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Outer space does not begin at a definite altitude above Earth's surface. The Kármán line , an altitude of 100 km (62 mi) above sea level , [ 9 ] [ 10 ] is conventionally used as the start of outer space in space treaties and for aerospace records keeping.
Earth's atmosphere photographed from the International Space Station.The orange and green line of airglow is at roughly the altitude of the Kármán line. [1]The Kármán line (or von Kármán line / v ɒ n ˈ k ɑːr m ɑː n /) [2] is a conventional definition of the edge of space; it is widely but not universally accepted.
The recombination epoch begins at around 18,000 years, as electrons are combining with helium nuclei to form He +. At around 47,000 years, [4] as the universe cools, its behavior begins to be dominated by matter rather than radiation. At around 100,000 years, after the neutral helium atoms form, helium hydride is the first molecule.
c. 10 −36 seconds: Electroweak epoch begins: The Universe cools down to 10 28 kelvin. The strong nuclear force becomes distinct from the electroweak force.; c. 10 −33 seconds: Space is subjected to inflation, expanding by a factor of the order of 10 26 over a time of the order of 10 −33 to 10 −32 seconds.
First space walk/extra-vehicular activity (Alexei Leonov). USSR Voskhod 2: March 1965: First crewed spacecraft to change orbit. USA (NASA) Gemini 3: 14 July 1965: First flyby of Mars (returned pictures). USA (NASA) Mariner 4 [18] 14 July 1965: First photographs of another planet from deep space . USA (NASA) Mariner 4 [18] 26 November 1965
The Space Age is a period encompassing the activities related to the space race, space exploration, space technology, and the cultural developments influenced by these events, beginning with the launch of Sputnik 1 on October 4, 1957, [1] and continuing to the present.
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Life begins on Earth: 15.555 gal 3500 Ma: Prokaryotes appear 12 gal 2700 Ma: Bacteria appear 10 gal 2250 Ma: Eukaryian period [5] [6] first appearance of eukaryotes [7] Stable continents appear 6.8 gal 1530 Ma: Multicellular organisms appear 2.4 gal 540 Ma: Cambrian explosion occurs 2 gal 500 Ma: The first brain structure appears in worms 1.11 ...