Rocky cores form first

Newly discovered superEarth systems support the standard model of planet formation

NANTES, France — Call it the battle of the planet creationists.

PLANETARY BEGINNINGS This artist’s illustration shows a swirling protoplanetary disk in which core accretion could happen. P. Rawlings, NASA

On one side of the ring stands Doug “Rocky Core” Lin. On the other side stands Alan “Jupiter in a Hurry” Boss.