Nebulae are vast clouds of stellar matter that are composed mostly of hydrogen, along with traces of other elements and compounds. In terms of size, nebulae vary greatly. Some may be only the size of our solar system, while others may span millions of light-years. What are the five largest nebulae ever discovered?
1. Halo NGC 262 Cloud
NGC 262 is one of the largest known spiral galaxies in the universe, and it is also surrounded by the largest known nebulae. The galaxy itself is located 287 million light-years away in the constellation Andromeda. The surrounding nebula is over 50 billion times the mass of the sun and spans a distance of over a million light-years. The nebula is believed to be the remnants of other small galaxies that merged with NGC 262, with some of their material falling around the large galaxy as a vast halo of stellar material.
2. The Lion Ring
The Leo Ring is a vast ring of galactic material that orbits two galaxies at the center of the Leo Group 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 a galactic collision that occurred between the two galaxies it orbits.
3. The Magallénique stream
The Magallenic Stream is a vast flow of stellar material that connects the two satellite galaxies of the Milky Way, the Small and Large Magallen Clouds. The stream itself spans a distance of about 600,000 light years and exists just outside the Milky Way. Exactly how this structure formed remains somewhat of a mystery, but it likely formed as a result of gravitational interactions between the Milky Way and the two dwarf galaxies, as well as drag caused by gas and dust in the Milky Way.
LAB-1 is a vast 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 across and was actually discovered accidentally. While studying the galaxies of the early universe, astronomers came across this gigantic structure of intergalactic matter. From a distance, the nebula appears green due to the amount of redshift caused by the speed of the structure, which combines with the structure’s ultraviolet light to make it appear green.
5. Himiko Gas Cloud
The Himiko gas cloud is one of the best-known nebulae in the universe at a distance of over 12 billion light-years. The nebula itself spans a distance of 55,000 light years. Interestingly, the Himiko gas cloud is considered a protogalaxy, meaning it’s a structure that becomes a galaxy.