Chapter 15 for Stars & Galaxies

The most common element in the Sun is

Hydrogen

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).

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.

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

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).

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 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

The Sun's chromosphere and corona were discovered

During the total eclipse 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 types of particles would be hitting this sail (i.e, what is the solar wind mostly made of)?

Electrons & 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 of the Sun are connected with

Loops of magnetic field emerging from the surface of the Sun

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

Plages

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

Spicules

What is 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.

As you go upwards from the Sun's photosphere,

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

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.

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 out eyes

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

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

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.