Dating systems history
Hubble drew upon existing ideas and evidence to demonstrate that the Universe was much larger than previously thought and proved that it is expanding — laying the foundations for the Big Bang theory. In one second it races around the Earth seven times. Going out to the stars, Astronomers know that by studying Cepheid variables, the fluctuation in brightness of certain stars, we can calculate the star's distance from Earth.The longer the period of fluctuation, the brighter the star.And four years to reach Proxima Centauri, the next nearest star. Early microbes, in their struggle for life, clashed with and consumed hydrogen gas. These microbes evolved into prokaryotes and adapted further, finding energy in sunlight.Then, in a process called photosynthesis, they flooded the atmosphere with oxygen.
Some life forms survived, some proliferated, pushing oxygen levels higher. Combining "bio," meaning life, and "sphere," referencing the Earth's rounded surface, English-Austrian Geologist Eduard Suess coins the term that expressed the portion of the Earth that supports life.
Ever since the Big Bang, the Universe has been drifting and expanding.
The birth and death of stars leave an aftermath of galaxies, planets, and even living organisms.
Earth was at a center of a series of concentric spheres containing the Moon, the planets, the Sun, and a final sphere of fixed stars.
By measuring the amount of time between the fluctuating brightness levels of variable stars, Leavitt discovered that it would be possible to estimate their distance away from the Earth, and possible to map the Universe.