2. DIURNAL MOTION
•apparent daily motion of the heavens
from east to west in which celestial
objects seem to rise and set, a
phenomenon that results from the
Earth's rotation from west to east. The
axis of this apparent motion coincides
with the Earth's axis of rotation.
3. DIURNAL MOTION
• Each day, the Earth rotates once
(west-to-east)on its axis. This
causes us to face different
directions and see different stars.
The stars daily(diurnal)motion
reflects the Earth's spin.
4. ANNUAL MOTION
• Annual motion of the sky — the appearance that
objects in the sky moves relative to the background
stars as observed at the same time of the day and at
the same location on Earth.
• Over the course of a year, the Sun appears to move a
little towards the East each day as seen with respect to
the background stars. This daily eastward drift is <1°
per day (there are 365 days in a year, but only 360° in a
circle).
• As the Earth orbits the sun, the sun appears to move
eastward with respect to the star.
5. ANNUAL MOTION
• Due to the Earth's revolution
• Reflection of the Earth's Orbital Motion
6. PRECESSION OF THE EQUINOXES
• The Earth axis chages direction in a CLOCKWISE
direction with a cycle of about 26,000 years
• Earth axis also precesses (wobble)like a top. The
angle between ecliptic and the equator remains at
23. 5°. but the direction changes. The period of
this precession of the equinoxes is about 26, 000
years
