What evidence do we have that the granulation seen on the sun's surface is caused by convection?

1. What effect does the formation of negative hydrogen ions in the sun's photosphere have on solar observations? • We can view the sun's interior through special filters set to the wavelength of the absorption lines created by such ions. • Concentrations of such ions form sunspots that allow us to track solar rotation. • It divides the sun's atmosphere into three distinct, easily observable layers. • The extra electron absorbs different wavelength photons making the photosphere opaque. • These ions produce the "diamond ring" effect that is seen during total solar eclipses.

2. What evidence do we have that the granulation seen on the sun's surface is caused by convection? • The bright centers of granules are cooler than their dark boundaries. • The bright centers of granules are hotter than their dark boundaries. • Doppler measurements indicate that the centers are rising and edges are sinking. • The bright centers of granules are cooler than their dark boundaries; and Doppler measurements indicate that the centers are rising and edges are sinking. • The bright centers of granules are hotter than their dark boundaries; and Doppler measurements indicate that the centers are rising and edges are sinking.

3. Which layer of the sun's atmosphere contains the cooler low-density gas responsible for absorption lines in the sun's spectrum? • photosphere • chromosphere • corona • solar wind • all of these choices

4. Which of the following is true about granules and supergranules? • They are both about the same size. • Granules and supergranules each fade in about 10 to 20 minutes. • They are both due to convection cells in layers below. • They are both about the same size; and They are both due to convection cells in layers below. • Granules and supergranules each fade in about 10 to 20 minutes; and They are both due to convection cells in layers below.

5. This diagram explains the structure of solar granules. Why is the center of a granule brighter than its edges? • The surface elevation is higher at the center. • The surface elevation is lower at the center. • The temperature is higher at the center. • The temperature is lower at the center. • The surface elevation is higher at the center; and The surface elevation is lower at the center.

6. What is revealed by observing the sun at a very narrow range of wavelengths within the 656-nm hydrogen alpha line? • the structure of the photosphere • the structure of the chromosphere • the structure of the corona • We can see the electrons make the transition from energy level 3 to level 2. • Nothing is seen; all light is absorbed at this wavelength.

7. The sun’s atmospheric layers are all less dense than its interior. Based on this figure, which layer of the sun is responsible for the absorption lines in the solar spectrum? • corona • chromosphere • photosphere • All the layers are responsible. • both corona and chromosphere

8. What are the general trends in temperature and density from the photosphere to the chromosphere to the corona? • The temperature increases and density decreases. • The temperature increases and density increases. • The temperature decreases and density decreases. • The temperature decreases and density increases. • The temperature and density remain constant.

9. What physical property of the sun is responsible for "limb darkening"? • The chromosphere is hotter than the photosphere. • The chromosphere is cooler than the photosphere. • The lower photosphere is cooler than the upper photosphere. • The lower photosphere is hotter than the upper photosphere. • The chromosphere is hotter than the photosphere; and the lower photosphere is hotter than the upper photosphere.

10. The spectrum of the corona has bright spectral lines of highly ionized elements. What does this reveal? • The corona is a very hot, high-density gas. • The corona is a very hot, low-density gas. • The corona is very irregular in shape. • The corona extends out to 20 solar radii. • The corona is a very hot, low-density gas; and the corona extends out to 20 solar radii.

11. What heats the chromosphere and corona to high temperatures? • long-wavelength electromagnetic radiation emitted by layers below • visible light emitted by layers below • short-wavelength electromagnetic radiation emitted by layers below • sun-grazing comets giving up their energy of motion as they vaporize in these two layers • fluctuating magnetic fields from below that transport energy outward

12. How are astronomers able to explore the layers of the sun below the photosphere? • Short-wavelength radar pulses penetrate the photosphere and rebound from deeper layers within the sun. • Long-wavelength radar pulses penetrate the photosphere and rebound from deeper layers within the sun. • Highly reflective space probes have plunged below the photosphere and sampled the sun's interior. • By measuring and modeling the modes of vibration of the sun's surface. • By observing solar X rays and gamma rays with space telescopes. These shorter wavelengths are emitted from hotter regions below the photosphere.

