The PDS 70 system, located nearly 400 light-years away and still in the process of being formed, with planet PDS 70c circled in blue. ALMA (ESO/NAOJ/NRAO)/Benisty et al. Astronomers have captured a distant planet adorned with a moon-making disc for the first time. The planet has captured enough gas and dust in its orbit to make three moons the size of Earth's. By studying this world and its star, astronomers can learn more about how planets and moons are born. See more stories on Insider's business page. For the first time, astronomers have captured an alien moon in the making.Two enormous Jupiter-like planets are orbiting a star about 400 light-years away - and one of them seems to be forming a moon.