78 terms

Astronomy 121

What is Rayleigh scattering, and what are its most noticeable effects for us on Earth?
The way light is scattered by air molecules and minute dust particles. The process by which radiation is absorbed then reradiated by the material through which it passes. Blue light has shorter wavelength. common effects are blue skys, red sunsets, and a sunburn in the shade.
What is the greenhouse effect, and what is its importance to the surface temperature of the Earth?
sunlight that is not reflected by clouds reaches the earths surface warming it up. infered radiaton reradiated from the surface is partially absorbed by the carbon dioxide in the atmosphere causing the overall temperature to rise.
What is convection, and how does it affect the Earth's atmosphere
convection is the consistant upwelling of warm air and the concurrent downward flow of cooler air to take its place. process that physically transfers heat from a lower (hotter) to a higher ( cooler) level. they combine to surface heating and surface winds, aka earths weather.
Explain how the Moon produces tides
direct result of the gravitational influence of the moon and sun on earth. because gravitational pull is stronger on the side nearest the moon we see higher tides then.
what would the moon look like if it had tides.
the rotation is syncryunus and its longated so the wave of water never moves. the bulge on earth follows the moon
f the Earth had no Moon, do you think we would know anything about tidal forces?
yes because we get the same effect from the sun.
s the greenhouse effect helpful or harmful for the Earth? Give examples. What would be the consequences of an enhanced greenhouse effect?
at the moment, helpful cause it makes our planet sustainable for life. Not too cold. Enhanced effects would make our planet much too warm and cause a runaway greenhouse effect.
By comparison with its average density, what do the densities of water and the Earth's crust tell us about the interior?
we know that the high central density suggests the earth must be rich in nickle and iron and that much of the core must be liquid.
Describe the Earth's magnetosphere, and describe how it was discovered.
the region around a planet that is influenced by that planets magnetic field. discovered by artifical sattellites launched in the 50's.
How does the Earth's magnetosphere protect us from the harsh conditions in interplanetary space?
the charged particales get trapped and become part of a belt. it traps what would be very violent towrds the human body.
How do geologists use earthquakes to map the Earth's interior?
by monotring p waves and s waves. by measuring the speed at which they travel through the earth can tell us the density.
Compare and contrast P-waves and S-waves, and explain how they are useful in geology.
p waves = pressure waves, like sound waves that expand and compress the medium through which they travel and can move through liquid. s waves = sheer waves and move along perendicular to the wave they travel.
Give two reasons for thinking the Earth's core is liquid.
it has a magnetic field and rotation as explained with the dynamo theory.
What does differentiation tell us about the Earth's history
it tells us that the earth was once molten and as a result the higher density matter sank and ligher twords surface. a heavy bombardment caused cooling and radioactive heating caused within caused interior to liquify.
How does convection affect the interior of the Earth?
it causes enormus forces that drag plates apart and push together in others.
How does radioactivity allow us to estimate the age of the Earth?
Radioactive or radiometric dating allows us to estimate the Earth's age by giving us the actual age of rock within a range of several million years. Radiometric dating is based on the scientific law of radioactive decay and the half-life of radioactive elements. Uranium and some other elements decay into lead over time at a specific rate. Knowing the content of these elements in the makeup of a rock allows its age to be calculated. Currently, the oldest rocks of Earth origin are estimated to be over 4 billion years old.
How did radioactive decay heat the Earth early in its history, and when did this heating end
it heated the earth by the release of energy in radio active particles. rock being a poor conductor of heat caused it to heat up interior . this process could have lasted billions of years but stopped when they ran out, as they can not be replenished.
What process is responsible for the large-scale features on the Earth's surface (mountains, oceanic trenches, and so forth)?
contential drift and plate tectonics, movement together makes mountains and separating causes trenches.
What conditions are needed for there to be a dynamo in the core of the Earth, and what does this dynamo produce?
you need convection, liquid core, and rotation. it produces a shift in the axis
How do we know that the Earth's magnetic field has reversed in the past, and what effect do you think these reversals may have had on life?
we know cause samples from the ocean floor reveal magnatism to have been oriented opposite from the current north south field. effect on animails will be confusing since they use it for their navigation but humans probably wont notice a thing.
How is the distance to the Moon most accurately measured?
parallax methods using earths diamater as a baseline
Employ the concept of escape speed to explain why the Moon has no atmosphere
the larger an object is the larger the speed needed to escape. moons escape speed is only 2.4 km/ s compared to 11.2 km/s earth
in was sense are the Lunar 'maria' seas?
the dark areas that look like oceans but are extensive flat areas resulting from lava flow. they are lower and come from the latin word for seas.
