Nebulae are vast clouds of stellar material composed primarily of hydrogen, along with trace amounts of other elements and compounds. In terms of size, nebulae vary greatly. Some may only be the size of our solar system, while others can span millions of light years. What are the five largest nebulae ever discovered?
1. NGC 262 Halo Cloud
NGC 262 is one of the largest known spiral galaxies in the universe, and is surrounded by the largest known nebulae as well. The galaxy itself is located 287 million light-years away in the constellation Andromeda. The nebula that surrounds it is more than 50 billion times the mass of the Sun and spans a distance of more than one million light-years. The nebula is thought to be a remnant of other small galaxies that merged with NGC 262, with some of its material falling around the large galaxy in the form of a vast halo of stellar material.
2. The Lion’s Ring
The Leo Ring is a vast ring of galactic material orbiting two galaxies at the center of the Leo Cluster of galaxies about 38 million light-years away. The Leo Ring spans a distance of 650,000 light-years and is believed to have formed during the galaxy collision that occurred between the two galaxies orbiting it.
3. Magallenic Stream
The Magallenic Stream is a vast stream of stellar material that connects two satellite galaxies of the Milky Way, the Small and Large Magallenic Clouds. The stream itself extends at a distance of about 600,000 light-years, and is found outside the Milky Way. How exactly this structure formed is still somewhat mysterious, however it is likely that it formed as a result of gravitational interactions between the Milky Way and the two dwarf galaxies, as well as clouds caused by gas and dust within the Milky Way.
LAB-1 is a massive structure of gas and dust located in the constellation Aquarius at a distance of 11 billion light-years. The structure is 300,000 light-years wide and was discovered by chance. While studying galaxies in the early universe, astronomers stumbled upon this massive structure of intergalactic material. From afar, the nebula appears green due to the amount of redshift caused by the velocity of the structure, which combines with the ultraviolet light of the structure to make it appear green.
5. Himiko gas cloud
The Himiko gas cloud is one of the most distant nebulae known in the universe, more than 12 billion light-years away. The nebula itself spans a distance of 55,000 light-years. Interestingly, the Himiko gas cloud is believed to be a protogalaxy, which means that it is a structure that transforms into a galaxy.
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