1. Why does Life Exist on Earth?
Life On Earth
Why does Life Exist on Earth?

2. Essential Standard
6.E.1 Understand the earth/moon/sun system, and the properties, structures and predictable motions of celestial bodies in the Universe.

3. Clarifying Objective
6.E.1.2 Explain why Earth sustains life while other planets do not based on their properties (including types of surface, atmosphere and gravitational force) and location to the Sun.

4. Essential Questions What are the conditions needed for life on Earth?
What conditions on other planets make it unsuitable for life?

5. Earth The Earth is the 3rd planet from the sun
It contains both landmasses & oceans
It is the ONLY PLANET that is known that CAN SUPPORT LIFE
This is why

6. Location from the Sun
Earth is the only planet that is the CORRECT LOCATION from the SUN to have life
Earth’s location from the sun is the reason that conditions for life are possible
If the planet were closer to the sun life would be impossible as it would be if it were further from the sun

7. 6 Conditions for Life
For any planet or moon or anything to support life (anything from bacteria to humans) you have to have 5 conditions
Water
Atmosphere (Oxygen)
Correct Temperature
Light
Correct Gravity
Types of Surfaces

8. Water The first ingredient you need to sustain life is WATER
Water must exist in liquid form or have the ability to become liquid
Water is the breeding ground for chemical reactions essential to life
On earth you can find water in all three medium forms (solids, liquids, gasses)

9. Atmosphere The second key ingredient is the RIGHT kind of Atmosphere
An ATMOSPHERE that can sustain life MUST contain high amounts of OXYGEN
Oxygen is the key in the atmosphere for life to exist

10. Correct Temperature
The third ingredient is having the CORRECT TEMPERATURE for life to exist
The earth is one of two planets (Mars) to have the correct temperature for life to exist
The temperature has to be between degrees
Other planets are either too close (hot) or too far (cold) to sustain life

11. Light The fourth ingredient is LIGHT
To sustain life a planet must have light
Light gives all living things energy and it starts the food cycle
Light is the key to starting photosynthesis which is how plants make their food

12. Food Chain

13. Correct Gravity
The 5th ingredient is the CORRECT amount of GRAVITY on the planet
Remember gravity is the force that holds you to the ground and controls weight
All planets have a gravitational pull to the sun

14. Correct Gravity
The closer the planet to the sun the more gravity they have
The further from the sun the less gravity they have
If the planet is too far from the sun the atom particles you are made up would disintegrate
If you were too close your legs would break because your bones would not be strong enough to handle the increased weight

15. Types of Surfaces
The last ingredient is the CORRECT TYPE of SURFACE for life
The surface of the Earth is composed of both land & water
It is the only planet surface publically known to be conducive to life

16. Why can Earth Sustain Life?
Earth can sustain life and no other planet can because all of these FACTORS exist at the SAME TIME
Correct Distance from the sun
Water in liquid form
Atmosphere with Oxygen
Correct Temperature
Light
Correct Gravity
Right Surface

17. Essential Questions Get with a partner and answer…
What are the conditions needed for life on Earth?
What conditions on other planets make it unsuitable for life?

18. EOG Questions
Which factor makes Earth different from all the other planets in the solar system in its ability to support life?
A) The Earth is exposed to rays from the sun.
B) The Earth has only one moon that orbits around it.
C) The Earth rotates in an elliptical orbit around the sun.
D) The Earth has a breathable atmosphere.

19. Important Points
Earth is the only publically known planet to support LIFE
There are 6 key ingredients to support life
Water in liquid form
Correct Temp
Correct Gravity
Atmosphere w/Oxygen
Light
Correct Surface Type
At least one of these FACTORS does NOT exist on all the rest of the planets in the Solar System