1. “Don’t make me read, make me understand “
Full of ingredients to make your child a genius.
“Don’t make me read, make me understand “

2. Class 3 : Solar system formation, and the variety of surface-types.
Finish discussion from last class…
Recap about the patterns that we find in the solar system
Theory for Solar System formation
How do we test this theory?
Varieties of surfaces in the solar system
Classifying surfaces
The processes at work

3. Recap: Characteristics of the solar system
All planets (apart from Pluto) orbit in the same plane… solar system is flat

4. All planets orbit the Sun in same sense.
The Sun and all planets (apart from Venus and Uranus) rotate in the same sense as the planets orbit the Sun.
Inner planets are small and rocky, but outer planets are large and gassy.
There are also asteroids and comets
All asteroid and short-period comets are usually in planetary plane and orbit in same sense
Long period comets are random in direction and sense.

5. I: Solar system formation
How did all of this come to be?
A good theory needs to
Explain the facts we just listed.
Be as simple as possible (but consistent with the laws of nature).
Be testable.
Our best theory is the Collapsing Gas Cloud theory.

6. Phase I (started 5 billion years ago)
Gas Cloud starts to collapse in on itself due to its own gravitational pull.
As it collapses, it rotates faster and flattens
Phase II (lasted 100 million years)
The central part of the gas cloud forms the Sun – nuclear reactions start in its core.
Phase III
Dust grains and ice crystals start to condense out of flattened gas disk
Grains grow via collisions to form planetesimals (objects the size of the Moon)

7. Stage V – 4.5 billion yrs ago to present
Stage IV
Planets grow by successive bombardment of planetesimals
Eventually, there are no more planetesimals left
Outer massive planets grab the remains of the gas from the cloud
Stage V – 4.5 billion yrs ago to present
Planets formed
Still some debris around (asteroids and comets) that occasionally hit the planets.

9. Questions…
How would we ever test our theory for the formation of the solar system?
The effects of impacts on planetary surfaces in the Solar System

10. The Moon (near side)
The Moon (far side)
Europa (a moon of Jupiter)

11. Callisto (a moon of Jupiter)
Gaspra (an asteroid)
Io (a moon of Jupiter)
Triton
(a moon of Neptune)
Titan (a moon of Saturn)

12. Thanks
Submitted by
Abhishek
Mumbai

13. If you also want to share your own or your kid’s presentation(ppt) please send it on

14. “Don’t make me read, make me understand “
Full of ingredients to make your child a genius.
“Don’t make me read, make me understand “