How large is the biggest galaxy in the Universe? | by Ethan Siegel | Starts With A Bang! | Dec, 2024

MarylandDigitalNews.comSCIENCE

posted on Dec. 16, 2024 at 3:14 pm

This view of galaxy IC 1101 in size the galaxy cluster Abell 2029 is deceptive: this isn’t a single, normal galaxy orbited by a slew of dwarf galaxies and globular clusters, but rather the largest giant elliptical galaxy known, alongside many other galaxies larger than even the Milky Way. (Credit: Pan-STARRS)

It was barely a century ago that we thought the Milky Way encompassed the entirety of the Universe. Now? We’re not even a special galaxy.

Compared to our Solar System, galaxies simply outclass us.

A logarithmic chart of distances, showing the planets, the Voyager spacecraft, the Oort Cloud, and our nearest star: Proxima Centauri. The Sun may be 109 times the diameter of Earth, but the Earth-Sun distance is over 100 times larger than the Sun’s diameter; the distance to Voyager 1 or 2 is ~100 times larger than the Earth-Sun distance; the Oort Cloud’s density peaks ~100 times farther away than Voyager 2, and the distance to the nearest stars are ~100 times farther away than even that. (Credit: NASA/JPL-Caltech)

The smallest known galaxy, Segue 2, only contains ~1000 stars total.

Only approximately 1000 stars are present in the entirety of the smallest dwarf galaxies such as Segue 1, 2, and 3. Gravitationally, the masses of these galaxies can be estimated at around 550,000–600,000 Suns. The stars making up the dwarf satellite Segue 1 are circled here. These galaxies have the largest dark matter-to-normal matter ratios known. (Credit: Marla Geha/Keck Observatory)

Even these dwarfs extend for hundreds of light-years: billions of times larger than even the largest stars.

This illustration shows some of the largest stars in the Universe, along with the orbits of Saturn (brown ellipse) and Neptune (blue ellipse) for comparison. The stars, from left to right, are the largest blue hypergiant, yellow hypergiant, orange hypergiant, and then the largest two stars of all: the red hypergiants UY Scuti and Stephenson 2–18. The largest stars are approximately 2,000 times the diameter of our Sun, but the temperatures at the surfaces of these stars range from only a few thousand K all the way up to Wolf-Rayet stars, with temperatures of ~200,000 K. (Credit: SkyFlubbler/Wikimedia Commons)

Galaxies can obtain tremendous sizes, but illustrations are often woefully inaccurate.

A common image showing relative sizes (incorrectly) for a number of galaxies. Andromeda is too large for the Milky Way; M87 is too small for Andromeda; IC 1101 is way too small compared to M87. When it comes to comprehending distance scales, it’s vital to not share misleading images. (Credit: Astro Bob/Bob King)

MarylandDigitalNews.comDecember 16, 2024

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