1.36 understand that:  the universe is a large collection of billions of galaxies  a galaxy is a large collection of billions of stars  our solar system is in the Milky Way galaxy

32. - The universe contains many galaxies
    - Each galaxy contains many stars
    - Each star has its own solar system
    - Our solar system is in a galaxy called the Milky Way
    

1.35 use the relationship between orbital speed, orbital radius and time period

0. orbital speed = 2  x π  x orbital radius time period /time period
   
   v = 2 x π x r / t
   

1.34 describe the differences in the orbits of comets, moons and planets

Planets and moons both orbit in circle paths
Comets orbit in ovals known as ellipticals

1.33 explain that gravitational force:  causes moons to orbit planets  causes the planets to orbit the sun  causes artificial satellites to orbit the Earth  causes comets to orbit the sun

if an object entres the field of another objects gravitational force, it will travel around the object in an orbit.

This causes...
- planets to orbit the sun
- artificial satellites to orbit earth
- comets to orbit the sun
- moons to orbit planets

1.32 understand gravitational field strength, g, and recall that it is different on other planets and the moon from that on the Earth

Gravitational field strength (g) is how strongly something pulls an object towards it. 

On Earth it is 9.8 (rounded to 10)

Earth has a higher gravitational field strength than the moon. This is because they have different masses, the Earth has more mass than the moon, therefore the Earth has a bigger gravitational field strength than the moon - the bigger the planet/object (as comets and stars can have g too) the bigger the gravitational field strength.