Chapter 8 paragraph 1: a manned spacecraft

• Aardrijkskunde
• Middelbare school
• havo
• Leerjaar 3

At the end of this class

you can explain what is needed for a sustainable life on earth

What makes life on earth possible?

Five factors

1. Distance from the sun
2. Atmosphere
3. Gravity (force of attraction from the earth)
4. Water
5. Food (natural resource)

1 of the 5 is missing? No life possible. 

1. Distance from the sun

• Without natural greenhouse effect on earth: - 18 degrees celcius
• The atmosphere keeps the warmth on earth: on average 15 degrees celcius

2. Atmosphere

• The atmosphere contains oxygen, which we need in orde to breathe
• We breathe carbon dioxide out (CO2) 
• This helps plants and trees to grow, and they make oxygen out of carbon dioxide. 

3. Gravity

• The force of attraction of the earth ensures that gases  remain in the atmosphere and do not disappear into space. 
• It also means that objects do not float, but remain on the ground.  Without gravity, people would be hurled into space.  

4. Water

• Essential for life on earth: the female body consists for 50% of water, the male body for 65%.  
• Plants can also not exist without water
• Most of the water is in the oceans (97,5%). Most of the fresh water is stored in ice or deep in the ground (in aquifers).  Het meeste water zit in de oceanen (97,5%). Only a small part of the fresh water is available to us in rivers or lakes.

5. Food

• People need food to survive
• It is an essential natural resource on earth for humans

Sustainability?

To work

• Read paragraph 1
• Make assignments (see workplanner)