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Lyman alpha nebulae around quasars can have sizes between 15 kpc and 460 kpc. [1] Especially large Enormous Lyα nebula (ELAN) can have large sizes of ≳100 kpc. [2] Farina et al. 2019 table 5 has an extensive compilation of Lyman alpha nebulae around quasars. [1] For now this list contains only the largest ELANs, with sizes larger than 300 kpc.
Earth's air has a density of approximately 10 19 molecules per cubic centimeter; by contrast, the densest nebulae can have densities of 10 4 molecules per cubic centimeter. Many nebulae are visible due to fluorescence caused by embedded hot stars, while others are so diffused that they can be detected only with long exposures and special filters.
The third form of rock material found on Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on the Earth's surface include quartz, the feldspars, amphibole, mica, pyroxene, and olivine. [25]
A typical planetary nebula is roughly one light year across, and consists of extremely rarefied gas, with a density generally from 100 to 10,000 particles per cm 3. [42] (The Earth's atmosphere, by comparison, contains 2.5 × 10 19 particles per cm 3.) Young planetary nebulae have the highest densities, sometimes as high as 10 6 particles per ...
Box Nebula NGC 6445: 1786 4.5 11.2 Sagittarius: Eye of Sauron Nebula M 1-42: 10 14 Sagittarius
Many trans-Neptunian objects (TNOs) have been discovered; in many cases their positions in this list are approximate, as there is frequently a large uncertainty in their estimated diameters due to their distance from Earth. Solar System objects more massive than 10 21 kilograms are known or expected to be approximately spherical.
Porous chondrite dust particle. 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]
The Omega Nebula is between 5,000 and 6,000 light-years from Earth and it spans some 15 light-years in diameter. The cloud of interstellar matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. [3] The total mass of the Omega Nebula is an estimated 800 solar masses. [4]