Chapter 15

Approximately how long does it take for the Sun to complete one rotation?

26 days

Which of the following statements about the Sun's photosphere is NOT TRUE? a. The photosphere is significantly hotter than all the layers of the Sun beneath it (further inward) b. The photosphere is not a solid layer; if a spaceship (that could withstand the heat) fell through it, it wouldn't feel anything when reaching the photosphere c. The photosphere is much less dense than our Earth's atmosphere d. The photosphere is the layer where the Sun becomes opaque (you can't see through it) e. Through a telescope, the photosphere looks mottled or granulated

a. The photosphere is significantly hotter than all the layers of the Sun beneath it (further inward)

Solar wind particles can be captured by the Earth's magnetosphere. When these particles spiral down along the magnetic field into the atmosphere, they are responsible for:

aurorae (northern and southern lights

What is the best reason astronomers have come up with to explain why sunspots are cooler and look darker? a. Sunspots are holes (less dense regions) in the Sun's photosphere, through which we can see the darker regions of the Sun below b. Sunspots are places where the strong magnetic fields in the Sun resist the upward motion of bubbling hot gases from underneath c. Sunspots are regions where carbon clouds high above the photosphere gather and these dark clouds block the light from underneath them d. Sunspots are regions in the upper chromosphere where there is a lot of coronium, which absorbs light e. Sunspots are so mysterious and difficult to explain, astronomers really don't have idea what causes them

b. Sunspots are places where the strong magnetic fields in the Sun resist the upward motion of bubbling hot gases from underneath

Astronomers have concluded that the Sun's activity varies in an 11-year cycle. Which of the following statements about this cycle is TRUE: a. Every 11 years sunspots completely cover the Sun, making its surface much darker Correct Response b. The number of sunspots gets larger and smaller over the course of 11 years c. When sunspots are at a minimum, we get the largest number of flares and prominences d. The Sun's activity cycle shows absolutely no connection to its magnetic field e. The Sun's activity cycle is directly connected to the number of earthquakes at the continental plate boundaries on Earth

b. The number of sunspots gets larger and smaller over the course of 11 years

Astronomers first detected the presence of a wind of particles coming from the Sun by

by noting the wind's effects on the tails of comets

A Canadian college student who has taken an astronomy class goes home for the holidays and persuades his parents to let him borrow the family car. When he returns, he finds that his parents are very angry with him, claiming he left the garage door open. Yet he remembers that he carefully closed the garage door with the electronic remote control in the car. After consulting with his astronomy instructor, he comes up with an alternative explanation for why the garage door is open. Which of the following is PART of that explanation? a. The Sun was so bright and high in the sky in December in Canada that it got into his parents' eyes b. There was an eclipse of the Sun c. It was a time of solar maximum, and there had been a big flare on the Sun earlier d. No aurorae had been seen in the sky for many months e. The number of sunspots had reached an all-time minimum

c. It was a time of solar maximum, and there had been a big flare on the Sun earlier

Which statement about the Sun's rotation is TRUE? a. The Sun does not rotate; only planets rotate b. The Sun rotates once a day c. The Sun rotates at different rates at different latitudes on the Sun d. The Sun rotates only at the equator, where the sunspots are found; the rest of the Sun does not rotate e. Only the atmosphere of the Sun rotates, not the main body of the Sun

c. The Sun rotates at different rates at different latitudes on the Sun

The hotter region directly above the Sun's visible surface is called the

chromosphere

The hottest zone in the Sun is the

core

Which part of the Sun's atmosphere has the lowest density (number of atoms per unit volume)?

corona

Which part of the Sun's atmosphere is the hottest?

corona

The ten million tons of particles that escape the Sun each year in the form of the solar wind get out mainly through regions called

coronal holes

Astronomers have found that the level of the Sun's activity varies over the centuries. How did they come to realize that this is so: a. historical records of the number of sunspots seen on the Sun b. measuring the amount of radioactive carbon in tree rings c. historical records of auroral activity Correct Response d. all of the above e. none of the above Submit Your Answer

d. all of the above

Which of the following statements about the violent events on the Sun called flares is FALSE? a. flares happen more often during solar maximum, and sometimes during those periods, there can be several in one day b. a flare can release energy equivalent to a million hydrogen bombs c. flares originate in the upper part of the corona, in the regions called coronal holes d. astronomers think that flares are connected with sudden changes in the magnetic field of the Sun e. the visible light we see from a flare is only a tiny fraction of the energy it releases

d. astronomers think that flares are connected with sudden changes in the magnetic field of the Sun

Coronal Mass Ejections from the Sun have many serious effects on or near the Earth. Which of the following is NOT one of these effects? a. disrupting the electronics of satellites b. heating the ionosphere and thus expanding the extent of our planet's atmosphere c. causing power surges and power outages in parts of the Earth near the poles d. causing huge cyclones around the equator of the Earth e. exposing astronauts and airplane passengers to increased amounts of radiation

d. causing huge cyclones around the equator of the Earth

As astronomers have learned more about the structure of the Sun, they have found that it a. has a small solid core inside b. is made entirely of liquid, with a tiny bit of hot gas on the outside c. is solid throughout, but with a large very hot atmosphere d. is made entirely of hot gas e. is made of billions of individual pieces of hot rock, all orbiting around each other in a whirling arrangement

d. is made entirely of hot gas

The Sun's chromosphere and corona were discovered

during total eclipses of the Sun

Which of the following is not part of some active regions on the Sun? a. sunspots b. flares c. plages d. prominences Correct Response e. granulation

e. granulation

Recently, some engineers and scientists have proposed building spaceships with enormous "sails" that catch the solar wind and use it to move the ship. What kinds of particles would be hitting this sail (i.e., what is the solar wind mostly made of):

electrons and protons

The granulation pattern that astronomers have observed on the surface of the Sun tells us that:

hot material must be rising from the sun's hotter interior

The most common element in the Sun is

hydrogen

Astronomers now realize that active regions on the Sun are connected with

loops of magnetic field emerging from the surface of the Sun

You are out on the beach, enjoying the warm sunshine with friends. As you glance up at the Sun (only briefly we hope), the part of the Sun that you can see directly is called its:

photosphere

When we use the light of atoms such as hydrogen and calcium to examine the Sun's outer layers, we can see bright "clouds" in the chromosphere right around the location of sunspots. These bright clouds are given the name:

plages

The Sun's chromosphere contains many jet-like projections that stick up into the transition region. These spikes of gas are called:

spicules

As you go upwards from the Sun's photosphere,

the density (number of atoms in a unit volume) decreases

How do astronomers know how strong the magnetic field of the Sun is?

the measure the Zeeman effect (the splitting of spectral lines)

The Sun's photosphere is

the part of the sun from which the light comes that we see when we look at the sun with our eyes

What mechanisms do astronomers believe is responsible for making the Sun's outer atmosphere so much hotter than its photosphere?

the sun's magnetic field interacting with the charged particles that make up the atmosphere

Sunspots are darker than the regions of the Sun around them because

they are cooler than the material around them (although still very hot compared to earth temperatures)

How do astronomers know what the outer layers of the Sun are made of?

we take an absorption line spectrum of the sun, and the absorption lines tell us what elements are present in the outer layers