Astro NOtes2

Astro NOtes2 - Astro October 6th Last Time Comprative...

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th Last Time Comprative planetology Our solar system Jovians and Terrestrials Jupiter like and Earth Like Goal: Exlain differences Survey of abundance of elements The universe as a whole : 75% Hydrogen, 24% helium, 1% other by mass The solar system: 71%hydrogen, 27% helium,, 2% other Hydrogen/ helium- 98% of the solar system Sun/ Jovians – not so much in terrestrials Jovians much bigger than terrestrials because theres more building material. Jovians are far from the Sun, terrestrials are closer. Refine Question : How did matter get distributed in the way it did? (see statement above) Core Message: Planets are products of environment in which they grow. First Major Theme : Planetary atmospheres Issues: what holds an atmosphere in place? What causes an atmosphere to grow, or diminish? Balance of Three Factors 1. Gravity at planet’s surface escape speed from planet 2. Temperature on planet’s surface 3. Molecular weight of gas (How heavy is an individual molecule 2 and 3 tell you the speed of gas molecules Escape speed from a planets surface. Mass M Radius R Speed V The item has a M and an R and you through it out with a speed V The question is does it fall back to you? Definition of ES: the minimum speed a projectile (Rock, Gas molecule) needs to escape to infinity from a planets surface. Earth: 11.2 km/s. JupiterL 59.5 Km/s, Moon 2.4 km/s sun 618 km/s. The basic rule is the more gravity the harder it is to escape. Property of gravity.
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This note was uploaded on 12/01/2009 for the course ASTR 50800 at USC.

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Astro NOtes2 - Astro October 6th Last Time Comprative...

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