20 new protoplanetary disks, as imaged by the Disk Substructures at High Angular Resolution Project (DSHARP) collaboration, showcasing what newly-forming planetary systems look like. (S. M. ANDREWS ET AL. AND THE DSHARP COLLABORATION, ARXIV:1812.04040)

20 Incredible New Images Show How Planets First Form Around Stars

For generations, planet formation was only a theory. As 2018 comes to an end, here’s the evidence of what’s going on.

The theory of planet formation has been around for a long time, but lacked validation.

Artist’s impression of a young star surrounded by a protoplanetary disk. There are many unknown properties about protoplanetary disks around Sun-like stars, but they all exhibit infrared radiation. Tabby’s star has none. (ESO/L. CALÇADA)

In principle, gas collapses to form protostars surrounded by protoplanetary disks.

The very young protostar M17-SO1, as imaged way back in 2005 with the ground-based Subaru telescope, shows features of a protoplanetary disk around a newly-forming star, but internal features were unable to be resolved with instrumentation of that time. (SUBARU / NAOJ)

As protostars grow, they heat up, while their disks race to form planets before the volatile material evaporates.

30 protoplanetary disks, or proplyds, as imaged by Hubble in the Orion Nebula. Hubble is a brilliant resource for identifying these disk signatures in the optical, but has little power to probe the internal features of these disks, even from its location in space. (NASA/ESA AND L. RICCI (ESO))

With observatories like Hubble, we’ve found and identified many disks, but couldn’t measure their internal properties.