Visual Timeline of the Universe

Protoplanetary Disks

Circumstellar Debris Disk - Forming planetary systems may appear as dark or luminous disks silhouetted against a glowing nebula.

NASA, ESA, and P. Kalas (University of California, Berkeley)

These protoplanetary regions are up to 20 times the diameters of our solar system. All the material in a protoplanetary disk spins in the same direction around the star. The disk includes the complex molecules found in the original nebula, plus others that may form as the density and temperature change in the dense regions of the nebula surrounding the star.

• 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