Editing Hadean Eon (section)

== Formation of the Sun ==
As the cloud collapsed under its own gravity to form the Sun and the solar system, it conserved its '''angular momentum'''. Angular momentum is a physical quantity that measures the amount of rotation of an object, and it is conserved in a system unless acted upon by an external '''torque'''. Since there's no external force to provide such a torque in the vacuum of space, the collapsing cloud's rotation speed increased as it shrank in size, much like a figure-skater spins faster when pulling in their arms.

'''L = Iω''', where:

* I is the moment of inertia (a measure of an object's resistance to changes in its rotation rate), and
* ω is the angular velocity (the rate of rotation). The moment of inertia is dependent on the mass distribution relative to the axis of rotation; for a given mass, spreading it further from the rotation axis increases.

The cloud's radius decreases, significantly reducing its moment of inertia (I) by I=mr<sup>2</sup>. According to the conservation of angular momentum, if I decreases and L is conserved, then ω (angular velocity) must increase. This means the cloud spins faster as it collapses.

The outcome of this conservation is that as the molecular cloud that became the solar system collapsed, it spun faster, leading to the formation of a rotating protostar - the young Sun. Over time, the Sun reached its current rotation period, which is about 25 days at the equator and longer at higher latitudes, due to its gaseous nature allowing for differential rotation. Over time, the distribution of the Sun's mass and interactions between its magnetic field and the solar wind (a stream of charged particles emitted by the Sun) have likely influenced its rotation rate, a process known as magnetic braking. This process can gradually slow down the rotation rate of stars, including the Sun.