Constellations Thesis Book by Nesrin Zidan

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You simply need to know a location’s
latitude—the number of degrees
north or south of the equator—and longitude—the
number of degrees east or west
of the prime meridian—to locate it on the
globe of Earth. A hypothetical line connecting
the North and South Poles passes
via the Royal Observatory at Greenwich,
England, and is known as the prime meridian.
Similar to how the equator designates
the 0° latitude line, it designates the
zero (0°) longitude line.
The latitude and longitude are distinctive
to each city. When the latitude is
preceded by a negative sign, that sign indicates
south, and a positive sign, north. Every
site, including cities, airports, and even
our own homes or apartment complexes,
can be located using only two integers and
sits somewhere on the global coordinate
grid. On the surface of the Earth, one degree
of latitude is equivalent to around 111
kilometers (King, 2019).
Every celestial object, like buildings,
has two coordinates that fix its location:
right ascension and declination, also
known as the object’s celestial coordinates.
Right ascension relates to longitude and
declination to latitude. Since there are no
highways in space, detecting an item with
your telescope requires knowing its coordinates.
Imagine the grid of latitudes and
longitudes on the earth as the surface of a
pliable, translucent soccer ball. You would
be able to gaze up and see lines of latitude
and longitude etched on the sky if you
could push the ball up into a huge sphere
that was centered on the Earth.
The celestial equator, which corresponds
to the 0° latitude line, now circles
the sky, while the north and south celestial
poles stand guard over the poles of the
earth. The celestial equator may be seen
from the equator of the Earth as starting at
the eastern horizon, passing directly overhead,
and descending to the western horizon.
It would also go around the back of
the Earth because we are in a sphere (King,
2019). Celestial coordinates, as opposed to
Earth coordinates, fluctuate because of the
precession of the Earth’s axis.
The equinox points move westward
due to precession at a rate of 50.3
arcseconds each year. The coordinate grid
is shifted along by the equinox as it drags.
Because of this, software and star catalogs
need to be updated often to reflect the latest
“epoch.” Every 50 years, this is carried
out (King, 2019).