Astro Test 3

Front 1

chemistry to biology

Back 1

1. organic soup of amino acids
2. short strands of RNA
3. spontaneous membranes --> "pre-cells"
4. pre-cell --> true living organisms
5. natural selection

Front 2

chemistry to biology step details
1. organic soup of amino acids

Back 2

has to be initial step, however amino acids formed
perhaps in special locations, not ubiquitous initially

Front 3

chemistry to biology step details
2. short strands of rna

Back 3

required help to initially assemble: clay or other minerals
RNA molecules might catalyze their own replication
initial simulation in the laboratory support this idea

Front 4

chemistry to biology step details
3. spontaneous membranes --> "pre-cells"

Back 4

protect chemicals and allow faster reactions

Front 5

chemistry to biology step details
4. pre-cell --> true living organisms

Back 5

heredity-machinery was simple
slow evolution through natural selection

Front 6

chemistry to biology step details
5. natural selection

Back 6

speeds up with increasing complexity of heredity-machinery
rapid increase in diversity likely due to introduction of DNA

Front 7

timeline
ss/earth formed

Back 7

4.55 billion yrs ago

Front 8

moon formed

Back 8

4.4 bya

Front 9

end of hadeon eon

Back 9

4.0 bya

Front 10

first isotopic evidence for life

Back 10

3.85 bya

Front 11

earliest microfossils

Back 11

3.5 bya

Front 12

beginning of proterozoic eon (rising oxygen levels)

Back 12

3.5 bya

Front 13

first eukarya fossils

Back 13

2.1 bya

Front 14

cambrian explosion

Back 14

550 million

Front 15

dinosaurs

Back 15

200 myr

Front 16

kt event

Back 16

65 mill

Front 17

modern humans

Back 17

100,000

Front 18

chemistry to biology step details
2. short strands of rna

Back 18

required help to initially assemble: clay or other minerals
RNA molecules might catalyze their own replication
initial simulation in the laboratory support this idea

Front 19

chemistry to biology step details
3. spontaneous membranes --> "pre-cells"

Back 19

protect chemicals and allow faster reactions

Front 20

chemistry to biology step details
4. pre-cell --> true living organisms

Back 20

heredity-machinery was simple
slow evolution through natural selection

Front 21

chemistry to biology step details
5. natural selection

Back 21

speeds up with increasing complexity of heredity-machinery
rapid increase in diversity likely due to introduction of DNA

Front 22

timeline
ss/earth formed

Back 22

4.55 billion yrs ago

Front 23

moon formed

Back 23

4.4 bya

Front 24

end of hadeon eon

Back 24

4.0 bya

Front 25

first isotopic evidence for life

Back 25

3.85 bya

Front 26

earliest microfossils

Back 26

3.5 bya

Front 27

beginning of proterozoic eon (rising oxygen levels)

Back 27

3.5 bya

Front 28

first eukarya fossils

Back 28

2.1 bya

Front 29

cambrian explosion

Back 29

550 million

Front 30

dinosaurs

Back 30

200 myr

Front 31

kt event

Back 31

65 mill

Front 32

modern humans

Back 32

100,000

Front 33

cambrian explosion 4 factors

Back 33

sudden rise in oxygen
significant increase in genetic complexity
climate: emerging from snowball earth episodes
no efficient predators

Front 34

photometry

Back 34

measure total amount of light from an object

Front 35

spectroscopy

Back 35

use a spectrograph to separate the light into its different wavelengths

Front 36

timing

Back 36

measure how the amount of light changes with time

Front 37

imaging

Back 37

filters are placed in front of a camera to allow only certain colors to be imaged
single color images are superimposed to form true color images

Front 38

spectroscopy can provide information on

Back 38

temperature
rotation rate
if atmosphere is present: atmospheric density, temperature, motions
chemical composition

Front 39

nonvisible light

Back 39

• Most light is invisible to the human eye.
• Special detectors/receivers can record such light.
• Digital images are reconstructed using false-color coding so that we can see this light.

Front 40

seeing through the atmosphere

Back 40

• Earth’s atmosphere causes problems for astronomers on the ground.
• Bad weather makes it impossible to observe the night sky.
• Air turbulence in the atmosphere distorts light.
o That is why the stars appear to twinkle
o Angular resolution is degraded.
• Man-made light is reflected by the atmosphere, thus making the night sky brighter.
o This is called light pollution

Front 41

atmospheric absorption of light

Back 41

• Earth’s atmosphere absorbs most types of light.
o Good thing it does, or we would be dead
• Only visible, radio and certain IR and UV light make it through to the ground

Front 42

4 pieces of evidence presented by scientists that ALH84001 preserves signs of past life on Mars

Back 42

o Carbonates: precipitated from thicker, warmer, atmosphere?
o Magnetite grains: similar in shape to bacterial magnetite?
o Complex organic molecules: PAHs
o Segmented, “bacterial” (?) morphologies

Front 43

IO

Back 43

• Most volcanically active place in whole SS
• Io dramatically shows the power of tidal heating
o Mostly rock now, no water (no life either…)
• For other moons, heating is more mild and may liquefy water ice

Front 44

angular resolution formula

Back 44

1.22(wavelength/diameter of telescope)

Front 45

key roles of water in creation of life

Back 45

1. provides more contact so organisms can react with each other
2. transportation: brings chemicals in and out of cells
3. participant in important reactions like ATP and photosynthesis

Front 46

Titan: Cassini View

Back 46

• Complex organics confirmed
• Radar and infrared imaging reveal complex surface geology, including streaks (from wind? Liquid? Ice?)
• Complex, dendritic patterns carved by liquid methane and shaped by topography. Some of the patterns imply rainfall; others could be liquid methane liberated from (?)

Front 47

habitable zone

Back 47

o The region in which temperatures would in principle allow for liquid water to exist on surface if a planet of the right type were located there.

Front 48

inner boundary

Back 48

• Inner boundary: distance where a planet will avoid a runaway greenhouse effect
o Somewhere between Earth and Venus
o Optimistic model: .84 AU would produce runaway greenhouse
o Pessimistic model: .95 AU- moist greenhouse

Front 49

outer boundary

Back 49

• Outer boundary: distance where even a strong greenhouse would not be warm enough to keep water as a liquid
o Optimistic model: thick atmosphere at 1.7 au (mars 1.52 au) would produce enough greenhouse effect
o Pessimistic model, 1.4 A/u: middle atmosphere too cold → CO2 snow ahhh changing slides!