Ever since other galaxies were discovered, we’ve wondered, “which is the largest?“
Most galaxies are smaller than ours, with under 1% of the Milky Way’s stars.
In physical extent, the Milky Way’s stars span a diameter of ~130,000 light-years.
Andromeda, just next door, is almost twice the size: ~220,000 light-years.
Tidally interacting galaxies, however, occupy much grander scales.
The largest known spiral is UGC 2885: 832,000 light-years across.
Elliptical galaxies, particularly in cluster cores, achieve superior sizes.
Messier 87, the Virgo Supercluster’s largest, spans 980,000 light-years across.
The Phoenix Cluster’s brightest central galaxy measures 2,200,000 light-years in size.
But IC 1101, at cluster Abell 2029‘s center, has the largest stellar extent.
With a 6,000,000 light-year diameter, no galaxy’s stars cover greater lengths.
Beyond the stars, however, galaxies possess matter-rich halos.
Although non-luminous in optical light, they can shine in the radio.
Active black holes create jets, which excite gas and trigger emissions.
Giant radio galaxies possess lobes: the largest galactic structures of all.
In 2022, astronomers identified lobes emitted from giant radio galaxy Alcyoneus.
They span 16,000,000 light-years in extent, breaking all prior records.
No other galaxy, even IC 1101, can compare: Alcyoneus is the largest known galaxy of all.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.