Florida National University Fusion Reactions Questions

4 PointsWhere in the Sun do fusion reactions happen?

1. everywhere inside the Sun
2. core and radiation zone
3. only the core

4 PointsThe corona and chromosphere are hotter than the photosphere.

1. True
2. False

4 PointsHow does the Sun’s mass compare to Earth’s mass?

1. The Sun’s mass is about 30 times the mass of the Earth.
2. Both have approximately the same mass.
3. The Sun’s mass is about 300,000 times the mass of the Earth.
4. The Sun’s mass is about 300 times the mass of the Earth.

4 PointsThe temperature of the Sun’s core is about 20,000 K.

1. True
2. False

4 PointsThe core of the Sun is

1. constantly rising to the surface through convection.
2. much hotter and much denser than its surface.
3. composed of iron.
4. at the same temperature but much denser than its surface.
5. at the same temperature and density as its surface.

4 PointsThe chromosphere is the layer of the Sun that we see as its visible surface.

1. True
2. False

4 PointsWhich is closest to the temperature of the Sun’s core?

1. 100,000 K
2. 10 million K
3. 10,000 K
4. 1 million K
5. 100 million K

4 PointsWhich of the following correctly describes how the process of gravitational contraction can make a star hot?

1. Gravitational contraction involves nuclear fusion, which generates a lot of heat.
2. Gravitational contraction involves the generation of heat by chemical reactions, much like the burning of coal.
3. When a star contracts in size, gravitational potential energy is converted to thermal energy.
4. Heat is generated when gravity contracts because gravity is an inverse square law force.

4 PointsBy what process does the Sun generate energy?

1. chemical reactions
2. nuclear fusion
3. gravitational contraction
4. nuclear fission
5. gradual expansion

4 PointsAlthough the Sun does not generate energy by gravitational contraction today, this energy-generation mechanism was important when the Sun was forming.

1. True
2. False

4 PointsWhat is the diameter of the disk of the Milky Way?

1. 1,000 light years
2. 10,000 light years
3. 100,000 light years
4. 1,000,000 light years
5. 100 light years

4 PointsWhat do we mean by the interstellar medium?

1. the name of an oracle who can channel messages from beings that live near the star called Vega
2. the gas and dust that lie in between the stars in the Milky Way galaxy
3. the dust that fills the halo of the Milky Way galaxy
4. the middle section of the Milky Way galaxy

4 PointsThe Sun is located near the edge of our galaxy, approximately 100,000 light-years from the galactic center.

1. True
2. False

4 PointsHow does the diameter of the disk of Milky Way Galaxy compare to its thickness?

1. The diameter is about 100,000 times as great as the thickness.
2. The diameter is about 100 times as great as the thickness.
3. The diameter and thickness are roughly equal.
4. The diameter is about 10 times as great as the thickness.

4 PointsOn a dark summer night in the northern hemisphere, we can see the Milky Way, but we can’t see the center of the Milky Way. Why not?

1. The center of the Milky Way does not emit enough visible light.
2. There are no stars in the center of the Milky Way, just a supermassive black hole.
3. Interstellar dust and gas absorb and scatter visible light.
4. We are in the center of the Milky Way.

4 PointsWhat kinds of objects lie in the halo of our galaxy?

1. globular clusters
2. open clusters
3. All of these
4. O and B stars
5. gas and dust

4 PointsHow do we know the total mass of the Milky Way Galaxy that is contained within the Sun’s orbital path?

1. by using the law of conservation of angular momentum to calculate the orbital speeds of nearby stars
2. by counting the number of stars visible in this region of the galaxy
3. by applying Newton’s version of Kepler’s third law (or the equivalent orbital velocity law) to the Sun’s orbit around the center of the Galaxy
4. by estimating the amount of gas and dust in between the stars

4 PointsWhat do we call the bright, sphere-shaped region of stars that occupies the central few thousand light-years of the Milky Way Galaxy?

1. the galaxy’s halo
2. the galaxy’s disk
3. a globular cluster
4. the galaxy’s bulge

4 Points This diagram represents an edge-on view of our Milky Way Galaxy. Of the four labeled stars, which one is located in what we call the halo of the galaxy?

1. 4
2. 3
3. 2
4. 1

4 PointsMost stars in the Milky Way’s halo are ________.

1. very old
2. very young
3. found inside molecular clouds
4. blue or white in color

4 PointsWhere does most star formation occur in the Milky Way today?

1. uniformly throughout the Galaxy
2. in the bulge
3. in the Galactic center
4. in the spiral arms
5. in the halo

4 PointsWhat do halo stars do differently from disk stars?

1. They remain stationary, quite unlike disk stars that orbit the galactic center.
2. They orbit the center of the galaxy at much lower speeds than disk star.
3. They orbit the galactic center with many different inclinations, while disk stars all orbit in nearly the same plane.
4. Halo stars explode as supernovae much more frequently than disk stars.

4 PointsWhy do sunspots appear dark?

1. They are regions nearly devoid of gas.
2. They are composed of different elements than the rest of the sun.
3. They are thick clouds on the sun, blocking its light.
4. They are regions that are significantly cooler than the rest of the photosphere.

4 PointsHow is the sunspot cycle directly relevant to us here on Earth?

1. The sunspot cycle is the cause of global warming.
2. The brightening and darkening of the Sun that occurs during the sunspot cycle affects plant photosynthesis here on Earth.
3. The Sun’s magnetic field, which plays a major role in the sunspot cycle, affects compass needles that we use on Earth.
4. Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.
5. The sunspot cycle strongly influences Earth’s weather.

4 Points The dark spots in this photo (such as the one indicated by the arrow) represent what we call:

1. Great Dark Spots
2. sunspots
3. solar prominences
4. coronal holes
5. none of the above