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.
However, Dr. Thomas explained to the press in May 2013 that the ring arcs are much more tenuous than the fully formed rings of Saturn. As a matter of fact, the ring arcs are so delicate and thin that it would take about ten billion years for just 1 meter of blowing icy snow to collect within the craters of Methone.
Although the provisional designation of 2005 FY9 was given to Makemake when its discovery was made public, before that Dr. Brown's team had used the playful codename "Easter Bunny" for this small world, because of its discovery shortly after Easter.
Therefore, even though Enceladus is only Saturn's sixth-largest moon, it is amazingly active. Because of the success of the Cassini mission, scientists now know that geysers spew watery jets hundreds of kilometers out into Space, originating from what may well be a vast subsurface sea. These jets, which erupt from fissures in the little moon's icy shell, whisper a siren's song to bewitched astronomers. This is because the jets suggest that the icy moon may harbor a zone where life might have evolved. The jets dramatically spray water ice from numerous fissures near the south pole, that have been playfully termed "tiger stripes." The "tiger stripes" look like giant scratches made by a tiger's raking claws.