At what point in time is it said that the protosun became the Sun?
A) when thermonuclear fusion reactions began at its center
B) when it became hot enough to emit light and heat
C) when the temperature began to rise at its center
D) when planetary formation was complete

Question

Quizplus · Accepted Answer

The protosun transitioned into the Sun when thermonuclear fusion reactions began at its center, marking the start of the Sun's main sequence phase. This is a defining moment that differentiates a protostar from a main-sequence star like the Sun.

At What Point in Time Is It Said That the Protosun