For the first time, astronomers have directly measured the distance to a spot clear across the galaxy. The established but challenging technique promises a new way to map the structure of the Milky Way.
This technique, called parallax, has measured distances to stars since the 1830s. But because of galactic dust in the way, it has been difficult to use parallax on stars on the opposite side of the galaxy. Other ways to measure distance are saddled with assumptions and uncertainties.