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The visible-light (left) and infrared (right) views of the Trifid Nebula—a giant star-forming cloud of gas and dust located 5,400 light-years away in the constellation Sagittarius Stars are thought to form inside giant clouds of cold molecular hydrogen — giant molecular clouds roughly 300,000 times the mass of the Sun ( M ☉ ) and 20 ...
Permutation City asks whether there is a difference between a computer simulation of a person and a "real" person. It focuses on a model of consciousness and reality, the Dust Theory, similar to the Ultimate Ensemble Mathematical Universe hypothesis proposed by Max Tegmark.
The total mass of the interplanetary dust cloud is approximately 3.5 × 10 16 kg, or the mass of an asteroid of radius 15 km (with density of about 2.5 g/cm 3). [7] Straddling the zodiac along the ecliptic, this dust cloud is visible as the zodiacal light in a moonless and naturally dark sky and is best seen sunward during astronomical twilight.
The interplanetary dust cloud illuminated and visible as zodiacal light, with its parts the false dawn, [3] gegenschein and the rest of its band, which is visually crossed by the Milky Way, in this composite image of the night sky above the northern and southern hemisphere
Cosmic dust – also called extraterrestrial dust, space dust, or star dust – is dust that occurs in outer space or has fallen onto Earth. [ 1 ] [ 2 ] Most cosmic dust particles measure between a few molecules and 0.1 mm (100 μm ), such as micrometeoroids (<30 μm) and meteoroids (>30 μm). [ 3 ]
For stability, the cloud must be in hydrostatic equilibrium, which in case of a spherical cloud translates to = (), where () is the enclosed mass, is the pressure, () is the density of the gas (at radius ), is the gravitational constant, and is the radius. The equilibrium is stable if small perturbations are damped and unstable if they are ...
Intergalactic dust can form intergalactic dust clouds, known since the 1960s to exist around some galaxies. [1] By the 1980s, at least four intergalactic dust clouds had been discovered within several megaparsecs of the Milky Way galaxy, [ 1 ] exemplified by the Okroy Cloud .
In physical cosmology, a protogalaxy, which could also be called a "primeval galaxy", is a cloud of gas which is forming into a galaxy.It is believed that the rate of star formation during this period of galactic evolution will determine whether a galaxy is a spiral or elliptical galaxy; a slower star formation tends to produce a spiral galaxy.