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ASTR1000 University of Colorado Solar System Cloud & Bands Questions

    (1) Pluto

    (5 pts.) Why don’t astronomers consider Pluto to be a major planet anymore? Write a paragraph giving a careful and thorough scientific explanation.

    (2) Motions in the Solar System

    (6 pts.) Explain the theory that we have which explains why the planets all orbit the sun in circular orbits, going the same direction in a flat disk.

    (3) Cloud Bands

    (5 pts.) Astronomers discover a planet orbiting around another star. The star is very much like our Sun, and the planet is almost a twin to Jupiter. The planet has the same mass as Jupiter, is the same distance from its star as Jupiter is from our Sun (5.2 AU), has the same orbital period (12 years), is the same temperature, and has the same density and chemical composition as Jupiter. However, when we take a close up picture of the planet, we find that its clouds are not lined up in East/West bands like Jupiter. Instead the clouds appear to randomly swirl around. Propose a hypothesis to explain why this planet’s clouds would not be organized into East/West bands like we see on Jupiter.

    (4) Meteorite Ages

    (5 pts.) When meteorites fall to the earth, we can sometimes measure the ages by studying the amounts of different radioactive elements that they contain, in pieces called “calcium-aluminum-rich-inclusions”. The oldest known meteorites are slightly less than 5 billion years old. Suppose that in the future, we use radiometric dating on a meteorite and find that it is 7 billion years old. To explain this unusually large age, someone proposes: “Perhaps this meteorite is from another galaxy.” Evaluate this proposal. Does this hypothesis make sense? Write a few sentences explaining why or why not. If not, propose a similar but more reasonable hypothesis.

    (5) Time scale for the solar system.

    In this question we construct a scale model for the solar system, similar in principle to the scale models that can be found at most planetariums or science museums. Instead of scaling DISTANCE we are scaling TIME. The idea is to get a sense of relative times between important solar system events. We use Boulder as a sample location – but you could pick any where).
    (2 pts.) (a) Take the average American lifespan of about 80 years to be scaled down to 1 second. What does this make our scale factor? That is, how many seconds are there in 80 years? This is the amount we will be speeding up time (or scaling down time scales).
    (2 pts.) (b) So, in our scale model for the solar system, a lifespan of 80 years is 1 second ago. Using the same scale factor, how long ago was the town of Boulder founded? Let’s use 1860, the year when the Wellman brothers planted the first wheat crop in Boulder County, and the year when the first schoolhouse in Colorado built strictly for educational purposes was erected in Boulder on the southwest corner of 14th and Front [Walnut]. In our model, how many seconds ago were these events?
    (1 pt.) (c) If we guess that native americans were in Boulder about 10,000 years ago, how long ago is that in our scaled model? (For this and the following questions, please convert your answer to minutes, days, or years — whichever is most appropriate. It’s much more useful to say 8.3 minutes than 500 seconds!)
    (1 pt.) (d) The Flatiron Mountains were formed about 40 million years ago. Use the scale factor to find how long ago that is in our scale model for time scales of the solar system.
    (1 pt.) (e) Dinosaurs hung around Boulder about 120 million years ago – what’s this scale to?
    (1 pt.) (f) Fossils tell us that life first existed on land about 400 milion years ago – those are the fish that flopped about and learned to breath air – put that date on scale model.
    (1 pt.) (g) The earliest life is thought to have appeared on Earth about the time of the end of the period of heavy bombardment of the planets (when the cratering slowed down). This makes sense, doesn’t it, that the slime and creepy-crawlies would have a hard time surviving until the aerial bombing ceased – that was about 3.8 BILLION years ago. What does that scale to?
    (1 pt.) (h) Calculate the scaled time for the formation of the Earth,4.6 billion years ago.
    (1 pt.) (i) Finally, calculate the scaled time for the big bang, the formation of our universe 13.7 billion years ago

    (6) Orbits, Shepherding, and Resonance
    (2 pts.) (a) In the context of planetary rings, explain how shepherding works. Why do you need two moons on either side of a ring in order to hold it in place?
    (2 pts.) (b) How did orbital resonance lead to the formation of the Kirkwood gaps in the asteroid belt?
    (4 pts.) (c) Suppose that we have a small ice particle that orbits Saturn every 5 hours, and suppose that there is a moon out farther from Saturn that orbits once every 15 hours. How will that moon affect this ice particle? What will be the end result of this relationship?

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