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Zprotu t1_itod3zu wrote

Reply to comment by OrokaSempai in A Nearby Star Has Completely Blasted Away the Atmosphere From its Planet by Tao_Dragon

Question. We know the earth is 4.543B years old, but what exactly does this number mean? Technically, wouldn't the creation process of the earth have started right at the moment of the solar system's beginning? (i.e the exact second of the gravitational collapse of the giant interstellar molecular cloud, so 4.6B years ago, adding about 400M years to the age)

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OrokaSempai t1_itpn6iy wrote

At some point 2 grains of sand stuck together that would eventually become the earth, but is that actually the earth? Before the moon was formed in an impact with another proto-planet, it was not the same size or composition as today, so at that point it was also a proto planet. That impact was the final step to those proto planets becoming the Earth and Moon, so personally I would say the earth is 4.5B years old, the point it became its final mass. (Also, the cores of the 2 proto planets would have combined at that point giving the earth a large core and powerful magnetic field).

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Zprotu t1_itubxzx wrote

Well all that is definitely included in the creation process of the earth to what it is today. Its why I would consider the point in time when the 2 grains of sand got stuck together as the start of the earth. We are talking about the beginning of earth's creation process after all. And this process began exactly at the moment of the gravitational collapse of the interstellar molecular cloud, no? Wouldn't thinking that the earth is 4.6B years old be correct if you frame it like that?

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