GS PAPER III: Science and Technology- developments and their applications and effects in everyday life.

Context: NASA's Voyager 1 detects the eerie hum of interstellar space. The Voyager 1 spacecraft, launched in September 1977, is currently located about 22.7 billion km from Earth.

More about news:

• Instruments aboard NASA's Voyager 1 spacecraft, which nine years ago exited our solar system's outer reaches, have detected a faint monotonous hum caused by the constant vibrations of the small amounts of gas found in the near-emptiness of interstellar space.
• It essentially represents the background noise present in the vast expanse between star systems.

Persistent plasma waves

• These vibrations, called persistent plasma waves, were identified at radio frequencies in a narrow bandwidth during a three-year period as Voyager 1 traverses interstellar space.
• The persistent plasma waves are far too weak to actually hear with the human ear.
• If we could hear it, it would sound like a single steady note, playing constantly but changing very slightly over time.

A global selfie

• The Voyager 1 spacecraft, launched in September 1977, is currently located about 14.1 billion miles (22.7 billion km) from Earth — roughly 152 times the distance between our planet and the sun — and is still obtaining and transmitting data.
• Having decades ago visited the huge planets Jupiter and Saturn, Voyager 1 is now providing insight into interstellar space.
• The immense regions between star systems in a galaxy are not a complete vacuum.
• The stew of matter and radiation present in low densities — mostly gas — is called the interstellar medium.
• About 15% of the visible matter in our Milky Way galaxy is composed of this interstellar gas, dust and energetic particles like cosmic rays.
• Much of the interstellar medium is in what is called an ionized, or electrically charged, state called plasma.
• Interstellar plasma is extremely diffused, there are about 0.1 atoms for every cubic centimeter, whereas the air we breathe on Earth has billions of atoms for every cubic centimeter.
• Voyager 1 previously detected disturbances in the gas in interstellar space triggered by occasional flares from our sun.
• The new study instead reveals the steady vibrations unrelated to solar activity that could be a constant feature in interstellar space. This hum has a frequency of about 3 kilohertz (kHz).

Voyager 1

• It is the most distant human-made object in space.
• Voyager 1 will keep going but its power supply will run out most likely this decade after up to 50 years of service

https://www.thehindu.com/sci-tech/science/nasas-voyager-1-detects-the-eerie-hum-of-interstellar-space/article34539865.ece?homepage=true

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