If you reckoned our Milky Way galaxy was impossibly huge, spare a though for NGC 6872.
At an astounding 522,000 light-years from tip-to-tip -- five times the size of the Milky Way -- this gargantuan galaxy was confirmed last week as the largest-known in the observed universe.
Scientists at NASA's Galaxy Evolution Explorer mission, or GALEX, confirmed the sheer extent of NGC 6872 by re-examining archival data using super-sensitive far-ultraviolent methods, added to images from the European Southern Observatory and NASA's Spitzer Space Telescope.
"Without GALEX's ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system," lead scientist Rafael Eufrasio said.
NGC 6872 is located around 212 million light-years away from earth, in the constellation Pavo, where it is interacting with a much smaller disk-shaped galaxy, IC 4970.
While scientists theorize large galaxies grow by merging with smaller ones, NGC 6872 may actually be doing the opposite.
The researchers say the gravitational interaction between that galaxy and its smaller companion may actually spawn a new small galaxy, made up of rich, hot stars less than 200 million years old.
The findings were reported at a meeting of the American Astronomical Society in Long Beach, California.