1. Life on Earth

2. Think WAAAAAY Back… With your group, write the 7 properties of life
Take turns...
Person 1: write down 1 property of life, then pass the paper to Person 2
Person 2: write down another property of life, then pass the paper to Person 3

3. What is life? All living things have these 7 properties:
Made of a cell(s)
Have DNA
Able to reproduce
Grow & develop
Obtain & use energy
Respond to stimuli
Maintain homeostasis
If matter does not have all 7 properties, then it is not living!!

4. Why Can Life Exist on Earth??
Distance from the Sun
Earth’s atmosphere
Presence of Water
Gravitational Pull

5. Our planet is the perfect average distance from the sun!
REASON #1
Our planet is the perfect average distance from the sun!

6. Our Earth
Earth is the 3rd closest planet to the sun (93 million miles away)
Earth’s mass has been most recently calculated at 5.98 × 1024 kg (*you obviously can’t measure this!)
It has continents!
Inner core temp: 13,040 degrees F

7. Earth & Sun Perfect average distance from the Earth
So humans don’t burn or freeze to death!
Sun fuels all life processes
All organisms get their energy from the sun….somehow!
Most common way is by photosynthesis

8. Remember Photosynthesis…?
CO2+H2O+ENERGY (sunlight)  O2 + C6H12O6
Sun’s energy is transformed into chemical energy
If there is no sun, there is no ENERGY for photosynthesis to occur therefore…we could not survive!

9. Also, without the Sun, rain would be next to impossible, because the water cycle could not occur!

10. Earth has a very unique atmosphere!
REASON # 2
Earth has a very unique atmosphere!

11. 4 Spheres of Earth Lithosphere- earth’s crust (soil, rocks, minerals)
Hydrosphere- earth’s water
Atmosphere- the gases in the air
Biosphere- all living things

12. Earth’s Atmosphere Sustains Life
Earth’s atmosphere is a combination of gases:
Nitrogen, Oxygen, and Argon remain constant; while there are varying trace amounts of CO2 and water vapor

13. What’s In Air: 78.08% Nitrogen (N2) Oxygen (O2) 20.95% Argon (Ar)
0.93%
Neon, Helium, Krypton, other
0.0001%

14. What makes these gases important?
Oxygen is critical, but so are the other gases in the atmosphere!
Gases absorb heat from the sun, which warms the atmosphere, creating the “greenhouse effect”
(Without these gases, the
surface of earth would be
about -16˚F!)

15. Our atmosphere= Our protection!
The atmosphere protects us from meteors!
Small meteorites burn up in the atmosphere before reaching Earth. Those that do hit the surface and create an impact crater are quickly eroded due to weather and the evidence is lost.
The moon has no atmosphere… every meteorite coming towards it will hit it!
Moon Earth

16. REASON # 3
Water exists here!

17. Speaking of Water….
Our planet is dominated by water- more than 70% of the Earth’s surface is covered with this simple molecule
The hydrosphere is estimated to contain about 1.36 billion km3 of water
If all our planet’s ice melted, sea-level
would rise by about 70 meters!

18. CO2+H2O+ENERGY (sunlight)  O2 + C6H12O6
Water is required for photosynthesis to occur!

19. REASON # 4
GRAVITY!!!

20. Earth’s Gravity What is gravity?
the tendency of objects with mass to accelerate towards each other
The Sun’s gravity holds our solar system together
Objects with more mass= more gravity
Earth’s mass creates an
ideal gravitational pull