Protoplanetary Disk Clumps of solid material begin to solidify as they accumulate enough mass; growing larger as the result of collisions. Eventually, a few large objects -- protoplanets -- will begin to dominate the nebula, accreting more and more of the nebular material as the amount of free dust and gas is steadily reduced.
Visual Timeline of the Universe
From Nick Greene, former About.com Guide
Planetesimals Form and Protoplanets Condense
Artist's Concept of a Protoplanetary Disk - Within the spinning protoplanetary disk, gravity allows clumps to form and grow - - creating objects called planetesimals.
NASA
Within the spinning protoplanetary disk, gravity allows clumps to form and grow -- creating objects called planetesimals. Heavy metals and silicates can survive the winds and high temperatures found close to the star, but lighter, volatile materials such as water and hydrogen gas survive only in the outer parts of the disks.
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- The Big Bang
- Galaxies
- Giant Molecular Clouds
- Clouds and Star Birth
- Mature Stars and Nucleosynthesis
- Star Death and the Distribution of Elements for New Star Systems
- Protoplanetary Disks
- Planetesimals Form and Protoplanets Condense
- Forming Jupiter- and Earth-Like Planets
- Chemistry of Life
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