What is a synchronous orbit, and how did the orbit of the Moon come to be this way?
it is the condition in which the spin of one body is precisely equal to its revolution around another body. it is an inevitable consequense of gravitational inferaction. tidal bulge on moon from earth
What causes erosion on the Moon, and why is it slower than on Earth?
the moon lacks atmosphere and techtonic activity. so its only chance of ersion is collisions with other space objects.
What is the evidence that there is ice on the Moon?
radar echos found deposits of low density material probably water ice. the lunar prospecter mission confirmed the findings and detected large amounts.
Unlike the Earth, the surface of the Moon undergoes extreme temperature changes. Why?
becasue there is a lack of atmosphere to contain or deflect heat. the moon reaches 400k at noon but 100k at night and shade.
Describe a widely accepted theory of the Moon's origin.
the impact theory. a glancing blow with a mars sized object ( earth) caused a glob of earths mantle to break off. it explains the similarity to earths mantle and the lack of dense central core.
From a position on the Moon from which the Earth is visible, would the position of the Earth change in the sky over the course of a month? What changes in the appearance of the Earth would occur?
as the moon orbits the earth it keeps one face premantly pointed tword our planet. the earth would always be directly overhead.
What is a terminator line? What is the advantage of observing the terminator line on the surface of the Moon? If you were on a terminator line on the surface of the Earth, what time of day would it be?
fictious line that separates the light side from the dark side.
Where on the Moon would be the best place to make astronomical observations? What would be the advantages of this over observing from the Earth?
How is the varying thickness of the Moon's crust related to the presence or absence of maria?
result of lava flows during a much earlier period in earths history
Why is Mercury rarely seen with the naked eye?
cause of its closeness to the sun
Why did early astronomers think that Mercury was two separate planets?
because it is never far from the earth and only visible in dim light, thought to be the morning star and evening star.
Employ the concept of escape speed to explain why Mercury has no atmosphere
cause it is so much smaller than earth it has a littler atmosphere. its force on objects is greatly smaller and thus the escape speed being 4.2
Give two similarities and two differences between the surfaces of the Moon and Mercury
similar: cratered, highlands.
different: no lava flow, color, scarps
What does it mean to say that Mercury is in a 3:2 spin-orbit resonance? Why didn't Mercury settle into a 1:1 spin-orbit resonance with the Sun like the Moon did with Earth?
3 rotations for every 2 revolutions it cant fall into a 1:1 orbit cause of its eccentricity
What is a scarp? How are scarps thought to have formed? What is the basis for believing that the scarps on Mercury formed after most meteoritic bombardment had ended?
it looks similare to a fold mountain but it is caused by the shrinking of interior. they formed cause the interior cooled and shrunk much like the skin of an old apple. they cut across craters so we know it happned after.
Unlike the Earth, the surface of Mercury undergoes extreme temperature changes. Why?
result of eccentric orbit and spin orbit resonance
How is Mercury's evolutionary history similar to that of the Moon? How is it different?
similare cause of meteor bombardment and it has a thinner crust and more active volcanos
Explain why Mercury is never seen overhead at midnight in Earth's sky.
becasue it is always very close to the sun and you wouldnt see the sun overhead at midnight
Why does Venus appear so bright in the sky? On what does the brightness of a planet depend?
it is highly reflective due to dense atmosphere and is brightest when further away
Why is Venus always near the Sun in the sky?
cuase it is the second planet from the sun and its orbit lies with in earths
Why do astronomers think that the near resonance between Venus's rotation and orbit, as seen from Earth, is not really a resonance?
it would require it to be exactly 5 and not nearly 5.
Describe one observational problem associated with Venus's near resonance of rotation and orbit.
venus always presents the same face to earth at closest apporach
What is our current best explanation of Venus's slow, retrograde rotation?
its north pole is below the equator best explaination is that it was struck by a large body
If you were standing on Venus, how would the Earth look?
you wouldnt be able to see earth due to the cloud cover. but getting through it you would see a bright star
How did radio observations of Venus in the 1950s change our understanding of the planet?
helped us to undertand that its climate was like a desert rather than a tropical jungle.
How do the continents of Venus differ from Earth's continents?
it is only 8 % covering planet no large scale tectonics
What is the evidence for active volcanoes on Venus?
visivle lava flow there are corone and lava domes.
Given that Venus like Earth has a partially melted iron core, why doesn't it have a magnetic field like Earth's?
slow rotation causes a lack of the dynamo.
