2. - The Earth revolves around the sun
from west to east. The speed of the
earth’s orbit is about 108,000 km/hr
(30000 meter per second) during an
orbit it travels 940 million km.
- The earth completes one revolution
every 365.242199 mean solar day,
almost 365 and ¼ days and that is
365 days, 5 hours, 48 minutes and 46
seconds.

3. • Perihelion - the earth is closet to the sun, happens during
January 3 with a distance of 147,098,074 km
•Aphelion – The earth’s distance is farthest from the sun,
happens during July 4 with a distance of 152,097,701 km

4. Earth moves very fast. It spins (rotates) at a speed of about
1,000 miles (1600 kilometers) per hour and orbits around
the Sun at a speed of about 67,000 miles (107,000
kilometers) per hour. We do not feel any of this motion
because these speeds are constant. The spinning and
orbital speeds of Earth stay the same so we do not feel any
acceleration or deceleration. You can only feel motion if
your speed changes. For example, if you are in a car which
is moving at a constant speed on a smooth surface, you will
not feel much motion. However, when the car accelerates or
when the brakes are applied, you do feel motion.
F
Y
I

5. • Sidereal time - From a given observation point, a star
found at one location in the sky will be found at nearly the
same location on another night at the same sidereal time.
This is similar to how the time kept by a sundial can be used
to find the location of the Sun.
• Sidereal day – is about 23 hours, 56 minutes, 4.0916
seconds. The time it takes to make a one rotation.
 Precession - is a change in the orientation of
the rotational axis of a rotating body.
- The period of earth’s
precession is every 26,000
yrs caused by the
gravitational pull of the sun
and moon.
VEGA (Brightest star in
constellation of lyra) will be the
next northern pole star