NASA’s Voyager 1 detects the eerie hum of interstellar space
- Instruments aboard NASA’s Voyager 1 spacecraft 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. 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 too weak to actually hear with the human ear. The sound is like a single steady note, playing constantly but changing very slightly over time
- Launched in the 1970’s by NASA to probe outer space
- Voyager 1 departed Earth on 5 September 1977, a few days after Voyager 2 and left our solar system in 2013.
- The mission objective of the Voyager Interstellar Mission (VIM) is to extend the NASA exploration of the solar system beyond the neighborhood of the outer planets to the outer limits of the Sun’s sphere of influence, and possibly beyond.
- The Voyager spacecraft are the third and fourth human spacecraft to fly beyond all the planets in our solar system. Pioneers 10 and 11 preceded Voyager in outstripping the gravitational attraction of the Sun but on February 17, 1998, Voyager 1 passed Pioneer 10 to become the most distant human-made object in space.
- 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. Voyager 1 is 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 diffuse compared to what we’re used to on Earth. In this plasma, 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