Earth's Rotation and Revolution
PHYSICAL GEOGRAPHY 101

Earth's Place in the Solar System

Basic Structure of the Solar System
Sun
Terrestrial Planets (Inner planets)
• Mercury
• Venus
• Earth - Moon
• Mars
• Asteroid Belt
Gas Giants (Outer planets)
• Jupiter
• Saturn
• Uranus
• Neptune
Dwarf Planets (Pluto)
Oort Cloud.

Revolution of the Earth

The Earth revolves around the Sun
Time it takes the Earth to complete one orbit around the Sun = 1 year
1 year = 365.25636 days
The orbit is an elliptical path
The orbit defines a plane - Ecliptic Plane
Average orbital velocity = 29.8 km/s
Orbital length = 940,416,480 km
Closest approach to the Sun = 147 million km
Farthest distance from the Sun = 152 million km

Rotation and Tilt of the Earth

The Earth rotates on its axis
One complete rotation = one day
1 day = 24 hours
Equatorial mean rotational velocity = 0.4651 km/s
Axis is tilted relative to the ecliptic at 23.5 degrees (23°17') from perpendicular to the ecliptic
The axial tilt varies between 22°-24°

Precession of the Axis

At present the Earth's axis appears to point towards Polaris (North Star)
Over time the axis moves - precesses
The axis revolves
The axis completes one complete precession in 25,800 years

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