The dimming of light traveling in the interstellar space due to the combined effects of absorption and scattering by interstellar dust particles. Interstellar extinction increases at shorter (bluer) w
avelengths, resulting in interstellar reddening.
A large-scale, weak magnetic field, with an estimated strength of about 1 to 5 microgauss, that pervades the disk of the Milky Way Galaxy and controls the alignment of interstellar dust grains.
The environment containing the interstellar matter (the gas and dust that exists in open space between the stars), consisting of gas (mostly hydrogen) and dust. Even at its densest phase, the interste
llar medium is emptier than the best vacuum man can create in the laboratory, but because space is so vast, the interstellar medium still adds up to a huge amount of mass.
Any molecule that occurs naturally in clouds of gas and dust in the interstellar medium. So far more than 140 species have been discovered, many of which nonexistent on Earth.
A body other than a star or substellar object not gravitationally bound to a star. Its hyperbolic orbit would indicate an object not bound to the Sun. The first known ISO is 1I/'Oumuamua. ISOs are icy
planetesimals that are expected to behave like the long-period comets of the solar system; volatile ices sublimate when the ISO approaches the Sun, developing a coma and a dust tail -- features that should make them bright and therefore easy to spot. The rocky ISOs, on the other hand, only reflect sunlight. As their albedo is expected to be extremely low they become dark (after eons of bombardment by high-energy cosmic rays), they would be extremely faint and hard to detect.
The dimming of light during its travel in the interstellar medium due to absorption by intervening dust grains. Since shorter wavelengths are particularly affected, the spectrum of the light is increa
singly dominated by the long wavelength end of the spectrum. As a result, the light is 'reddened' as it travels through space. Robert J. Trumpler (1886-1956), a Swiss-American astronomer, was the first to produce a definite evidence of the existence of interstellar extinction and to estimate its magnitude (1930).