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Lecture 5

Astronomy 2232F/G Lecture 5: 2232 Lecture 5-Planetary AtmospherePremium

2 pages82 viewsSpring 2018

Department
Astronomy
Course Code
Astronomy 2232F/G
Professor
Els Peeters
Lecture
5

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Lecture 6
Slide 1
- . billion years ago all planets had identical atmosphere’s
o 95% H, 5% He =primary
o Planet doesn’t have this today
- Today’s atmosphere=secondary
Slide 2
- Planets have very little of primary atmosphere left today
- A large impact will blow out part of the atmosphere but thought to mainly be lost
slowly
Slide 3
- Two main ways you can get rid of an atmosphere:
1. Gravitational field strength
2. Temperature of gas
Slide 4
- It takes more energy to get something off the surface of the earth than the moon
- As gravity increases it’s harder to launch something into space
Slide 6
- Plot provides prediction of gases that should be in the atmosphere of a planet
o Theoretically correct
- Gas giants from other solar systems can keep all their gases because it’s harder for
things to escape
- Moon cannot retain any gases
- Mercury and Mars?
Slide 7
- Processes in the atmosphere of Mars (chemical reactions) will destroy methane if
methane is found it means it was produced recently because it’s composition is
eventually change
- This makes the plot incorrect
- Methane is produced through outgases deep in surface of a planet OR through
organisms
- We know mars is not volcanically active and therefore methane could conclude
biological activity on mars
Slide 8
- Ways to provide gas to an atmosphere
o Geological activity amount of outgassing, more activity =more outgassing =
thicker atmosphere (i.e. Volcanism)
o Burning of fossil fuels (if there is civilization that will do that)
o Impact cratering
o Size and mass of planet surface gravity escape velocity
o Distance from sun
o Living organisms change composition through waste products
o Chemical reactions different molecules are created and destroyed in
various environments, higher temperatures mean faster reactions
Slide 10
- Don’t need to know equation for calculating effect of temperature
- Why is temperature higher than it should be on earth and Venus?
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