ASTR 1000 Lecture Notes - Lecture 17: Accretion Disk, Solar Wind
18 Jun 2018
School
Department
Course
Professor
Class 17
Atmospheres of the Terrestrial Planets
-Escape Velocity = is the minimum speed needed for an object to escape from the
gravitational influence of a massive body. Two properties needed to calculate EV: mass and
radius
-Example: Earth 11km/s, Moon 2.4km/s (no atm), Mercury 4.4km/s (no atm)
-Behaviour of Gases = gas has certain temperatures.
-Temperature of gas changes due to “distance” from the sun.
-When you are measuring temperature of a gas, you are measuring the AVERAGE
SPEED.
-heavy mass = slow movement
-light mass = fast movement
-Primary Atmosphere = is an atmosphere of a planet that forms by accretion of gaseous
matter from the accretion disc of the planet's sun. Primarily hydrogen and helium. Planets
such as Jupiter and Saturn have primary atmospheres. Primary atmospheres are very thick
compared to secondary atmospheres like the one found on Earth.
-Secondary Atmosphere = A secondary atmosphere is an atmosphere of a planet that did not
form by accretion during the formation of the planet's star. A secondary atmosphere instead
forms from internal volcanic activity, or by accumulation of material from comet impacts. PA
leaks away and gets replaced with the secondary atmosphere.
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- How come Earth is the
odd one out?
Made up of two gasses
(80% nitrogen, 20% O2)
It’s not missing CO2, it’s
just not in the ATM. à
dissolved in ocean, fossil
fuels (coal, natural gas and
oil), calciferous rock (lime
stones, shells)
-Mars has been slowly
loosing its ATM over time
- If you took all the CO2 out into
the atm then we would end up
like the other planets.
Mercury
-Discovery of smooth areas near
north pole.
Runaway Greenhouse Effect - is a
process in which a net positive feedback between surface temperature and atmospheric opacity
increases the strength of the greenhouse effect on a planet until its oceans boil away.
- positive feedback loop = is a process that occurs in a feedback loop in which the effects
of a small disturbance on a system include an increase in the magnitude of the
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Escape velocity = is the minimum speed needed for an object to escape from the gravitational influence of a massive body. Two properties needed to calculate ev: mass and radius. Example: earth 11km/s, moon 2. 4km/s (no atm), mercury 4. 4km/s (no atm) Behaviour of gases = gas has certain temperatures. Temperature of gas changes due to distance from the sun. When you are measuring temperature of a gas, you are measuring the average. Speed. heavy mass = slow movement light mass = fast movement. Primary atmosphere = is an atmosphere of a planet that forms by accretion of gaseous matter from the accretion disc of the planet"s sun. Planets such as jupiter and saturn have primary atmospheres. Primary atmospheres are very thick compared to secondary atmospheres like the one found on earth. Secondary atmosphere = a secondary atmosphere is an atmosphere of a planet that did not form by accretion during the formation of the planet"s star.
