Astronomy Home
Physics Home
| PLANETARY ATMOSPHERES
(100 points) |
2.1. (1 pt) Mercury's atmosphere is :
a) mostly made of hydrogen
b) mostly made of carbon dioxide
c) mostly made of nitrogen
d) mostly non-existant
2.2 (1 pt) Venus's atmosphere is mostly made up of :
a) carbon dioxide and oxygen
b) carbon dioxide and nitrogen
c) oxygen and nitrogen
d) sulfur
2.3. (1 pt) The Greenhouse Effect occurs when :
a) a planet's vegetation grows faster due to high temperatures
b) gas molecules reflect infrared radiation so the planet appears cooler than it is
c) gas molecules absorb, re-emit, and trap infrared radiation which heats the planet
d) a planet's atmosphere acts as a condensation shield, turning gas molecules into water
2.4. (1 pt) Earth's atmosphere is :
a) 78% oxygen; 21% nitrogen
b) 78% nitrogen, 21% oxygen
c) 50% oxygen; 50% carbon dioxide
d) 50% nitrogen; 50% oxygen
2.5. (1 pt) Mars' atmosphere is most like __________.
a) Earth's
b) Mercury's
c) Venus'
d) Jupiter's
2.6. (1 pt) Jupiter's atmosphere is made up of:
a) 90% hydrogen; 10% helium
b) 100% hydrogen
c) 90% hydrogen; 10% methane
d) 50% hydrogen' 50% helium
2.7. (1 pt) The Great Red Spot is
a) a large hurricane-like system in Jupiter's atmosphere
b) a large hole in Jupiter's atmosphere
c) a large crater on Jupiter
d) a large cloud in Jupiter's atmosphere
2.8. (1 pt) Saturn is made of hydrogen and helium and has a density
__________ water.
a) heavier than
b) lighter than
c) the same as
d) none of the above
2.9. (1 pt) In addition to hydrogen and helium, the atmosphere of Uranus
contains:
a) methane and sulfur
b) ammonia and argon
c) methane and ammonia
d) oxygen and methane
2.10. (1 pt) Neptune is like Uranus - being made of similar materials
and being _____ in color.
a) yellow
b) gray
c) green
d) blue-green
-------------------------------------------------
**EXPERIMENT**
Here we will examine some class photographs to learn more about planetary atmospheres.
Your TA has set up some class images #1 -9. Go to the demo table and answer these
questions:
2.11. (2 pts) Examine class Images #1 (Earth views) and #2 (Mars). For each,
list at least 2 pieces of evidence that indicate these planets have atmospheres.
2.12. (2 pts) Examine class Image #3 (Jupiter & Galilean moons). Explain how we know
from the image that both Io and Europa have reasonably thick atmospheres while Ganymede
has a very thin one and Callisto has only small traces of an atmosphere.
2.13. (4 pts) Examine class Images #4 (Jupiter & Great Red Spot), #5 (Saturn),
#6 (Uranus), and #7 (Neptune). Describe the "surfaces" of these planets (i.e., colors, textures,
features, etc.). How are they different from the terrestrial planet surfaces you examined
in "Planetary Geology"?
3.1. (3 pts) Using data from Table 1 in the lab text, calculate the
average temperature (TA) for Jupiter's atmosphere.
3.2. (3 pts) We observe the peak wavelength of Neptune's spectrum to
be λ = 5.79 x 10-5 m. Calculate the average
(blackbody) temperature
(TB) for Neptune.
This corresponds to a temperature of about –370 °F. One reason Neptune is so cold is because it is very far away from the Sun. Another reason is because it is comprised of methane gas (1.5%), water ice, and ammonia ice which at the high temperatures would no longer exist in gas form, eliminating the cloudy atmosphere.
3.3. (3 pts) Using the data from Table 1, calculate the atmospheric temperature (TA)
for Venus.
3.4. (3 pts) Now assume we obtained a spectrum of Venus with a peak wavelength in the IR region
(λ = 3.932 x 10-6 m). Calculate the observed blackbody temperature
(TB) for Venus.
3.5. (3 pts) How many times larger is Venus’ blackbody temp than its
atmospheric temp? Give a reason for this difference.
The reason that Venus has such an extremely high observed temperature is because Venus’ atmosphere is
about 96%
carbon dioxide gas which has taken the form of many thick, absorbant clouds. These clouds act
to shield gas and heat from escaping the atmosphere, and thus, Venus is experiencing a very severe case of
the Greenhouse effect (like on Earth). This phenomenon just traps heat below the cloud decks and heats its
surface quickly and efficiently, resulting in temperatures as
high as 750 K, or almost 900° Fahrenheit!
3.6. (1 pt) Name four physical properties of a planet that are related in
an atmospheric profile.
3.7. Examine and compare these atmospheric profiles.
a) (3 pts) What is the max temperature on Earth? On Mars? on Jupiter?
b) (4 pts) How are the profiles of these 3 planets alike? How are they
different? Give 2 examples for each.
-------------------------------------------------
**EXPERIMENT**
Make an atmospheric profile.
