21st Century Astronomy Chapter 07

The dependence of planetesimal composition on distance from the Sun and the existence of the frost line resulted in two main types of planets in our Solar System: the inner rocky planets and the outer gas giants. The gas giants are observed to be made mostly of hydrogen and helium.Given this observation and what you have learned about planetesimal formation through accretion, and the types of materials that condensed at that distance from the Sun, which of the following is the most likely way that the gas giants formed?Choose one:A. They must have formed elsewhere and been captured by the Sun's gravity because hydrogen and helium could not condense into a solid at the temperature of the Solar Nebula.B. Hydrogen and helium condensed into a solid and accreted to form the gas giants.C. Rock, metal, and ices made of materials like water, ammonia, and methane condensed into a solid and grew large enough to gravitationally attract hydrogen and helium gas from the Solar Nebula.

C. Rock, metal, and ices made of materials like water, ammonia, and methane condensed into a solid and grew large enough to gravitationally attract hydrogen and helium gas from the Solar Nebula.

Clumps grow into planetesimals by Choose one:A. conserving angular momentum.B. gravitationally pulling in other clumps.C. colliding with other clumps.D. attracting other clumps with opposite charge.

C. colliding with other clumps.

Given what you learned in the video, why do we find rocky material everywhere in the Solar System, but large amounts of volatile material only in the outer regions? Choose one:A. The decreased energy in the inner region allows only rocky material to exist.B. The increased gravity in the inner regions destroys the volatile material.C. The outer regions of the Solar System are moving less.D. The outer regions of the Solar System are cooler.

D. The outer regions of the Solar System are cooler.

The diagram shown illustrates the location of the Solar System's eight planets and three large dwarf planets. Sort each object according to its basic composition.

Gaseous: Jupiter, Saturn, Uranus, Neptune Rocky: Mercury, Venus, Earth, Mars, Ceres Rocky/Ice: Pluto, Eris

Apply everything you have learned to match the patterns of planetary properties in our Solar System to the physical law or process that best explains their existence, given that the planets were formed from a spinning cloud of collapsing gas and dust. Drag and drop to match the pattern (4 items) to the corresponding law or process (A to D) below.A = More massive objects will collide with or fling more objects away during gravitational close encounters.B = More materials could condense farther from the Sun.C = Conservation of angular momentumD = Collisions will remove random orbits of particles.

A. The planets closest to the Sun are much closer to each other than the planets that are farther away B. The planets closest to the Sun are much smaller than the planets that are farther away C. All planets orbit the Sun in a roughly flat plane D. All planets orbit the Sun in the same direction

If a quantity is conserved, it means that it Choose one:A. it doesn't change. B. changes only if an external force acts.C. changes only if an internal force acts.D. can be saved for a later time.

A. it doesn't change.

Imagine that a star-forming cloud collapses but retains all of its mass in a single blob. In order to conserve angular momentum, the cloud must Choose one:A. spin faster.B. spin slower.C. come to a complete stop.D. spin at the same rate.

A. spin faster.

Comparative studies of objects in a group help us learn more about those objects than we could learn by studying each object individually. With this goal in mind, watch this video, and select all of the following choices that describe your observations of patterns. As you do so, think about the implications of how the Solar System may have formed.Choose one or more:A.The planets closest to the Sun are much smaller than the planets that are farther away.B.The size of all planets increases with distance from the Sun.C.All planets orbit the Sun in the same direction.D.Planets orbit the Sun in random directions.E.Planets are evenly distributed in distance from the Sun.F.All planets orbit the Sun in a spherical distribution.G.All planets orbit the Sun in a roughly flat plane.H.The outer planets (those farthest from the Sun) are spaced farther apart from one another than the inner planets are spaced.

A.The planets closest to the Sun are much smaller than the planets that are farther away. C.All planets orbit the Sun in the same direction. G.All planets orbit the Sun in a roughly flat plane.H.The outer planets (those farthest from the Sun) are spaced farther apart from one another than the inner planets are spaced.

Why is it so difficult for astronomers to take a picture of an extrasolar planet? Choose all the correct answers. Choose one or more:A.Astronomers do not know where to aim their imaging equipment.B.Stars are so distant that they appear only as point sources, and their planets aremuch smaller than the stars themselves.C.The light from the planet is redshifted so far that current detectors cannot see it.D.Extrasolar planets move too quickly in their orbits for stable imaging.E.Planets are fainter than their stars and cannot be seen in the glare of starlight.

B.Stars are so distant that they appear only as point sources, and their planets are much smaller than the stars themselves. E.Planets are fainter than their stars and cannot be seen in the glare of starlight.

Study the size difference of the gas giants as shown in the above image (distance from the Sun increases from left to right), and choose the best explanation below for your observations.Choose one:A. Gas giants increase in size with increased distance from the Sun because the Solar Nebula was denser farther out.B. Gas giants decrease in size with increased distance from the Sun because fewer types of materials could condense farther out.C. Gas giants decrease in size with increased distance from the Sun because the Solar Nebula was less dense farther out.D. Gas giants increase in size with increased distance from the Sun because more types of materials could condense farther out.

C. Gas giants decrease in size with increased distance from the Sun because the Solar Nebula was less dense farther out.

Rank the following events in the order that corresponds to the formation of a planetary system.

1. Gravity collapses a cloud of interstellar gas 2. A rotating disk forms & dust grains stick together by static electricity 3. Small bodies collide to form larger bodies 4. Primary atmospheres form 5. A stellar wind "turns on" and sweeps away gas and dust, removing primary atmopsheres from planets 6. Secondary atmospheres form