Yet what they beheld was ancient-ancient even in terms of planetary formation.

"This will shake up the theory of planetary formation."

The youthful period of exuberant and violent planetary formation, from which had emerged, among others, our own Earth, was over.

Asteroids are thought to include debris left over from the earliest days of planetary formation in the solar system about 4.5 billion years ago.

In the early period of planetary formation, the disk would still be thick with gas and other material.

Either way, their presence suggests that planetary formation is an unexpectedly common and widespread process.

Something like planetary formation, he thought one night, planetesimals becoming planets.

Effectively, your salary has to come straight from the Federation, rather than through a planetary or national formation.

They have nothing directly to do with planetary formation.

Debris disks are thought to constitute a phase in planetary formation.