KEPLER AND HIS LAWS

1
KEPLERANDHISLAWS
St Josephs College, London. Year 10
2

• Johannes KEPLER and Galileo GALILEI were
  astronomers working at the same time around 1610.
  They discovered how planets and moons move around
  each other and came up with laws that are still
  true today.

3

• They were very different people!

KEPLER
Born 1571 and had a dreadful childhood.
Mother a witch.
Father often absent and uncaring.
Devout Protestant
4
Born 1564 in Pisa, Italy. Pleasant childhood
GALILEO
Supportive family who gave him lots of
encouragement.
Studied at University to be a doctor but changed
to Maths.
Devout Catholic
5

• Kepler was often ill and had bad eyes.

He was thought to be a bit strange because he was
very clever and very religious. He didnt have
many friends.
Went to University and was studying to be a
minister when he was sent to be a teacher of
Maths and Astronomy.
Not a good teacher, a bit of a loner
6

• Galileo liked publicity and made friends and
  enemies easily.

Together they made sure that the views of
COPERNICUS became accepted as true. We now
believe that the Earth orbits the Sun.
7

• KEPLERS LAWS

After studying data about Mars, Kepler was able
to say
1. The orbits of planets are ellipses, with the
Sun at one focus of the ellipse.
2. The line joining the planet to the Sun sweeps
out equal areas in equal times as the planet
travels around the ellipse.
8

• 3. The ratio of the squares of the periods of two
  planets is equal to the ratio of the cubes of
  their semi-major axes.

a cubed
We used M
p squared
With our pooled and averaged results..
9
GANYMEDE
amplitude 7.375 Jupiter diameters
period 6.75 days
After converting amplitude to km, and then
Astronomical units, and then changing period to
years we obtained the result of
10
0.001025823 Solar masses

• We converted this to kg and our final calculation
  gave the mass of Jupiter as 2.04046 x 1027 kg.

11
Io
a 3.7 Jupiter diameters
p 2 days
Mass of Jupiter 2.93492 x 1027kg