Astronomers have found the edge of the Milky Way at last

Amazing stuff!

"... Astronomers have long known that the brightest part of the Milky Way, the pancake-shaped disk of stars that houses the sun, is some 120,000 light-years across. Beyond this stellar disk is a disk of gas. A vast halo of dark matter, presumably full of invisible particles, engulfs both disks and stretches far beyond them. But because the dark halo emits no light, its diameter is hard to measure. ...
To find the Milky Way’s edge, [researchers] conducted computer simulations of how giant galaxies like the Milky Way form. In particular, the scientists sought cases where two giant galaxies arose side by side, like the Milky Way and Andromeda, our nearest giant neighbor, because each galaxy’s gravity tugs on the other. The simulations showed that just beyond the edge of a giant galaxy’s dark halo, the velocities of small nearby galaxies drop sharply. ..."

"... Using the current dwarf galaxy population, we predict the edge of the Milky Way halo to be 292 +/- 61 kpc."

Astronomers have found the edge of the Milky Way at last | Science News Our galaxy spans 1.9 million light-years, a new study finds

Here is the link to the respective research paper (in preprint; open access):

The Edge of the Galaxy