Final answer:
The two theorized sources of the origin of life on Earth are earthly and extraterrestrial sources. Earthly sources suggest that organic molecules could have formed on Earth under certain conditions, while extraterrestrial sources propose that life originated elsewhere and was seeded onto Earth. The exact origin of life on Earth, however, is still unknown.
Step-by-step explanation:
There are two main theorized sources of the origin of life on Earth: earthly and extraterrestrial sources. The earthly sources suggest that organic molecules, including amino acids, could have formed under certain conditions on Earth, such as inorganic molecules and energy present in the early conditions of the planet. This was supported by laboratory experiments conducted by scientists Stanley Miller and Harold Urey. On the other hand, the extraterrestrial sources propose that life itself originated elsewhere and was seeded onto Earth, possibly through objects like meteoroids and asteroids carrying organic compounds and microorganisms. Although there is more direct evidence for the extraterrestrial sources, the exact origin of life on Earth remains a mystery.