For two decades, astronomers have believed that the galaxy has a lot more mass than is visible, because outer stars are speeding around as if it weighs a lot more.
Astronomers trying to track down the missing stuff call it dark matter.
A team of American and Australian astronomers believes periodic spurts of extra light from distant stars provide evidence that could help account for about half the missing parts of the Milky Way. Something is causing these stars to brighten incredibly for about 80 days, and that something is probably the same dark matter that accounts for the galaxy's hidden weight, said team leader Charles Alcock of the Lawrence Livermore Laboratory. The team's research findings were released in Australia this week. They believe such objects exist in a halolike swarm around our galaxy. Since the team found 20 machos in a relatively tiny slice of the galaxy, it figures these invisible objects can account for about half the mass of the galaxy, or about 325 billion times the weight of our sun, Alcock said.