Our Sun
Most important object in our solar system
- 99.9 % of the total mass
- Jupiter’s mass is 0.1% of the Sun’s
- M1P2 = a3 (Newton’s version of Kepler’s III’rd law)
- 99.999...% of the luminous power
- Learn about Sun (Chap. 8)
- Learn how the Sun and Solar System came to be (Chap. 20)
Nature of Sun
- Hot ball of gas
- mostly H and He, traces of heavier elements
- Held together by gravity
- universal, attractive, force (Newton)
- Kept from collapsing by hot (thermal) gas pressure
- This is the pressure that makes a baloon expand
- and keeps automobile tires from collapsing