Video Transcript
The diagram shows the first part of
how the solar system formed. Which word would replace the
blank?
We know that the solar system began
as a large cloud of gas and dust in space several billion years ago. All of the gas and dust particles
were attracted towards each other due to gravity, and so the cloud contracted. This made the gas and dust
particles move faster and faster. And the particles collided with
each other more often. Thus, the temperature of the cloud
increased, and it started emitting light.
Now, this next step is where we can
start to think about how to fill in the blank. The cloud was rotating faster
because it was contracting. And this rotation caused the cloud
to flatten out. We would be wrong to think that the
gas cloud spun into a spherical shape, like a ball. In reality, spinning an object has
a tendency to pull and flatten it outward from its center. This is why pizza makers throw and
spin their pizza dough in the air. The pizza dough may start out as a
ball, but rotating it helps the dough flatten out into a disc shape. Funny enough, the same sort of
concept applies to the formation of pizza dough and the formation of the solar
system. This is why the cloud formed a disk
shape instead of a sphere.
Filling in the blank, we know that
as the cloud of gas and dust continues to contract and heat up, it starts to form a
rotating disk.
