WASHINGTON (AP) — It's a double cosmic conundrum: Lots of stuff that was already invisible has gone missing.

Astronomers have found a distant galaxy where there is no dark matter.

Dark matter is called "dark" because it can't be seen. It is the mysterious and invisible skeleton of the universe that scientists figure makes up about 27 percent of the cosmos. Scientists only know dark matter exists because they can observe how it pushes and pulls things they can see, like stars.

It's supposed to be everywhere.

But Yale University astronomer Pieter van Dokkum and colleagues spied a vast, old galax...