Stars and Galaxies Chapter 15

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:

>all of the above historical records of the number of sunspots seen on the Sun historical records of auroral activity measuring the amount of radioactive carbon in tree rings

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)

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

Chromosphere

Which of the following is not part of some active regions on the Sun?

Granulation

The most common element in the Sun is

Hydrogen

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?

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

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:

Plagues

What is the best reason astronomers have come up with to explain why sunspots are cooler and look darker?

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

Which statement about the Sun's rotation is TRUE?

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

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.

Astronomers have concluded that the Sun's activity varies in an 11-year cycle. Which of the following statements about this cycle is TRUE:

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

Which of the following statements about the Sun's photosphere is NOT TRUE?

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

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

We take an absorption line spectrum of the Sun. These absorption lines tell us what elements are present in the outer layers.

Which of the following statements about the violent events on the Sun called flares is FALSE?

astronomers think that flares are connected with sudden changes in the magnetic field of the sun

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

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?

causing huge cyclones around the equator of the Earth

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

The Sun's chromosphere and corona were discovered

during total eclipses of the Sun

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

As astronomers have learned more about the structure of the Sun, they have found that it

is made entirely of hot gas

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

loops of magnetic field emerging from the surface of the Sun.

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

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

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 how strong the magnetic field of the Sun is?

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