When astronomers look at distant objects—far away in both space and time—all too often, dust gets in their eyes. Well, not eyes, exactly—in their telescopes' line of vision. It's hard to take a close look at a galaxy formed, say, some five billion years ago, because there's a lot of particulate matter floating in the galaxy itself that blocks a clear view.

The dust in between stars is made up of little grains of things like carbon, silicon, and iron. “Places where stars form are filled with cold, dense gas, and are rich in dust—that’s why star formation is very obscured by dust in general.” The interstellar dust provides a lot of the raw materials for the eventual planet formation, too.

“Therefore, if the properties of the dust in distant galaxies are similar to those of our own Milky Way, then we expect the properties of their planets to be similar, too.”