Search results
Results from the WOW.Com Content Network
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
The Moon formed soon afterwards, possibly as a result of the impact of a large planetoid with the Earth. [12] [13] More recent potassium isotopic studies suggest that the Moon was formed by a smaller, high-energy, high-angular-momentum giant impact cleaving off a significant portion of the Earth. [14]
Momentum depends on the frame of reference, but in any inertial frame it is a conserved quantity, meaning that if a closed system is not affected by external forces, its total momentum does not change. Momentum is also conserved in special relativity (with a modified formula) and, in a modified form, in electrodynamics, quantum mechanics ...
The process of accretion, therefore, is not complete, and may still pose a threat to life on Earth. [ 82 ] [ 83 ] Over the course of the Solar System's evolution, comets were ejected out of the inner Solar System by the gravity of the giant planets and sent thousands of AU outward to form the Oort cloud , a spherical outer swarm of cometary ...
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth itself.
Earth's atmosphere contains 78% nitrogen and 21% oxygen, which is the result of the presence of life. [103] [104] The planet has a complex climate and weather system, with conditions differing drastically between climate regions. [105] The solid surface of Earth is dominated by green vegetation, deserts and white ice sheets.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
The Gaia hypothesis (/ ˈ ɡ aɪ. ə /), also known as the Gaia theory, Gaia paradigm, or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating complex system that helps to maintain and perpetuate the conditions for life on the planet.