The evo­lu­tion of astrom­e­try

Dis­cover how we’ve been chart­ing the skies for over 2,000 years

How It Works - - SPACE -

Astrom­e­try is a branch of as­tron­omy con­cerned with map­ping the sky. Records show that it is one of the first sci­ences and was prac­tised by sev­eral early civil­i­sa­tions. Mon­i­tor­ing the move­ments of stars and plan­ets served a prac­ti­cal pur­pose for an­cient cul­tures, from track­ing time to aid­ing nav­i­ga­tion and tim­ing rit­u­als .

The first astronomers could track vis­i­ble ce­les­tial bod­ies and record their pe­ri­odic mo­tions, but it wasn’t un­til the third cen­tury BCE that at­tempts were made to es­ti­mate their dis­tances us­ing ge­om­e­try.

The invention of the te­le­scope in the 17th cen­tury led to an as­tron­omy revo­lu­tion. With an en­hanced view of the uni­verse, astronomers could col­lect more ev­i­dence to sup­port the he­lio­cen­tric model — the idea that the Sun, not the Earth, was at the cen­tre of our So­lar Sys­tem. The te­le­scope en­abled much more de­tailed cat­a­logu­ing of stars’ po­si­tions and dis­tances.

The 19th and 20th cen­turies saw the de­vel­op­ment of more ad­vanced tele­scopes, as well as pho­tog­ra­phy, which im­proved the ac­cu­racy and de­tail of star charts. But Earth’s at­mos­phere in­ter­feres with mea­sure­ments from the ground as it makes stars ap­pear to flicker. Since the ad­vent of the space age in the 1950s, we have been able to launch tele­scopes into or­bit, over­com­ing at­mo­spheric in­ter­fer­ence to see fur­ther into the cos­mos than ever be­fore.

ESA’S lat­est mis­sion to chart the skies will rely on the space te­le­scope Gaia, which is cur­rently map­ping the po­si­tion, par­al­lax and an­nual proper mo­tion of about 1 bil­lion stars. This will pro­vide us with a three-di­men­sional map of our galaxy in un­prece­dented de­tail, as well as a new, de­fin­i­tive stel­lar cat­a­logue, due to be pub­lished in the early 2020s.

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