The Before Times of a Solar System

Read: A baby planet is born

“It’s an unexplored area,” says Johanna Teske, an astronomer at the Carnegie Institution for Science, who was not involved in the new research.

According to theories of planet formation, a baby planet’s position inside a protoplanetary disk dictates what kind of world it turns out to be. Gaseous worlds—like Jupiter and Saturn—arise farther out from their star, where it’s cold enough for molecules to condense into ice and stay that way. Rocky worlds—like Earth and Mars—coalesce closer in, where the warmth of the star tends to evaporate icy material, but spares bits of rock. The thought of peering into these inner regions and searching for rocky planets, the only planets on which we know that life can arise, is a tantalizing one indeed.

None are visible in these images, mind you, but there are a few hints. Growing baby planets can perturb nearby matter in these disks, twisting and bending it. The indentations in some of the disks could be signs of material gathering in little whirlpools and sticking together, forming clumps with enough gravity of their own to tug at their surroundings.

Astronomers have found similar hints in other, more zoomed-out observations of protoplanetary disks. The rings in images like this one, for example, are likely the result of lurking planets carving a path through the dust and gas as they circle their star.

In 2018, astronomers even captured photographic evidence of a planet bending clouds of dust and gas around its young star, known as HL Tauri, as it swirled into being. They scrutinized the faint light emanating from the planet and discovered that it is an extremely hot, gaseous planet several times the mass of Jupiter. Perhaps another blood-orange-ish splotch to the rest of us, but a momentous discovery to researchers.

The newly released images are not quite photographs, at least not like the one above is. To observe the inner edges of these disks, astronomers blended together starlight absorbed by four different ground-based telescopes. This is a delightful hack in astronomy work: If a telescope isn’t powerful enough to see a target, make a bigger one by syncing a bunch of small telescopes so that they scan the skies as one. (This is the same technique that produced the first-ever image of a black hole, which took 10 telescopes across four continents.)

Read: A new planet or a red herring?

The researchers then combined those data with mathematical models to reconstruct the finer details of the disks. The final result is a reconstruction of the real thing, though several astronomers who weren’t involved in the research tell me it’s a very good one. According to Jacques Kluska, the lead author of the research and an astronomer at KU Leuven, a university in Belgium, the views of the inner disks would amount to only a few pixels in a direct image from a single, powerful telescope. “These are pretty unprecedented physical scales,” says Kate Folette, an astronomer at Amherst College who uses ground-based telescopes to search for planets around young stars, and wasn’t involved in the latest work.