Planet Earth Earths Dimensions Regents Earth Science The

Planet Earth – Earth’s Dimensions Regents Earth Science

The Shape of Earth – Earth is a sphere How do we know? ? ? Evidence of Earth’s Spherical Shape 1. ) Ships “disappear” as they sail from land / the mast of a ship is the first to appear over the horizon 2. ) Change in nighttime sky – this would not occur is Earth was flat 3. ) During an eclipse, Earth’s shadow is a sphere

Evidence of Earth’s Spherical Shape Continued 4. ) Observation of Polaris changes as one travels north or south 5. ) Photographs taken by orbiting spacecrafts

The TRUE Shape of Earth Model that best represents Earth – Sphere/ Globe BUT…. The sphere is not perfect The actual shape of Earth = Oblate Spheroid This means that Earth is slightly flattened at the poles and bulges slightly at the equator

How do we know Earth is NOT a perfect sphere? ? ? Weight = gravitational pull towards Earth’s center An object weights more at the poles and less at the equator ……. So the object must be CLOSER to Earth’s center at the poles and FARTHER from Earth’s center at the Equator

Earth’s Diameter and Circumference Diameter (km) Circumference (km) Polar 12, 714 40, 008 Equatorial 12, 756 40, 076

Earth’s Structure Earth’s outer portion is generally classified into three major parts: 1. ) Lithosphere – The rigid shell of rock that surrounds the more fluid inner layers and solid core Oxygen and Silicon are the two most common elements Find the data table on the ESRT showing the elements in the lithosphere

2. Hydrosphere- Consists of Earth’s liquid water – oceans, lakes, rivers, and water in the ground Oceans average depth about 3 -5 km 70% of Earth is ocean

3. Atmosphere: The shell of gases that surrounds Earth Most common gases in atmosphere - Nitrogen 78% - Oxygen 21% - Other – 1%

Layers of the Atmosphere 4 Main Layers – LOOK IN ESRT PAGE 14 Troposphere: Layer closest to Earth, where weather takes place Stratosphere: Ozone layer at top and where planes fly Mesosphere: Very cold, where most meteors burn up Thermosphere: VERY warm, extends into space Each layer is characterized by differences in temperature!!