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Little is known of what people thought about comets before Aristotle, who observed his eponymous comet, and most of what is known comes secondhand.From cuneiform astronomical tablets, and works by Aristotle, Diodorus Siculus, Seneca, and one attributed to Plutarch but now thought to be Aetius, it is observed that ancient philosophers divided themselves into two main camps.
[66] [69] Comets may also have contributed. Though most comets are today in orbits farther away from the Sun than Neptune, computer simulations show that they were originally far more common in the inner parts of the Solar System. [59]: 130–132 As Earth cooled, clouds formed. Rain created the oceans.
The origin of water on Earth is the subject of a body of research in the fields of planetary science, astronomy, and astrobiology. Earth is unique among the rocky planets in the Solar System in having oceans of liquid water on its surface. [2]
Comets whose aphelia are near a major planet's orbit are called its "family". [81] Such families are thought to arise from the planet capturing formerly long-period comets into shorter orbits. [82] At the shorter orbital period extreme, Encke's Comet has an orbit that does not reach the orbit of Jupiter, and is known as an Encke-type comet.
The geological history of Earth follows the major geological events in Earth's past based ... augmented by ice delivered from comets, produced the oceans. [15 ...
In the early history of the Earth (about four billion years ago), bolide impacts were almost certainly common since the Solar System contained far more discrete bodies than at present. Such impacts could have included strikes by asteroids hundreds of kilometers in diameter, with explosions so powerful that they vaporized all the Earth's oceans.
The Winchcombe meteorite could also hold clues about where the water in the Earth’s vast oceans came from. ... group at the Natural History Museum, said 12% of the sample was made up of water ...
The abundance of deuterium in comet Hale–Bopp in the form of heavy water was found to be about twice that of Earth's oceans. If Hale–Bopp's deuterium abundance is typical of all comets, this implies that although cometary impacts are thought to be the source of a significant amount of the water on Earth, they cannot be the only source. [48]