Writing Term Papers on Uses of
Astronomy Prior to 18th Century
Astronomy is the oldest of all natural sciences. Since 3000 BC man has been
fascinated by celestial phenomena like the rising and the setting of the sun,
the phases of the moon and the movements of the sun and the planets. The time
arrangements are derived from the celestial phenomena. The Babylonians and
Chaldeans seem to have been the first peoples to study the skies and the stars.
From their quest of knowledge, astrology came into being. Greeks were the second
civilization who advanced the science of astronomy.
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Uses of Astronomy before 18th Century
Men, since the very beginning, have been fascinated by the science of astronomy.
As man advances in the field of astronomy, men had found many uses of this
interesting branch of science. Let us see some of the uses of astronomy before
18th century.
Navigation
When the early navigators started venturing away from the sight of land they
started developing methods of navigating involving the heavenly bodies. The
people that inhabited the south Pacific Islands were able to travel between
islands using methods unknown to Europeans. Some of the tools that European
Navigators used are:
The Astrolabe
The Astrolabe, which means “star-taker”, was one of the oldest instruments used
by the astronomers but it did not serve at sea until 1480. It was at this time
the Portuguese drew up the rules for taking an altitude of the sun to establish
latitude.
The Greeks probably invented astrolabe. It was used for surveying as well as
astronomy. The scale read down from zenith, 0 so the zenith distance was read
directly. In Northern latitudes an uncorrected sight of Polaris could be read
directly. There were many other scales related to astronomical work on these
expensive instruments. Arabs crossing the deserts probably used one type of them
long before they were used at sea.
The Cross Staff
The Portuguese in the 13th century found they needed a better method of
obtaining an altitude. Astronomers aided Prince Henry the Navigator in
developing the cross-staff. The instrument was cheap enough and simple enough
for use at sea.
In the 16th Century additional transversals were added along with extra scale on
the cross-staff. This gave the navigator the ability to get a larger range of
angles.
Calendars
The ancient Egyptian began numbering their years when the star “Sirius” rose at
the same place as the sun. The Egyptian Calendar was the first solar calendar
and contained 365 days. These were divided into 12, 30 days months and five days
of festival. From astronomical calculations, Sirius and the Sun coincided in
4241 and 2773 BC, so either of these could have served as Egyptian year 1.
The calendar used by the ancient Greeks was based on the Moon, and is known as
the Metonic calendar. This calendar was based on the observations of Meton of
Athens, which showed that 235 lunar months made up almost exactly 19 solar
years. This 19-year cycle is known as the Metonic cycle. However, given a
nominal twelve-month year, additional lunar months needed to be added to
synchronize the cycle. These were added in years 3,5, 8, 11, 13, 16 and 19 of
the cycle. Around 325 BC Callippus modified the calendar by noting that 4 19
years Metonic cycles with 940 months were very close to 27,759 days. This is
called the Callipic cycle. A lunar-based calendar is still used by some
religious sects to determine holidays. Easter, for instance, generally occurs on
the first Sunday following the first full moon after the vernal equinox,
although the actual scheme is a bit more complicated.
The Roman calendar originally started the year with the vernal equinox and
consisted of 10 months, having a total of 304 days. The 304 days were followed
by an unnamed, unnumbered period in winter. The Roman Emperor Numa Pompilius
(715-673 BC) introduced February and January between January and March,
increasing the length of the year to 354 or 355 days. Then in 450 BC February
was moved to its current position. The calendar currently used worldwide based
on a cycle of 400 years comprising 146,097 days, giving a year of average length
365.2425 days. Hence, after all the above discussion, it can easily be said that
astronomy has been used for the betterment of men since it’s very beginning.
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