8 seems like some parts were an attempt to reply that would be better as a comment initially for OP to review

# Observations

Observational evidence suggests:

1. Big Bang $$\approx 13.799 Ga$$
2. First Stars $$\approx 13.619 Ga$$
3. First Galaxies $$\approx 13.549 Ga$$
4. First Planets $$\approx 13.000 Ga$$

# Observations

Observational evidence suggests:

1. Big Bang $$\approx 13.799 Ga$$
2. First Stars $$\approx 13.619 Ga$$
3. First Galaxies $$\approx 13.549 Ga$$
4. First Planets $$\approx 13.000 Ga$$

# Observations

Observational evidence suggests:

1. Big Bang $$\approx 13.799 Ga$$
2. First Stars $$\approx 13.619 Ga$$
3. First Galaxies $$\approx 13.549 Ga$$
4. First Planets $$\approx 13.000 Ga$$

# Theory

The structure we see in the Universe has formed from the gravitational collapse of the matter that was once an almost smooth density field of gas ("baryons") and dark matter$$^1$$. The word "almost" is important here, for if it had been completely — or even non-completely but much more — smooth, then the collapse would not have had the time to happen before the expansion of space has diluted the matter enough to prevent any collapse, and we would never had come into existence.

Gravitational collapse

First clumps

## First clumps

Stars, galaxies, and clusters

Dust

Planets

## Planets

Thus, we can make the following timeline:

# Timeline

Minihalos → gas clouds → stars → galaxies → stardust → planets. We can make the following timeline:

1. Minihalos
2. Gas clouds
3. Stars
4. Galaxies
5. Stardust
6. Planets

The structure we see in the Universe has formed from the gravitational collapse of the matter that was once an almost smooth density field of gas ("baryons") and dark matter$$^1$$. The word "almost" is important here, for if it had been completely — or even non-completely but much more — smooth, then the collapse would not have had the time to happen before the expansion of space has diluted the matter enough to prevent any collapse, and we would never had come into existence.

Gravitational collapse
First clumps
Stars, galaxies, and clusters
Dust
Planets

Thus, we can make the following timeline:

Minihalos → gas clouds → stars → galaxies → stardust → planets.

# Observations

Observational evidence suggests:

1. Big Bang $$\approx 13.799 Ga$$
2. First Stars $$\approx 13.619 Ga$$
3. First Galaxies $$\approx 13.549 Ga$$
4. First Planets $$\approx 13.000 Ga$$

# Theory

The structure we see in the Universe has formed from the gravitational collapse of the matter that was once an almost smooth density field of gas ("baryons") and dark matter$$^1$$. The word "almost" is important here, for if it had been completely — or even non-completely but much more — smooth, then the collapse would not have had the time to happen before the expansion of space has diluted the matter enough to prevent any collapse, and we would never had come into existence.

# Timeline

We can make the following timeline:

1. Minihalos
2. Gas clouds
3. Stars
4. Galaxies
5. Stardust
6. Planets
6 replaced http://astronomy.stackexchange.com/ with https://astronomy.stackexchange.com/

Stars consist of collapsed gas and almost no dark matter, and the formation of a star thus needs the theory of hydrodynamics rather than just gravity. In order for matter to collapse to such dense structures as stars, it must get rid of much of its energy. This is not possible for the collisionless dark matter (at least in the normal sense, but this postthis post), but gas, which can collide and cool by radiating, is able to do so$$^3$$.

Stars consist of collapsed gas and almost no dark matter, and the formation of a star thus needs the theory of hydrodynamics rather than just gravity. In order for matter to collapse to such dense structures as stars, it must get rid of much of its energy. This is not possible for the collisionless dark matter (at least in the normal sense, but this post), but gas, which can collide and cool by radiating, is able to do so$$^3$$.

Stars consist of collapsed gas and almost no dark matter, and the formation of a star thus needs the theory of hydrodynamics rather than just gravity. In order for matter to collapse to such dense structures as stars, it must get rid of much of its energy. This is not possible for the collisionless dark matter (at least in the normal sense, but this post), but gas, which can collide and cool by radiating, is able to do so$$^3$$.