3.8. Here is some physical atmospheric data for the planet Saturn:
| ALTITUDE (km) | TEMP (°C) |
| -300 | 30 |
| -250 | 15 |
| -200 | -60 |
| -150 | -90 |
| -100 | -140 |
| -50 | -170 |
| 0 | -190 |
| 50 | -170 |
| 100 | -150 |
| 200 | -130 |
This corresponds to about 86 °F which is pretty warm. We also know that with Saturn's density, it could float in water. Therefore, it seems like a trip to Saturn would be just like a trip to Florida!
4.1. Use Table 1 in your lab text to calculate the escape speeds for the following planets.
[NOTE: you only need to show your work for part a; record only answers for part b - d]
a) (3 pts) vESC for Mercury
b) (1 pt) vESC for Earth
c) (1 pt) vESC for Jupiter
d) (1 pt) vESC for Pluto
To help you understand the concept of escape velocity for atoms and molecules on a planet, take a look at this webpage containing a series of 3 animations. To understand what's happening, scroll to each animation (gray window), read the caption, and press 'Start'. Now does it make sense why different planets have different atmospheres?
4.2. Now examine this graph and use it to answer the questions below.
a) (2 pts) Do heavier atoms and molecules need to have slower or faster
speeds in order to escape an atmosphere? Lower or higher temperatures?
b) (1 pt) Of the nine chemicals listed in this graph, which are found
in the Earth's atmosphere?
c) (1 pt) Mars’ atmosphere is 95.3% carbon dioxide, however, it also contains much rust-like dust.
Rust is a mixture of iron (heavier than xenon) and oxygen. Based on the above diagram, what
might happen to Mars’ atmospheric temperature if it were entirely
composed of this rust material?
d) (1 pt) A few Solar System moons are also marked on this graph - Ganymede, Titan, and Triton.
Do they appear to possess characteristics more similar to the outer or inner planets?
e) (1 pt) Why do you suppose it is that the inner planets like Mars and the
Jovian moons cannot retain the most universally abundant elements (hydrogen and helium) in
large quantities, while outer planets can?
4.3. Suppose we find there are 1.16 x 1013 deuterium
atoms and 7.25 x 1017 hydrogen atoms in the upper atmosphere of Saturn.
a) (3 pts) Calculate the [D/H] ratio for Saturn.
b) (1 pt) How does this compare to the primitive solar [D/H] abundance
estimates given in the lab text?
4.4. The values for Uranus are n(H) = 3.54 x 1017
atoms and n(D) = 3.398 x 1013 atoms.
a) (3 pts) What is the estimated [D/H] ratio for Uranus?
b) (2 pts) What can we conclude about the materials Uranus formed from
in relation to those involved in the formation of Saturn (see #4.3)? Give a reason to support your
answer.
-------------------------------------------------
**EXPERIMENT**
In this last exercise you will examine the spectra of the Jovian planets
to better understand how astronomers use spectroscopic analysis to learn about
the atmospheres of objects.
First, notice these two comparison spectra. They both
have several prominent spectral lines marked. You will compare these
standard spectra to those of Jupiter, Saturn, and Neptune to determine
some of the elements/molecules that make up the composition of each.
4.5. (5 pts) First, examine the two comparison spectra. There are
6 different spectral lines marked: for nitrogen (N2),
helium (He I), hydrogen (H I), water (H2O), and oxygen (O2).
There are also some methane (CH4) and ammonia (NH3)
spectral lines present that are not marked.
Below, fill in the blanks with the approximate wavelength for each of the 6
marked absorption lines.
Get as accurate as an answer as possible, i.e., to the nearest whole number.
For example, don't just guess 5500 Angstroms cause its nearby to that, but instead
write 5545 Angstroms because it is almost halfway between 5500 and 5550 Angstroms.
| ITEM | λ (Å) | λ (Å) | λ (Å) | λ (Å) | λ (Å) | λ (Å) |
| N2 | -------- | -------- | -------- | -------- | -------- | |
| He I | -------- | -------- | -------- | -------- | -------- | |
| H I | -------- | -------- | -------- | -------- | -------- | |
| H2O | 7023 / 7024 / 7030 | -------- | -------- | -------- | ||
| O2 | 7660 | -------- | -------- | -------- | -------- | |
| CH4 | 5449 / 5463 | 5930 | 6176 | 6200 / 6205 | 7262 | 7920 |
| NH3 | 6470 | 7917 | -------- | -------- | -------- | -------- |
4.6. (2 pts) Now, examine this spectra set for Jupiter.
Use the data in the table above to determine which molecules are found in Jupiter's atmosphere?
[NOTE: please record the molecule and its corresponding wavelength]
4.7. (2 pts) Now, examine this spectra set for Saturn.
Use the data in the table above to determine which molecules are found in Saturn's atmosphere?
[NOTE: please record the molecule and its corresponding wavelength]
4.8. (2 pts) Now, examine this spectra set for Neptune.
Use the data in the table above to determine which molecules are found in Neptune's atmosphere?
[NOTE: please record the molecule and its corresponding wavelength]
4.9. (2 pts) Review your results for the compositions of Jupiter, Saturn, and
Neptune (see #4.6 - 4.8). From this, what can we conclude about the Jovian planets as a whole?
4.10. (3 pts) List at least 3 reasons why the analysis of atmospheric profiles
and spectra are important in studying the formation and evolution of the Solar System.
Astronomy Home
Physics Home
| This web page created and maintained by Andrea Folcik |