What did ultraviolet images returned by Pioneer Venus show about the planet's high-level clouds?
that they move at 400 km/h encircling the planet in just 4 days, faster than the planet its self rotates.
Name three ways in which the atmosphere of Venus differs from that of Earth.
90 times more massive than earth, extends higher, 90% lies w/in 10 km of se level on earth. the surface temp and pressure is at 50 km colder upper atmosphere.
What are the main constituents of Venus's atmosphere? What are the clouds in the upper atmosphere made of?
co2 and n2 clouds are made of sulfruic acid
What component of Venus's atmosphere causes the planet to be so hot? Explain why there is so much of this gas in the atmosphere of Venus compared with its presence in Earth's atmosphere. What happened to all the water that Venus must have had when the planet formed?
water vapor and co2 trap heat from sun. green house gasses cause so much of the co2
all water boiled off or combined
Earth and Venus are nearly alike in size and density. What caused one planet to evolve as an oasis for life, while the other became a dry and inhospitable world?
the run away greenhouse effect, venus greenhouse gases never left its atmosphere the way it did on earth. because venus is closer to the sun it is hotter and no oceans could condense and no where for the co2 to go.
f Venus had formed at Earth's distance from the Sun, what do you imagine its climate would be like today? Why do you think so?
you might think it would be cool enough for oceans to condense and for the atmosphre to be less pressured. it would be much more like earth
How do the impact craters on Venus differ from those on other bodies in the solar system?
they are much larger because its atmosphre is so big so only the much larger ones could break thorough
What is the evidence that volcanism of various types has changed the surface of Venus?
coronae and caldaras, lava domes and weak spots in the crust where lava flows up, fold mountains.
Do you think there might be life on Venus? Explain your answer.
I dont think so because it has an incredible atmospheric pressure that would sufficate any life with its lack of oxygen.
Do you think Earth is in any danger of a runaway greenhouse effect like that on Venus?
I think it is highly unlikely cause we would need incredible heat to boil off our oceans and for volcanic activity to slow down
Why is opposition the best time to see Mars from Earth?
because the earth lies between mars and the sun making us only . 37 au away.1. Mars is more than twice as far from the Sun, so its surface receives less sunlight.
2. The surface area of Mars is not that large, so there are fewer sq meters to intercept sunlight.
3. Mars is not very reflective.
Why are some Martian oppositions better than others for viewing Mars?
1. Mars is more than twice as far from the Sun, so its surface receives less sunlight.
2. The surface area of Mars is not that large, so there are fewer sq meters to intercept sunlight.
3. Mars is not very reflective.
How were the masses of Mars's moon measured, and what did these measurements tell us about their origin?
they were measured by the viking orbits and believed to be captured astroids
What are the Martian 'canals'?
they are deep cuts in the surface formed by plate tectonics
What is the evidence that Mars never melted as extensively as did Earth?
weak magnetic field, rapid rotation, implyes core is non metalic, lack of current volcanism, absance of any magnetic field, low density, high surface iron.
How would Earth look from Mars?
you would see phases
Why is Mars red?
cause there is a lot of iron on the surface and it mixes with the oxygen to produce a red rust color
hy are Martian volcanoes so large
cause there is lower sense of gravity they have less weight it has to support its self and the higher it can become
Describe the major large-scale features on the surface of Mars.
deep canyons, huge volcanoes, northern volvanic craters, southern hem is heavelity cratered
Describe the atmospheric conditions in the Southern Hemisphere of Mars during the summer.
temps of 300k and intense dust stomrs
Describe the two Martian polar caps - seasonal and permanent composition, and the differences between them.
they are composed mainly of co2 frost and vary on seasons growing and shrinking effects atmosphereic pressure. differ cause of eccentricity southern cap is bigger cuase its colder longer. top 3000 bot 4000
Why couldn't you breath on Mars?
atmosphere pressure is so low and is mainly co2
What is the evidence that water once flowed on Mars?
dry river beads, islands shaped from erision , flood channels, ejecta blankets impresion of liquid spashed or flowed
Is there liquid water on Mars today? Justify your answer.
it is frozen in layer under suface
What is the evidence that Mars once had an extensive ocean? Where was it?
erison on the foor of the holden crater near polar regions
Since the atmosphere of Mars is mainly the greenhouse gas carbon dioxide, why isn't there a significant greenhouse effect warming its surface?
because of its weak gravity and probably lost in colliosons. its lower volcanic activity rate thinned and cooled.
Compare and contrast the evolution of the atmospheres of Mars, Venus, and Earth.
earths stable green house effect venus overpowering and mars co2 may have desolved into rivers oceans and rocks with not enough volcanic activity to repenish it.