Timeline of the Universe

The first stars were born when the universe was around 100 million years old and were made entirely of hydrogen and helium, which made heavier elements in their core. As for galaxies, they formed all over for the first 1–2 billion years of the universe, all of which eventually led to the Milky Way galaxy, our solar system, Earth, and us. The solar system formed around 4.5 billion years ago from an interstellar cloud of gas and dust, due to gravity and a nearby star going supernova, from which we got the elements required for life as we know it. When the dust collapses, it forms what we call a “Solar Nebula,” which is a spinning disk of material. Because of gravity, more and more material started falling into the center of the disc, which eventually led the hydrogen atoms to fuse into helium because of the immense pressure. The leftovers that didn’t end up at the center collapsed into each other, making larger and larger objects, which became planets, large moons, and dwarf planets. Smaller pieces became smaller moons, asteroids, meteoroids, and comets. The first four planets, which are Mercury, Venus, Earth, and Mars, are all rocky planets, since they could withstand the heat from the sun when the solar system was first born. The other planets, Jupiter, Saturn, Uranus, and Neptune. Jupiter and Saturn being gas giants, and Uranus and Neptune being ice giants. <a href="https://medium.com/@particle.science7/timeline-of-the-universe-5e2418e05e2c">Read More</a>