EARTH

EARTH

1. 3 Features of Earth

   • Atmosphere of mainly nitrogen 78%, oxygen 21%
     • Absorbs UV radiation - causes skin cancer
     • Absorbs energetic X-Rays + Gamma Rays
     • Protects Earth from Meteroids
   • Liquid Water 70%
   • Life in all diverse forms

2. 13,000km

3. Spherical Evidence

   • Ships disappear over horizon
   • Air-crafts fly in arcs than straight lines
   • Satellites orbit Earth - impossible with flat Earth

4. Orbits Sun at ecliptic

5. Skyglow

   • Wasteful light shines sky above urban areas
     • Causes orange background haze
       • Prevents stars and milky way being observed
         • Rural areas ideal for observing
   • Terrestrial Light Pollution
     • Sports Floodlights
     • Domestic Security Lights
     • Motorway Lights

6. Eratosthenes

   • Shadow stick at noon, Alexandria 7 degrees from Zenith
     • Syene 790km further South of Alexandria
       • Circumference 50 times this value: 39,500km

7. Telescopes collect light and produces a focused image

   • Refractor - Convex lens, collects light, brings to focus
   • Reflector - Curved mirror collects light
   • Large Telescopes
     • Higher resolution in proportion to diameter
     • Collect more light in proportion to area
     • Space Telescopes
       • No light pollution
       • No adverse weather problems
       • No atmosphere to blur images
       • Reduced lifetime
       • More expensive
       • Difficult to repair

8. Van Allen Belts

   • 2 Doughnut shaped rings
     • High energetic particles held by Earth's magnetic field
   • Inner Belt
     • High energy protons formed by collisions between cosmic rays + atoms in atmoshere
   • Outer Belt
     • Electrons + other charged particles emitted by Sun
     • Horns dip towards Earth's magnetic poles