hear across space.

Just as waves roll across the ocean or storm fronts move through the atmosphere, disturbances in space, can cause waves. These waves occur as fluctuating electric and magnetic fields plow through clumps of ions and electrons that compose the plasma, pushing some to accelerated speeds. This interaction controls the balance of highly energetic particles injected and lost from in the near-Earth environment.

One type of plasma wave fundamental to shaping our near-Earth environment are whistler-mode waves. These waves create distinct sounds dependent on the plasma they travel through. For example, the region tight around Earth, called the plasmasphere, is relatively dense with cold plasma. Waves traveling inside this region sound much different than those outside. While different whistler-mode waves sing different sounds, they all move in the same way, with the same electromagnetic properties.

When lighting strikes the ground, the electrical discharge can also trigger whistler-mode plasma waves. Some of the waves escape beyond the atmosphere to bounce like bumper cars along Earth's magnetic field lines between the north and south poles. Since the lightning creates a range of frequencies, and since higher frequencies travel faster, the wave howls a falling pitch, giving the wave its namea whistler.

Out beyond the plasmasphere, where the plasma is tenuous and relatively warm, whistler-mode waves create primarily rising chirps, like a flock of noisy birds. This type of wave is called chorus and is created when electrons are pushed towards the night side of Earthwhich in some cases, may be caused by magnetic reconnection, a dynamic explosion of tangled magnetic field lines on the dark side of Earth. When these low energy electrons hit the plasma, they interact with particles in the plasma, imparting their energy and creating a unique rising tone.

Whistler-mode waves traveling inside the plasmasphere are called plasmaspheric hiss and sound a lot like radio station static. Some scientists think hiss is also caused by lightning strikes, but others think it could be caused by chorus waves that have leaked inside the plasmasphere. Both chorus and hiss waves are key shapers of the near-Earth environment including the Van Allen radiation belts, doughnut-shaped rings of high-energy particles encircling the planet.

The video will load shortly

NASA scientists, with the help of the Van Allen Probes mission, are working to understand the dynamics of plasma waves to improve predictions of space weather, which can have damaging effects on satellites and telecommunications signals. As a part of their observations, the scientists have recorded these eerie sounds made by different plasma waves in the particle symphony surrounding Earth.

NASA's two Van Allen Probe spacecraft use an instrument called EMFISIS, short for Electric and Magnetic Field Instrument Suite and Integrated Science, to measure electric and magnetic waves as they circle Earth. As the spacecraft encounter a wave, sensors record the changes in the frequency of the electric and magnetic fields. The scientists shift the frequencies to the audible range so that we can listen to the sounds of space.

The video will load shortly

By understanding how waves and particles interact, scientists can learn how electrons are accelerated and lost from the radiation belts and help protect our satellites and telecommunications in space.

The video will load shortly

Explore further: Making waves with the hot electrons within Earth's radiation belts

Encircling the Earth, within its magnetosphere, are two concentric, doughnut-shaped radiation belts known as the Van Allen belts. The Van Allen belts swell and recede in response to incoming energy from the sun, sometimes ...

Recent experiments at the Large Plasma Device (LAPD) at the University of California, Los Angeles, have successfully excited elusive plasma waves, known as whistler-mode chorus waves, which have hitherto only been observed ...

We know that there is sound on planets and moons in the solar system places where there's a medium through which sound waves can be transmitted, such as an atmosphere or an ocean. But what about empty space? You may have ...

A Dartmouth-led study sheds light on the impact of plasma waves on high-energy electrons streaking into Earth's magnetic field from space.

High above Earth, two giant rings of energetic particles trapped by the planet's magnetic field create a dynamic and harsh environment that holds many mysteriesand can affect spacecraft traveling around Earth. NASA's Van ...

In a new study that sheds light on space weather's impact on Earth, Dartmouth researchers and their colleagues show for the first time that plasma waves buffeting the planet's radiation belts are responsible for scattering ...

(Phys.org)An international team of astronomers has performed detailed measurements of the chemical composition of 158 red giant stars in the nearby Sagittarius dwarf galaxy. The study, presented in a paper published July ...

(Phys.org)A pair of researchers with Aberystwyth University in the U.K. has used data from NASA's Solar Dynamics Observatory to learn more about how the sun's corona behaves over differing stages of its 11-year cycle. ...

Space is not empty, nor is it silent. While technically a vacuum, space nonetheless contains energetic charged particles, governed by magnetic and electric fields, and it behaves unlike anything we experience on Earth. In ...

NASA's new Neutron star Interior Composition Explorer (NICER) mission to study the densest observable objects in the universe has begun science operations.

One night three months ago, Rosa Castro finished her dinner, opened her laptop, and uncovered a novel object that was neither planet nor star. Therapist by day and amateur astronomer by night, Castro joined the NASA-funded ...

In July 2015, NASA's New Horizons spacecraft sent home the first close-up pictures of Pluto and its moons amazing imagery that inspired many to wonder what a flight over the distant worlds' icy terrain might be like.

Adjust slider to filter visible comments by rank

Display comments: newest first

It's interesting that the author managed to avoid a single usage of the term "double layer" in an article entirely dedicated to plasmas generating noises.

I would learn to surf, or ski, or control a charge distribution such that it accelerates through this sea. We got more to do just listening to the silence!

Note: Charge is its center and its field, at the center is only the field. When a charge oscillates, its field wrinkles as per Maxwell. The relative speed of these wrinkles, or the speed of light is the original wavelength divided by the measured period.

Empty space cannot exist. Charge, apparently never created or destroyed, its field, or the charge, extends from its center to infinity.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Read the original here:

NASA listens in as electrons whistle while they work - Phys.Org