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Voyager Glossary
September 12, 2013

Interstellar space: the space between stars, comprised of dust, gas and plasma, which is ionized gas.

Solar system: the gravitational zone of influence around a star (such as our sun), which includes planets and comets in orbit around it. Scientists now define our solar system as the region surrounding our sun, which contains the eight planets and extends into the Oort Cloud.

Oort Cloud: a theoretical band of material containing icy bodies at the edge of our solar system, from which long-period comets emerge and approach close to the sun on a recurring schedule.

In our solar system lie the following zones:

  • Heliosphere, also known as the solar bubble: the bubble of plasma that the sun blows around itself. Beyond the heliosphere are the Oort Cloud and interstellar space.
  • Heliosheath: the turbulent outer layer of the heliosphere
  • Heliopause: the final boundary that divides the heliosphere and interstellar space

Plasma: ionized gas that consists of positive ions and separated electrons (electrified particles) and is one of the fundamental states of matter. It is the densest and slowest-moving of charged particles in space. One good example on Earth is the glowing material in a neon sign. 

Galactic cosmic rays: speedy, high-energy charged particles or ions that originate from far outside our solar system.  They were accelerated by the shock waves caused by the supernovae explosions of nearby giant stars millions of years ago.  Voyager 1 began to encounter these particles in greater numbers once it approached interstellar space. Although the fastest cosmic rays make their way to Earth, slower cosmic rays cannot enter the heliosphere and are present only in interstellar space.

Solar wind: a streaming wind of plasma, or ionized atoms, emitted from the sun, It exists because the temperature of the sun is so high its gravity is not able to hold onto the plasma.

Magnetic field lines: lines that emanate from one magnetic pole to the other and can serve as paths along which charged particles move. The field lines have a direction and an intensity. Flowing plasma can carry a magnetic field.  Because the sun is spinning, the magnetic field lines from the sun form a spiral, like a twirling skirt, as they are carried outward by the solar wind plasm

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Page Last Updated: September 12th, 2013
Page Editor: Tony Greicius