Download Apparent Motions of Celestial Objects

Apparent Motions of Celestial
Objects
Apparent
Motions of Stars
An apparent
motion
Polaris
Some stars
near Polaris
(North Star)
move in a
complete
circle.
Apparent Motions
of the Planets and
the Moon
The position of planets
in the sky does change
throughout the year due
to their revolutions
around the sun.
The position of the
Moon in the sky
changes each evening –
rising from the east 50
minutes later each
evening and shifting
more eastward
(retrograde motion)
when compared to
background stars.
Apparent Motions
of the Sun – The
Celestial Sphere
The “apparent motion” of the Sun is the
same as that of the stars, planets and
Moon. The Sun “appears” to rise from
the east and set in the west.
West
South
North
East
Apparent Motions
of the Sun – The
Celestial Sphere
In the Northern Hemisphere:
The Sun rises due east and sets due west in
the beginning spring and fall.
In the Northern Hemisphere:
The Sun rises north of east and sets
north of west in the summer.
The sun’s altitude at noon is highest
during the year.
The sun’s “apparent path” across the
sky is at its longest (greater than 12
hours).
In the Northern Hemisphere:
The Sun rises south of east and sets
south of west in the winter.
The sun’s altitude is low in the sky.
The sun’s “apparent path” across the
sky is short (less than 12 hours).
Geocentric
Model
Throughout human history, ancient
civilizations and modern science have
sought to explain the “apparent motions
of celestial objects in the sky.
This model was widely
accepted by European
cultures until the 16th century.
Heliocentric
Model
This model is widely accepted
by most modern cultures.
In this model, the Earth
rotates upon an
imaginary axis and
revolves around the
Sun.