Planets are thought to form from the dust and gas that encircles young stars in a disk. Over time, dust particles stick together, until they build up bigger clumps. Eventually, these have enough mass that gravity becomes significant, and over millions of years the clumps crash together to make planets and moons. In our own Solar System, this process took place about 4500 million years ago, with the giant planet Jupiter the first to form.

Since the 1990s, astronomers have found both disks of gas and dust, and nearly 2000 fully formed planets, but the intermediate stages of formation are harder to detect.

Dr Greaves and team colleague Dr Anita Richards from the University of Manchester used the e-MERLIN array of radio telescopes centred on Jodrell Bank, Cheshire, and that stretches across England in a so-called interferometer, mimicking the resolution of a single large telescope.

The scientists used the interferometer to observe the star DG Tauri, a relatively youthful star just 2.5 million years old and 450 light years away in the constellation of Taurus. Looking at radio wavelengths, they discovered a faint glow characteristic of rocks in orbit around the newly formed star.