EARTH'S ATMOSPHERE

Why do astronauts wear spacesuits?

WHY DO ASTRONAUTS WEAR SPACESUITS

• Space is a vacuum
• There is no atmosphere in space
• Spacesuits provide oxygen and air pressure for astronauts

WHAT IS ATMOSPHERE?

• It is the envelope of gases that surrounds the planet
• It consists of nitrogen, oxygen, carbon dioxide, water vapor and other gases.
• It also contains particles of liquid and solids.

NITROGEN

• Most plentiful gas in our atmosphere.
• Makes up three fourths of the air we breathe.
• Nitrogen is an element
• Nitrogen is found in all living things

OXYGEN

• Oxygen makes up only about 21% of the air we breathe
• Oxygen is necessary for plants and animals to get energy from their food
• Fires need oxygen to burn
• Rust is formed when steel reacts with oxygen to form iron oxide

CARBON DIOXIDE

• Carbon dioxide is a molecule made up of carbon and oxygen.
• It is only 1% of the atmosphere, but is essential to life.
• Plants must have CO2 to perform photosynthesis.
• Animals produce CO2 when they burn food for energy.
• CO2 is also produced when fuel is burned by engines.

OTHER GASES

• Nitrogen and Oxygen make up 99% of dry air.
• Argon makes up most of the other 1%.
• The remaining gases found are called "trace" gases because they are found in very small amounts.

GOLDILOCKS EFFECT

• Our planet is the "just right" distance from the sun for us to survive
• The ratios of gases in our atmosphere is "just right" for all living things to survive.

If an alien came here from Mars, would he be able to breathe our air?