David Bercovici’s lecture on the origins of the Earth was pretty science orientated to me. Before his lecture and seminar, we read few chapters of his book the Origins of Everything in 100 Pages (More or Less), in which Bercovici introduced the formation of the solar system, the planet Earth, the ocean, and the climate. I learned from his book and lecture about the chemical and geological processes that all these basic building blocks went through to form the environment we live in today. But jumping out of the pure science cycle, it is also interesting to think about the social and historian implications of these scientific findings.
On August 21 2017, people all around the world especially those here in the United States were excited to see one event after an interval of nearly a century ー a total eclipse of the Sun. This is the phenomena that the Moon covers the Sun when it is passing between the Sun and the Earth and casts darkness on the Earth. Though now it is ordinary for us to see the Sun and the Moon in the sky everyday, have we ever thought about how were those planets, including our planet Earth, were created by taking many years to be formed like we know now?
The Moon is 1/400 the size of the Sun and 1/4 the size of the Earth. It is the only satellite which goes around the Earth. I did not consider the existence of Moon deeply until Bercovici mentioned in the lecture that our Moon is weird and not a typical planet compared with a lot of moons around planets in terms of composition because the lunar mantle is very low in elements.
The origin of the Moon goes back to as same period as the Earth. There is one hypothesis to explain how the Moon was created. The giant-impact hypothesis ways that the Moon was formed by a catastrophic collision and its debris and gas consolidated. Since the Moon and the Earth have been attracting each other. Because the Moon was born in almost same period as the Earth, I feel the Moon is the Earth’s sibling. It also reminded me the Apollo program from 1969 to 1972, which was one of the biggest events in human history. It revealed many new findings about the Moon, although how it was created is covered in mystery. But still I believe that knowing about the Moon leads us to new discovery of the origin of the Earth and the stars.
What would happen if the Sun and the Moon vanish? If the Sun suddenly disappeared, all the planets surrounding the Sun would retain their forward motion, and they would fly off. The planets would start getting colder and colder and no life could survive under this circumstance. If there were no moon passing around our planet, the Earth would spin faster and the length of the day would shorten to ⅓ than now. The environment, needless to say, would dramatically change and many species would be endangered. Earth’s axis, which is inclined at about 23.4 degrees by the Moon would vary over time and we would not have seasons through a year anymore.
Considering the origin of not only the Earth but also the stars allow me to feel every single event that happened in the universe starting from the Big Bang were indispensable. The Earth has been coexisting with those stars and we are still keeping this relationship in a dynamic scale. Now every time I look up at the sky and see the Sun and the Moon, I feel that they are both important components of the Earth as it is now.
From David Bercovici’s lecture, it is clear that Earth is not an ordinary planet. It is the only planet that mankind knows of that can support intelligent life. Earth is the only terrestrial planet with water and a habitable climate. The chance of having life itself in a planet is extremely low numerous dynamic variables play into when looking at life on other planets. The specific conditions that are required for a planet to support life and to become habitable are impressive, and it allows people to understand how slim the probability was for origins of mankind to have started on Earth.
Bercovici first explains how our universe started from the Big Bang and how our solar system was created. The planetary clouds collapsed and formed stars. Our star, the sun, is also unique in a sense that since it is a small star. All stars use hydrogen fusion to use energy, and since our sun is a small star, it burns longer than other giant stars. These giant stars undergo hydrogen fusion but when it runs out of elements to burn through it goes into Supernova. This explosion of the star leaves all the elements that makeup in the world. Elements like carbon, oxygen, nitrogen, phosphate, magnesium, iron, silicon, etc.… all these elements are building blocks of life and helped create Earth.
Earth, when compared to other terrestrial planets in our solar system, like Venus and Mars is the only planet that has habitable climate and water. These two features are essential for life, and so far we have not found any planets with a habitable climate, but some planets and moons that have had water in the past solid and liquid. Earth is also unique because it has plate tectonics which other planets do not have. Earth uses plate tectonics to regulate its climate. The two planets most like Earth is Venus and Mars, Venus is too hot for life to exist and Mars is too cold for life to exist. Earth has just the right temperature for life to exist.
If we want to look at life and where it came from and how other planets can support life, we should look no other planet than Earth, and for the time being, Earth is the only planet that we know of that can support life. However, the probability of having all the right conditions for a habitable planet to exist is so low it makes us wonder if our origin was just dumb luck or are their other planets out in the universe with the same or similar conditions that have intelligent life.
The unlikeliness of mankind to exist should give a different perspective of origins of our universe. Beating the odds to have existed as a human on Earth should be looked as being very fortunate. Origins of Earth helps us understand how we came to be as mankind and should be viewed as a flexible guiding blueprint in search of other life in other habitable planets and how other origins are formed to be in the future.