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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 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 ...
The theory of panspermia speculates that life on Earth may have come from biological matter carried by space dust [93] or meteorites. [94] While current geochemical evidence dates the origin of life to possibly as early as 4.1 Ga, and fossil evidence shows life at 3.5 Ga, some researchers speculate that life may have started nearly 4.5 billion ...
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.
Oldest known life on Earth. [81] [142] Oort cloud reaches maximum mass. [84] 4.6 billion years Today: Sun remains a main-sequence star. [117] 6 billion years 1.4 billion years in the future Sun's habitable zone moves outside of the Earth's orbit, possibly shifting onto Mars's orbit. [120] 7 billion years 2.4 billion years in the future
Mars Global Surveyor: First image of Earth and the Moon from Mars (in orbit); notice South America is visible. [33] [6] March 11, 2004 Spirit Mars Exploration rover: First image taken of Earth from the surface of Mars and any celestial body other than the Moon. July 27, 2006 Cassini-Huygens: The Pale Blue Orb is the first image of Earth from ...
Although there is abundant geologic evidence for surface water early in Mars history, the nature and timing of the climate conditions under which that water occurred is a subject of vigorous scientific debate. [15] Today Mars is a cold, hyperarid desert with an average atmospheric pressure less than 1% that of Earth.
The exploration of terrestrial analogues provide clues as to how and where best look for signs of life on Mars. [49] Impactite, shown to preserve signs of life on Earth, was discovered on Mars and could contain signs of ancient life, if life ever existed on the planet. [50]