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The thermosphere (or the upper atmosphere) is the height region above 85 kilometres (53 mi), while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near an altitude of 45 kilometres (28 mi) and causes the ozone layer.
The chronology of the universe describes the history and future of the universe according to Big Bang cosmology. Research published in 2015 estimates the earliest stages of the universe's existence as taking place 13.8 billion years ago, with an uncertainty of around 21 million years at the 68% confidence level. [1]
Date Mission achievements Country/organization Mission name Ref(s). 4 October 1957: First artificial satellite. First human-made signals from space. USSR Sputnik 1: 3 November 1957: First mammal in orbit, the dog Laika. USSR Sputnik 2: 31 January 1958: Confirmed existence of the Van Allen radiation belt. USA Explorer 1: 17 March 1958
The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments of imaging, observation, and publication differ), identified through its various designations (including temporary and permanent schemes), and the ...
c. 16th century BCE – Mesopotamian cosmology has a flat, circular Earth enclosed in a cosmic ocean. [1]c. 15th–11th century BCE – The Rigveda of Hinduism has some cosmological hymns, particularly in the late book 10, notably the Nasadiya Sukta which describes the origin of the universe, originating from the monistic Hiranyagarbha or "Golden Egg".
The first reasonably accurate measurement of the rate of expansion of the universe, a numerical value now known as the Hubble constant, was made in 1958 by astronomer Allan Sandage. [8] His measured value for the Hubble constant came very close to the value range generally accepted today.
The timeline of the Universe lists events from its creation to its ultimate final state. For a timeline of the universe from the present to its presumed conclusion, see: Timeline of the far future Chronology of the universe
The map shows "ripples", caused by slight variations in the density of the early universe – the seeds of galaxies and galaxy clusters. The 10-meter Keck telescope on Mauna Kea, Hawaii, is completed. The first revolutionary new wave of telescopes, the Keck's main mirror is made of 36 six-sided segments, with computers to control their alignment.