Distinguish between relative and radiometric dating
Ions can be created, by either chemical or physical means, via ionization. Oxygen is what makes the sky blue, molecules in the air scatter blue light from the sun more than they scatter red light.
And as you got closer, it would almost disappear because of the tremendous amount of space there is between everything, like with atoms.
Galaxy z is 13.1 billion years old, only about 700 million years younger than the universe. That was when the Moon Formed, the Moon was twice as close then it is now causing 10,000 ft. (1.5 Billion Years since the Birth of Earth) - 2.4 billion years ago, oxygen in the atmosphere suddenly increased by about 10,000 times in just 200 million years.
Ocean organisms and primitive animals start to evolve.
A major extinction, the Kellwasser event, occurred at the boundary that marks the beginning of the last phase of the Devonian period, the Famennian faunal stage (the Frasnian–Famennian boundary), about 375–360 million years ago.
Overall, 19% of all families and 50% of all genera became extinct.