How astrolabe works?

Answer 1

The astrolabe was used by the ancients ( III siecle B.C. in Greece)

for observing the relative positions and altitudes of celestial bodies.

In the Middle Age it become a navigational instrument by the addition

of tables of the Sun´s declination ( angular distance north or south of

the celestial equator), which permitted the sea Navigants to find their

latitude.

In its earlier form it consisted of a disk of wood suspended by a ring.

Around the disk edge were marked the degrees of the circle; a pointer

along which the sun or another star could be sighted was pivoted on a

center pin.

Later on the astrolabes were often made of metal with a plate with the

map of the stars and the zodiac circle on the reverse side. It was then

possible determine the time of the day: after measuring the sun´s altitude,

its position was noted on the circle of tfuyjfyjytjfhe zodiac, a line drawn to a circle

of hours showed the time.