A reference to the motion of accretion disks, this engraving emerged from my interest in how these accretion disks eventually evolve to form rocks, planets, and ultimately living beings and people.
Proto-planetary disks are accretion disks that feed a central star. Initially very hot, the disk eventually cools. Here, formation of small dust grains made of rocks and ice are possible. The grains eventually may coagulate into kilometer-sized planetesimals. If the disk is massive enough, the runaway accretions begin, resulting in rapid—100,000 to 300,000 years—formation of Moon- to Mars-sized planetary embryos. Near the star, the planetary embryos go through a stage of violent mergers, producing a few terrestrial planets. The last stage takes approximately 100 million to a billion years.