  In 2018, images were released of a planet being formed around the star PDS
70, offering a tantalizing glimpse into how planets come into being. However,
many questions remain about how dust evolves into planets, and astrophysical
observations are unable to provide all the answers. It is therefore necessary
to perform experiments to reveal key details and, to avoid unwanted effects
from the Earth's gravitational pull, it is often necessary to perform such
experiments in microgravity platforms. This Review sketches current models of
planet formation and describes the experiments needed to test the models.
