Assignment #10

Assignment #10 (1) Jupiter and Saturn vs. Uranus and Neptune We have compared the Terrestrial Planets and the Giant or Jovian Planets, but when we look at the 4 Giant Planets we can see that they can be paired into Jupiter and Saturn vs. Uranus and Neptune. (2 pts.) (1a) Explain 3 similarities shared by all 4 giant planets. All have outer rings. All have strong magnetic field. They all don’t have solid surfaces. (2 pts.) (1b) Explain 3 ways in which Uranus and Neptune differ from Jupiter and Saturn. Uranus and Neptune have ice mantles, while Jupiter and Saturn don’t have. Mostly Jupiter and Saturn are comprised of hydrogen and helium, while Uranus and Neptune are made of Methane. Uranus and Neptune are much smaller than Jupiter and Saturn. (2) Jupiter's Great Red Spot The GRS rotates completely in about five days. (3 pts.) If the spot is circular (not quite true, but a reasonable approximation for this matter) and 23,600 km in diameter, what are the wind speeds at the outer edges of the storm? Give you answer in km/hr. (Hints: Speed = distance÷time. How far does does a cloud on the edge of the spot move in one rotation? ) According to the condition above, the circumference of this circle is : 23600*pi  74141.59km, so 74141.59km/5days=14828.32km/day=14828.32km/24hours=617.85km/h

(3) Convince me! (4 pts.) We know that Saturn has a density less than that of water - so the planet would float in a giant bath tub. If you tell your friends that a planet could float, they are likely to laugh at you. Describe HOW we know the density of Saturn is less than that of water by observing it from here on Earth - what quantities have been measured (units?)? Which formula (or formulae) is (are) used? To figure out the density of the Saturn, according to the formula ρ = m V , we need to know both the mass of Saturn and volume of the Saturn separately. To determine the mass, we need to figure out the gravitational force that depends on the mass of Saturn and its moon: F grav = G M Saturn M moon r 2 , since the force is perpendicular to the momentum, the force will change the direction of the momentum and not the magnitude. So G M Saturn M moon r 2 also = M moon r ( 2 pi T ) 2 , so M Saturn = 4 pi 2 r 3 / GT 2 , to calculate this, we just need to measure the size of the orbit, the period of the orbit for its moon and the G, which is the universal gravitational constant. To determine the volume, according to: V = 4 3 pi R 3 , so we just need to measure the radius of the Saturn so that we can calculate the volume. (4) Layers upon layers. (5 pts.) Jupiter have several distinct layers of clouds. Why are these clouds separated into several distinct layers, so that clouds composed of a highly volatile gas such as ammonia found higher in the atmosphere than water? The reason these clouds are separated into several distinct layers is that different types of gases possess different densities, which form different layers by gravitational force. The ammonia is found higher in the atmosphere than water is due to the lower density of the ammonia gas, which result in precipitation of water with high density to the bottom, compared to the ammonia gas.

explain exactly how each would account for why they would differ so much in their quantities of atmosphere. Hypothesis 1: Due to the stronger gravity, the planet with larger atmosphere can keep more gases above the planet than the planet with less atmosphere. Hypothesis 2: Due to the stronger magnetic field, the planet with larger atmosphere can maintain high gas level without being stripped away from the planet, compared to the planet with less atmosphere. Hypothesis 3: Due to the active volcanic activities on the planet, the planet with larger atmosphere can generate more gas than the planet with less atmosphere. (5 pts.) (8 b) Our solar system contains 4 terrestrial planets and 4 jovian planets. Suppose we discover another solar system with 8 planets that all orbit at their star at the same distances of the 8 planets in our own solar system, however these are all terrestrial planets and there are no jovian planets. Propose a hypothesis to explain why the formation of that solar system would have turned out so differently from our own. During the formation of these planets among this new solar system, there was not enough heavy, dense particles to aggregate and form a planet with relatively small but dense core, so these planets can’t be surrounded by massive layer of gas like hydrogen and helium. (4 pts.) (8 c) Why would astronomers be surprised to discover an active volcano on an asteroid? Volcanism is the result of the eruption of molten rock on the surface of a planet. The asteroid is usually too small to have a core, which is hardly to form volcanoes in theory.