Astronomers have made a measurement of a distant neutron star that is one million times more precise than the previous world's best - and they did it by using...nothing.
The interstellar medium is the 'empty' space between stars and galaxies. It's not really empty, it is made up of sparsely spread charged particles and those can be used as a giant lens. The astronomers did just that, to magnify and look closely at the radio wave emission from a small rotating neutron star.
Result: the highest resolution measurement ever achieved, equivalent to being able to see the double-helix structure of our genes from the Moon.