GED Science Lesson 12

1. Age of Earth
&
Solar System
GED Science

2. Overview
Lesson 1: Age of the Earth & Structure of the Earth
Earth: a spherical shape, flattened at the poles, and bulging at the
equator.

3. Earth Layers
Composed of three main
layers the Crust, the Mental
and the Core

4. Crust
-Made of granite, basalt, gabbro and
other types of rocks.
-3 to 6.8 miles under the ocean and 12
to 40 miles thick below under the continents.
Mantle
-Silica and metal-rich minerals
Core
-Outer core --> liquid iron
-Inner core --> Solid ion

5. Age of Earth
Scientists use three major types of evidence when
determining the age of Earth and the objects on
Earth; landforms, fossils, and radiometric dating.
The process that build up and wear down
landforms today are the same process that have
been at work throughout Earth’s history.
Understanding these process allows scientists to
learn about Earth’s history just by looking at the
structure and composition of landforms.

6. Age of Earth
Over time, as sediment (weathered material) settles it becomes
compacted into layers of sedimentary rock. Since new sediment is added
to the top of sedimentary rock, the youngest layers are at the top and
oldest layers are at the bottom.
This allows scientists to determine the relative age of the layers in a
landform.

7. Fossils
Fossils are remains (shell or bones) or evidence
(imprints) left behind by dead organisms.
Fossils are most often found in sedimentary rock.
The age of the fossil can be determined by
looking at the layer it is found in.

8. Fossils
• Provides the exact, or absolute, age of objects on Earth.
• Some elements have radioactive isotopes, or versions that turn into another
element radioactive decay, by losing a proton.
The amount of time it takes half of
an isotope’s atom to change into
another element is called the half-life.

10. Solar System

11. Solar System
Star; the SUN
Plants
All objects exert gravitational force on each other.
Sun’s gravity keeps all other objects orbiting around it.
The largest objects in the solar system are the round-shaped planets.

12. Three major groups of planets
Terrestrial Planets: the four smaller planets located closest to the sun,
all have rocky surfaces and also called inner planets.
Gas giants: The four larger planets further from the Sun, all have
gaseous surface.
Dwarf Planets: Resemble a small planet but lack certain technical
criteria that are required for it to be classed as a planet.

16. Other objects in solar system
Any object in space that orbits a planet is called a moon.
Asteroids: a large, irregularly shaped chunk of rock mostly found in
asteroid belt.
Comets: frozen gasses and dust particles, usually smaller than
asteroids. Some comets orbits the sun continuously. Others orbit the
sun once and then travel off into space.
Halley’s Comet is a famous comet that continuously orbits the sun. Its
orbit passes by Earth every 76 years.

18. Revolution: Earth orbits or revolves around the sun. One revolution
takes 365 ½ days which is called Earth Year.
Rotation: Earth also spins on its axis. Each completes one rotation in
every 24 hours which is called rotation of Earth day.

19. Eclipses and tides
• Interaction between Earth, the moon, and sun cause Earth to
experience eclipses and tides.
• An eclipse is caused by the position of the sun and moon when one
object blocks light from reaching another object.
• The two types of eclipses that can occur; solar eclipse and lunar
eclipse.

20. Solar eclipse: the moon blocks sunlight from reaching Earth.
Lunar eclipse: Earth blocks sunlight from reaching the moon.

21. Tides
The daily rises and falls of ocean levels are called tides.
High tides occurs when an ocean reaches its highest point on the
shore.
Low tides occurs when the ocean reaches its lowest point on the shore.

22. As the moon orbits Earth, its gravity pulls on the water in the ocean.
This causes the ocean to bulge on the sides closest to and opposite of
the moon.
Shores within the bulge areas experience high tide.
Shores not located in the bulge areas experience low tide.

24. Sun’s gravitational force also attracts tides. When the sun is in line with
the moon, they both pull the ocean in the same direction. This cause
extra high and low tides called the spring tide.
When the sun and moon are perpendicular to each other, they pull the
ocean in different directions causing causing minor differences in high
and low tides called neap tides.