Earth and space
Astronomy- (Astro = stars; Nomy= arrangement)
It is the study of the Sun, the Moon, Planets and stars. The
scientist who study astronomy are known as astronomers. The
solar system is explained by two important models:
Geocentric model- Ptolemy stated in 145 AD that Earth is a
sphere and that five planets Mercury, Venus, Mars Jupiter and
Saturn move around it. This model was proposed before the
Heliocentric Model.
Heliocentric model- Nicolaus Copernicus proposed the Suncentric model, which stated that the Earth and planets move
around the Sun in fixed, circular path called orbits.
Galileo was the first person to use telescope to observe the
night sky. His observations supported the theory of Copernicus.
He also observed Jupiter’s four moons.
Issac Newton introduced the idea of gravity. He explained that
the sun, planets and their moons all attract each other with
their gravity, and their speed stops them from falling towards
each other.
Answer the following questions:
1. Which model of the solar system is supported by modern
astronomers? ___________________
2. What attracts the Sun, the planets and their moons to each
other?
3. What stops them from falling onto each other?
Phases of moon
When it is visible moon is the brightest and biggest object in the
sky. The moon is non-luminous (doesn’t have its own light). It
acts like a mirror and reflects sunlight.
The shape of the moon appears to change in a repeating cycle
when viewed from the Earth because the amount of illuminated
moon we see varies, depending on the moon's position in
relation to the Earth and the sun.
The various phases of the moon are:
1. New moon
2. Waxing Crescent
3. Quarter moon
4. Waxing gibbous
5. Full moon
6. Waning gibbous
7. Three quarter moon
7. Three quarter moon
8. Waning crescent
Moon takes 29.3 day to
circle around the Earth.
8. Waning crescent
Moon takes 29.3 day to circle around the Earth.