When.com Web Search

Search results

  1. Results From The WOW.Com Content Network
  2. Evolution of photosynthesis - Wikipedia

    en.wikipedia.org/wiki/Evolution_of_photosynthesis

    4.6 billion years ago Earth forms 3.4 billion years ago First photosynthetic bacteria appear 2.7 billion years ago Cyanobacteria become the first oxygen producers 2.4 – 2.3 billion years ago Earliest evidence (from rocks) that oxygen was in the atmosphere 1.2 billion years ago Red and brown algae become structurally more complex than bacteria ...

  3. Age of Earth - Wikipedia

    en.wikipedia.org/wiki/Age_of_Earth

    The meteorite samples, however, show a spread from 4.53 to 4.58 billion years ago. This is interpreted as the duration of formation of the solar nebula and its collapse into the solar disk to form the Sun and the planets.

  4. Earliest known life forms - Wikipedia

    en.wikipedia.org/wiki/Earliest_known_life_forms

    Earth is the only place in the universe known to harbor life, where it exists in multiple environments. [8] [9] The origin of life on Earth was at least 3.5 billion years ago, possibly as early as 3.8-4.1 billion years ago. [2] [3] [4] Since its emergence, life has persisted in

  5. Paleoarchean - Wikipedia

    en.wikipedia.org/wiki/Paleoarchean

    It was created around 3.26 Ga when a large asteroid, about 37 to 58 kilometres (23–36 mi) wide, collided with the Earth. [6] The Buck Reef chert and the Josefsdal chert, two rock formations in the Barberton Greenstone Belt, both contain microbial mats with fossilized bacteria from the Paleoarchean era. [ 4 ]

  6. Geologic time scale - Wikipedia

    en.wikipedia.org/wiki/Geologic_time_scale

    The geologic time scale is a way of representing deep time based on events that have occurred throughout Earth's history, a time span of about 4.54 ± 0.05 Ga (4.54 billion years). [3] It chronologically organises strata, and subsequently time, by observing fundamental changes in stratigraphy that correspond to major geological or ...

  7. Purple Earth hypothesis - Wikipedia

    en.wikipedia.org/wiki/Purple_Earth_hypothesis

    [2] [3] It is estimated to have occurred between 3.5 and 2.4 billion years ago during the Archean eon, prior to the Great Oxygenation Event and Huronian glaciation. [ 4 ] Retinal-containing cell membranes exhibit a single light absorption peak centered in the energy-rich green-yellow region of the visible spectrum , but transmit and reflect red ...

  8. History of life - Wikipedia

    en.wikipedia.org/wiki/History_of_life

    The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...

  9. Timeline of the far future - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_the_far_future

    This is an accepted version of this page This is the latest accepted revision, reviewed on 31 January 2025. Scientific projections regarding the far future Several terms redirect here. For other uses, see List of numbers and List of years. Artist's concept of the Earth 5–7.5 billion years from now, when the Sun has become a red giant While the future cannot be predicted with certainty ...