Astronomers just found the smallest galaxy ever | by Ethan Siegel | Starts With A Bang! | May, 2025
With stars, gas, and dark matter, galaxies come in a great array of sizes. This new one, Ursa Major III/UNIONS 1, is the smallest by far.
When it comes to the galaxies in the Universe, most of us think about the Milky Way and galaxies similar to it. After all, it is our galactic home, containing hundreds of billions of stars and spanning more than 100,000 light-years across. It’s an interesting fact that galaxies comparable in size to the Milky Way (as well as larger ones) hold the majority of stars present within the Universe today, but that they only represent about ~1% of all galaxies, overall. The majority of galaxies present in the Universe are:
- small,
- low in mass,
- contain very few numbers of stars, overall,
- but are dominated largely by dark matter.
Most of the galaxies in the Universe, because they’re small and contain very few stars within them, are also exceedingly difficult to detect: they’re also ultra-faint galaxies. It takes wide, deep surveys to reveal them at all, and even once they’re imaged, the stars within them need to be measured individually to determine that they’re all at the same distance, and that they’re all…
Source link
