Within the first billion years of Earth’s history, life appeared in the oceans and began to affect the Earth’s atmosphere and surface, leading to the proliferation of anaerobic and, later, aerobic organisms. Some geological evidence indicates that life may have arisen as early as 4. 1 billion years ago. Since then, the combination of Earth’s distance from the Sun, physical properties and geological history have allowed life to evolve and thrive. In the history of life on Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that ever lived on Earth are extinct. Estimates of the number of species on Earth today vary widely; most species have not been described. Over 7. 7 billion humans live on Earth and depend on its biosphere and natural resources for their survival. Humans have developed diverse societies and cultures; politically, the world has around 200 sovereign states.
Christian folklore claims the Man in the Moon is Cain, the eternal Wanderer, doomed forever to circle the Earth. In addition, there is a Talmudic tradition that says it is the face of Jacob etched out on the gleaming lunar disk.
The astronomers found that larger craters, which excavated pits much deeper into the Moon's surface, only increased porosity in the underlying crust. This indicates that these deeper layers have not reached a steady state in porosity, and are not as fractured as the megaregolith.
On March 27, 2012, Cassini made its closest flyby yet over Enceladus's "tiger stripes". In a string of enticingly close passes over the dazzling moon, the spacecraft saw more hints that watery jets may be shooting out into Space from an immense subsurface sea. The jets, tearing through cracks in the moon's icy crust, could lead back to a zone harboring living tidbits.