Which theory explains that planets formed from condensing of solar nebulae?

• A. Solar Nebulae Theory
• B. Nebular Theory
• C. Planetary Accretion Theory
• D. Geocentric Theory

Answer: (A)

Planets form from the material in a solar nebula that condenses and aggregates. This idea is described by the Nebular Theory, which envisions a rotating cloud of gas and dust that collapses under gravity, forms a disk, and allows dust grains to collide and stick together, growing into larger bodies called planetesimals and eventually planets. Emphasizing the starting material, Solar Nebula Theory is an equivalent label for this idea. The term Nebular Theory is the standard name for the model. A related idea, Planetary Accretion Theory, refers to the growth mechanism within the nebula but isn’t the common name for the entire model. Geocentric Theory describes an Earth-centered universe and does not describe how planets formed from nebulae.