Video Transcript
Which of the following diagrams
correctly shows how the solar system formed?
This question is asking us to
recall the stages of the solar system’s formation. First, let’s recall that the solar
system formed from what was once a large cloud of dust and gas in space. All three answer choices begin with
this assumption, so we can’t rule any out at this stage.
Next, recall that the effect of
gravity, which is the attractive force between objects that have mass, caused the
cloud to contract. This means that the dust and gas
particles moved closer together and the whole cloud got smaller and denser. This is correctly described in
options (B) and (C). Therefore, we can eliminate option
(A). Option (A) does not show gravity
causing the whole cloud to contract and get smaller, so (A) cannot be correct.
If we consider options (B) and (C),
we see that the next step is the same for both options. The cloud of gas and dust contracts
and it heats up, emitting light. However, after this stage, option
(B) misses a crucial part of the process. Option (B) fails to say that the
cloud of dust and gas formed a rotating disk. So option (B) cannot be the correct
answer.
It is important to remember that
the cloud formed a rotating disk, because this disk was crucial for the formation of
the Sun and the planets. Once the rotating disk became hot
enough and dense enough, the Sun formed at the center of the disk. The planets formed from the
material in the outer disk. This is correctly described by
option (C).
Even if we couldn’t remember that
the solar system once formed a rotating disk, the final step in option (B) tells us
that (B) cannot be the correct answer. As far as scientists know, planets
do not get captured from other solar systems, as stars are usually too far apart for
this to be possible. Once a planet is formed in a
particular solar system, it stays there. This means that option (C) is the
only option that correctly describes the formation of the solar system. (C) must be the correct answer.
