What process heated the early solar nebula as it slowly condensed toward a central protosun?
A) the radioactive decay of heavy elements originally formed in the Big Bang
B) the release of heat as molecules formed and gases condensed into ices
C) thermonuclear fusion in the protosun, followed by radiative heating of the nebula
D) the release of heat by collisions of particles as they gained kinetic energy in falling toward the center of the nebula

Question

Quizplus · Accepted Answer

As particles fell towards the center of the nebula, they gained kinetic energy and collided, releasing heat energy. This process is known as gravitational contraction and it caused the nebula to heat up, eventually leading to the formation of the protosun. Option A is incorrect because the radioactive decay of heavy elements formed in the Big Bang would not have been sufficient to heat up the nebula. Option B is also incorrect because the formation of molecules and condensation of gases would have actually led to a cooling effect. Option C is incorrect because thermonuclear fusion did not start until the protosun had formed.

What Process Heated the Early Solar Nebula as It Slowly