Measuring the distances to astronomical objects is hard work. But it’s critical for understanding the universe. Unless you know how far away an object is, you can’t know its brightness, its size, its gravity, or anything else about it. An example of just how tough the job is is the Pleiades star cluster — also known as the Seven Sisters. It climbs into good view in the east by around 10 p.m., and looks like a tiny dipper. Astronomers have been studying the Pleiades since the invention of the telescope. Even so, measuring its distance hasn’t been easy. The most accurate technique is called parallax. Astronomers look at the stars of the Pleiades when Earth is on opposite sides of the Sun. That produces a tiny shift in the position of the stars. The angle of the shift reveals their distance — about 430 light-years according to most studies. Recently, though, a team of astronomers used a network of radio telescopes to make new measurements. The network produces images that are unusually sh
