To the roots of the solar system: planets in the making observed

Planetary systems like our own share a humble origin as mere by-products of star formation. A newborn star's gravity gathers leftover gas and dust in a dense, flattened disk of matter orbiting the star.

This image taken with the HiCIAO planet-hunter camera on Subaru Telescope shows a bright arc of scattered light (white) from the protoplanetary disk around the young star LkCa 15 (centre, masked out with a dark circle). The arc's sharp inner edge traces the outline of a wide gap in the disk. The gap is decidedly lopsided – it is markedly wider on the left side – and has most likely been carved out of the disk by one or more newborn planets that orbit the star. © MPIA (Christian Thalmann) & NAOJ

Clumps in the disk sweep up more and more material, until their own gravity becomes sufficiently strong to compress them into the dense bodies we know as planets.

Recent years have seen substantial advances both in observations (mostly indirect) and in theoretical modelling of such ''protoplanetary'' disks.

The two new observations have added intriguing new details, revealing some structures that had never before been seen directly.