13. What is responsible for the sun's surface and atmospheric activity? • the sun's magnetic field • many comets impacting the sun • gravitational contraction of the sun • the sun sweeping up interstellar space debris • gravitational interactions between the sun and the planets

14. Each of these frames shows the migration (due mostly to solar rotation) of sunspots across the face of the sun with the earliest sketch at the top. If the north pole of the sun is at the top of each frame, in which direction does the sun rotate? • clockwise when viewed from above the sun’s north pole • counterclockwise when viewed from above the sun’s north pole • It depends on which part of the solar cycle the sun is in. • The sun does not rotate. The effect is due to the rotation of Earth. • none of these choices

15. What is the source of the sun's changing magnetic field? • the differential rotation of the sun • convection beneath the photosphere • the sun's large iron core • the differential rotation of the sun; and convection beneath the photosphere • the differential rotation of the sun; and the sun's large iron core

16. What evidence do we have that sunspots are magnetic? • The spectral lines of sunspots are split by the Zeeman Effect. • Observations show that the north pole and south pole sunspots attract one another and move closer together over time. • Observations at far ultraviolet show material arched above the sun's surface from one sunspot to another. • The spectral lines of sunspots are split by the Zeeman Effect; and observations show that the north pole and south pole sunspots attract one another and move closer together over time. • The spectral lines of sunspots are split by the Zeeman Effect; and observations at far ultraviolet show material arched above the sun's surface from one sunspot to another.

17. Which active feature in the sun's atmosphere, seen from a different point of view, corresponds precisely to the dark filaments that are observed with a hydrogen alpha filter? • sunspot • solar flare • prominence • spicule • coronal hole

18. What does a Maunder butterfly diagram show? • During the 11-year sunspot cycle, the spots begin at high latitude and then form progressively closer to the equator. • Between the years 1645 and 1715, the low activity on the sun correlates with the Little Ice Age. • The sun's magnetic field is simple at the beginning of a sunspot cycle and grows progressively more complex due to differential rotation. • Planetary nebulae do not all have spherical symmetry. • When a butterfly flaps its wings in Brazil, it affects the climate worldwide.

19. How constant is the solar constant? That is, by how much has the solar constant of 1360 joules per square meter per second been observed to vary over days or weeks? • about 20% • about 10% • about 5% • about 1% • about 0.1%

20. How does the sun maintain its energy output? • gravitational contraction • fusion of hydrogen nuclei • the impact of small meteoroids • coal burning in pure oxygen • fission of uranium 235

21. Why does nuclear fusion require high temperatures? • Protons have positive charge, and like charges repel one another. • Two protons must get close enough together to overcome the Coulomb barrier. • Two protons must get close enough for the strong force to bind them together. • Protons have positive charge, and like charges repel one another; and two protons must get close enough together to overcome the Coulomb barrier. • all of these choices

22. Based on this figure, which atomic element has the greatest binding energy per nuclear particle? • hydrogen • helium • carbon • iron • uranium

23. What happens to the neutrinos that are produced in the proton-proton chain? • They collide immediately with other particles, thus adding to the gas pressure that supports the sun against gravitational contraction. • They combine with antineutrinos and form a pair of gamma rays. • They head out of the sun at nearly the speed of light. • They are blocked by the Coulomb barrier and remain inside the sun. • They spiral out along magnetic field lines to become cosmic rays.

24. What solved the solar neutrino problem? • The discovery that neutrinos oscillate between three different types. • The standard model of energy production within the sun was modified. • It was discovered that electron neutrinos do not penetrate rock as easily as expected. • Some of the radioactive argon gas was found leaking out of the neutrino detector undetected. • The finding that chlorine does not interact with electron neutrinos as predicted.