2-The earth as a heavenly body
Question 1 (GG101)
► is….. the thin shell of air around the world. It gives us the possibility to live on planet
The atmosphere is important for people because …
● Oxygen (O2) and carbon dioxide (CO2) are present in the atmosphere. People,
animals and plants need O2. Plants convert CO2 into O2.
● The atmosphere protects the earth from meteorites (which burn up in the
atmosphere) and from dangerous radiation (which is filtered by the ozon layer).
● The atmosphere regulates the earth’s temperature due to certain gasses. These
gasses make sure that the worst heat during the day is kept out and the warmth is
retained during the night. This is called the (natural) greenhouse effect. If it wasn’t for
the greenhouse effect, the average temperature on earth would be -17⁰C instead of
Greenhouse effect = the ability of the atmosphere to retain warmth.
A shooting star is a common name for the visible path of a meteorite as it starts to burn
when it enters the atmosphere.
Question 3 (GG 55)
A star/ sun is a ball of burning gas in the middle of a solar system. A sun sends out light
Planets orbit a sun. They don’t send out light, but the get light and heat from the sun.
Moons orbit planets. It is possible that 1 or more moons orbit one planet.
Question 5 (GG 54)
a- The earth orbits the sun once a year
(365.2564 mean solar days).
The earth rotates on its own axis every 24 hours.
b- Because of the orbit seasons exist.
Due to the rotation day and night and
time differences exist.
c- Because of the tilted axis of the earth one part of the year
the northern hemisphere faces towards the Sun,
whilst the southern hemisphere is facing away from the Sun.
If the sun lights one part of the earth (day), then the other
half is in the dark (night)
Figure 9: Angle of the sun: summer/ winter
The sun is perpendicular
(vertical) to the Tropic of
Polar day on the north
The sun is perpendicular to
the Tropic of Capricorn
Polar day on the south pole