what guided the sailors at sea in olden times
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Sun, Stars, Moon to find the right direction
navigation requires the sailor to use an instrument, like a sextant, to find the angle between a star/planet and the horizon. The angle will tell the sailor is latitude. ... The astrolabe dates back to ancient Greece, when it was used by astronomers and mariners to help tell time and location.
navigation requires the sailor to use an instrument, like a sextant, to find the angle between a star/planet and the horizon. The angle will tell the sailor is latitude. ... The astrolabe dates back to ancient Greece, when it was used by astronomers and mariners to help tell time and location.
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How$did$sailors$of$centuries$past$find$their$way$
across$the$seas$
before$the$
invention$of$the$
compass$and$the$
sextant?$$The$
earliest$sailors$
followed$the$
coastline$as$far$as$
they$could,$using$
features$on$land$to$
mark$their$
location.$$But$
when$their$
journey$took$
them$far$from$
land,$they$relied$
on$the$sky.
Early$sailors$knew$that$the$Sun$rises$in$the$east$
and$sets$in$the$west,$and$they$used$that$knowledge$
to$guide$them.$$So$if$they$sailed$into$the$rising$Sun,$
they$knew$they$were$heading$east.$$If$they$turned$
to$the$right,$putting$the$rising$Sun$on$their$left$
side,$they$knew$that$they$were$heading$south.$
At$night,$these$ancient$mariners$steered$by$the$
stars.$$The$North$Star$proved$a$stable$marker$in$
the$Northern$Hemisphere$because$Earth’s$
northern$axis$points$to$the$North$Celestial$Pole$
(celestial$means$“dealing$with$the$sky;$heavenly”).$$
The$North$Star,$Polaris,$is$the$star$currently$closest$
to$the$North$Celestial$Pole.$$As$Earth$rotates$on$its$
axis,$the$stars$in$the$night$sky$seem$to$move$in$a$
circle,$because$they$are$fixed$relative$to$Earth.$$But$
the$North$Star$remains$in$one$spot$in$the$Northern$
Hemisphere$sky$at$all$times,$and$all$the$other$stars$
seem$to$rotate$around$it.$$The$farther$north$a$sailor$
traveled$in$the$Northern$Hemisphere,$the$higher$
the$North$Star$appeared$in$the$sky.$$The$farther$
south$one$sailed$in$the$Northern$Hemisphere,$the$
lower$the$star$appeared$in$the$sky.$$
Many$sailors$of$old$used$a$handy$tool$to$help$
measure$precisely$how$high$or$low$a$star$was$in$
the$sky:$their$fingers!$$By$holding$his$arms$straight$
out$in$front$of$him,$a$mariner$laid$his$fingers$on$
top$of$each$other$to$measure$the$“height”$of$a$star$
such$as$the$North$Star$from$the$horizon.$$Because$
the$height$of$Polaris$above$the$horizon$is$equal$to$
the$latitude$at$a$particular$location,$sailors$could$
use$the$star$to$estimate$their$location.$$They$
would,$for$example,$turn$west$or$east$once$a$
particular$star$selected$for$navigation$was$two$
fingerRwidths$above$the$horizon.$$Very$clever!$$
Although$the$skies$are$still$important$in$
guiding$ships,$today’s$sailors$use$computer$and$
satellite$technology$– such$as$the$Global$
Positioning$System$(GPS)$– to$guide$their$travels.$$
Navigators$have$come$a$long$way$since$the$days$of$
steering$by$the$stars.
Constant$as$the$North$Star
As$constant$as$it$seems,$Polaris,$the$North$Star$that$
we$see$in$our$night$sky,$has$not$always$been$our$North$
Star.$$This$is$because$Earth$wobbles$on$its$axis$as$it$
rotates,$like$a$spinning$top.$$While$a$top$can$make$one$
complete$wobble$in$a$second,$it$takes$Earth$26,000$
years$to$complete$one$wobble$– or$precession.$$The$
means$that$Earth’s$axis$points$to$different$stars$over$
the$centuries.$$For$example,$around$3000$BC,$the$North$
across$the$seas$
before$the$
invention$of$the$
compass$and$the$
sextant?$$The$
earliest$sailors$
followed$the$
coastline$as$far$as$
they$could,$using$
features$on$land$to$
mark$their$
location.$$But$
when$their$
journey$took$
them$far$from$
land,$they$relied$
on$the$sky.
Early$sailors$knew$that$the$Sun$rises$in$the$east$
and$sets$in$the$west,$and$they$used$that$knowledge$
to$guide$them.$$So$if$they$sailed$into$the$rising$Sun,$
they$knew$they$were$heading$east.$$If$they$turned$
to$the$right,$putting$the$rising$Sun$on$their$left$
side,$they$knew$that$they$were$heading$south.$
At$night,$these$ancient$mariners$steered$by$the$
stars.$$The$North$Star$proved$a$stable$marker$in$
the$Northern$Hemisphere$because$Earth’s$
northern$axis$points$to$the$North$Celestial$Pole$
(celestial$means$“dealing$with$the$sky;$heavenly”).$$
The$North$Star,$Polaris,$is$the$star$currently$closest$
to$the$North$Celestial$Pole.$$As$Earth$rotates$on$its$
axis,$the$stars$in$the$night$sky$seem$to$move$in$a$
circle,$because$they$are$fixed$relative$to$Earth.$$But$
the$North$Star$remains$in$one$spot$in$the$Northern$
Hemisphere$sky$at$all$times,$and$all$the$other$stars$
seem$to$rotate$around$it.$$The$farther$north$a$sailor$
traveled$in$the$Northern$Hemisphere,$the$higher$
the$North$Star$appeared$in$the$sky.$$The$farther$
south$one$sailed$in$the$Northern$Hemisphere,$the$
lower$the$star$appeared$in$the$sky.$$
Many$sailors$of$old$used$a$handy$tool$to$help$
measure$precisely$how$high$or$low$a$star$was$in$
the$sky:$their$fingers!$$By$holding$his$arms$straight$
out$in$front$of$him,$a$mariner$laid$his$fingers$on$
top$of$each$other$to$measure$the$“height”$of$a$star$
such$as$the$North$Star$from$the$horizon.$$Because$
the$height$of$Polaris$above$the$horizon$is$equal$to$
the$latitude$at$a$particular$location,$sailors$could$
use$the$star$to$estimate$their$location.$$They$
would,$for$example,$turn$west$or$east$once$a$
particular$star$selected$for$navigation$was$two$
fingerRwidths$above$the$horizon.$$Very$clever!$$
Although$the$skies$are$still$important$in$
guiding$ships,$today’s$sailors$use$computer$and$
satellite$technology$– such$as$the$Global$
Positioning$System$(GPS)$– to$guide$their$travels.$$
Navigators$have$come$a$long$way$since$the$days$of$
steering$by$the$stars.
Constant$as$the$North$Star
As$constant$as$it$seems,$Polaris,$the$North$Star$that$
we$see$in$our$night$sky,$has$not$always$been$our$North$
Star.$$This$is$because$Earth$wobbles$on$its$axis$as$it$
rotates,$like$a$spinning$top.$$While$a$top$can$make$one$
complete$wobble$in$a$second,$it$takes$Earth$26,000$
years$to$complete$one$wobble$– or$precession.$$The$
means$that$Earth’s$axis$points$to$different$stars$over$
the$centuries.$$For$example,$around$3000$BC,$the$North$
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