Table 1 shows a breakdown of the properties of the components of the ISM of the Milky Way.
Field, … See more

The ISM is usually far from thermodynamic equilibrium. Collisions establish a Maxwell–Boltzmann distribution of velocities, and the 'temperature' normally used to describe interstellar gas is the 'kinetic tem… See more

Despite its extremely low density, photons generated in the ISM are prominent in nearly all bands of the electromagnetic spectrum. In fact the optical band, on which astronomers relied until well into the 20th century, is t… See more

Radio waves are affected by the plasma properties of the ISM. The lowest frequency radio waves, below ≈ 0.1 MHz, cannot propagate through the ISM since they are below its plasma frequency. At higher frequencies… See more

The word 'interstellar' (between the stars) was coined by Francis Bacon in the context of the ancient theory of a literal sphere of fixed stars. Later in the 17th century, when the idea that stars were scattered through infinite spa… See more

• Astrophysical maser
• Diffuse interstellar band
• Fossil stellar magnetic field
• Heliosphere… See more