Final Quiz

The total diameter of our galactic disk is about

100,000 light years

How far is it across the Milky Way Galaxy?

100,000 light years across

When was the Nuclear Test Ban Treaty signed, forbidding nuclear weapons in space?

1963

When did the Dutch-Italian satellite BeppoSAX first resolve the origin of a GRB?

1997

How long is the cylindrical bar of red stars at the center of our galaxy?

20,000 light years long.

How long does our Sun take to orbit the galaxy?

250 million years

We still classify galaxies according to Hubble's original system, based on

4 major types of galaxies.

Stars that could one day explode as gamma-ray bursts can only hurt us if they are

7000 light-years away.

How long did the gamma-ray bursts, detected by Vela, last?

A couple seconds.

What appears to be at the heart of every big galaxy we see?

A huge black hole.

What sits right at the center of many galaxy clusters?

A huge elliptical galaxy

The extremely high velocity orbits of stars at the center of our Galaxy are thought to be caused by what?

A supermassive black hole

Which of the following is not believed to be one of the components of our galaxy?

An active galactic nucleus (AGN)

What sort of geometry is believed to lead to Blazars, also known as BL Lacartae Objects?

An active galaxy where we happen to be right in line with one of the jets

What is the name of the other large galaxy in our galaxy group or cluster (not our galaxy)?

Andromeda

In the 1920's it was determined that the "Great Andromeda Nebula" was actually the

Andromeda Galaxy

Which of the following is a likely consequence of two galaxies colliding?

Both gas clouds collide and galaxies merge, but individual stars do not merge

Collisions between galaxies can

Cause bursts of star formation

Which distance method can be used to find the distance to nearby galaxies, such as Andromeda?

Cepheid variable stars

In the 1920's, what type of pulsating stars were observed in the spiral nebula M31?

Cepheid variables

What is believed to be the cause of the spiral structure in spiral and barred spiral galaxies

Density waves - the gravitational attraction of high density waves makes them self propagating

Which astronomers "unlocked the mystery" of spiral nebulae?

Edwin Hubble and Milton Humason.

Which shape are the largest galaxies in the Universe?

Elliptical

What type of galaxy is puffy, with no overall structure and populated with older stars?

Ellipticals

Which astronomer discovered that the Milky Way was actually made up of stars?

Galileo.

1. What "balls of stars" helped determine that the Sun wasn't at the center of the galaxy?

Globular clusters

Where are we, Earthlings, located in the Milky Way Galaxy?

Halfway out from the center in the suburbs

Which astronomer argued, in 1920, that "the Milky Way was all there is"?

Harlow Shapley

How many stars are in the Milky Way Galaxy?

Hundreds of billions of stars

What type of galaxy tends to be small and are truly shapeless?

Irregular galaxies

What image, taken in 1995, shows a small grain of the sky filled with thousands of galaxies?

It was a picture of the Hubble Deep Field.

The Vela satellites detected a mysterious flash of gamma rays on

July 2, 1967

Which of the following statements about the Milky Way's globular clusters is FALSE?

Like open clusters, Globular Clusters are found only in the Galaxy's disk

What name is given to the merger of the Milky Way and the Andromeda Galaxy?

Milkomeda.

What is the name of the galaxy we live in?

Milky Way

Which space observatory has detected and precisely located over 900 GRBs?

NASA's swift.

Within the disk of the galaxy, what sort of clusters of stars can typically be found?

Open clusters (only)

Our Sun is located just outside one of the smaller arms called

Orion Arm

What type of galaxy has a shape that's weird and distorted?

Peculiar galaxies

Spiral galaxies have spiral arms with a distinct bluish color, caused by what?

Recent and ongoing star formation

Sort the following three objects into size from smallest to largest

Solar System, Milky Way, Local Group

What type of galaxy is the Milky Way?

Spiral

At visible wavelengths, some regions of the Milky Way's disk appear dark because

Stars in that direction are obscured by interstellar dust

Clusters of galaxies themselves fall into even bigger groups called

Superclusters

Which telescope was used to search for evidence of black holes at the cores of galaxies?

The Hubble Space telescope

What is the biggest and most active star-forming gas cloud in any nearby galaxy?

The Large Cloud

Our Milky Way is part of a small knot of a few dozen galaxies that we call

The Local Group

The small cluster of galaxies to which the Andromeda galaxy belongs is

The Local Group

Our "hometown" is a vast, disk-shaped collection of stars called

The Milky Way Galaxy

Which two galaxies completely overpower the Local Group?

The Milky Way, and the Andromeda Galaxy.

Which two countries were the first to develop nuclear weapons?

The US and USSR

Why would we expect the bulge of a galaxy like ours to look redder than the disk?

The bulge consists mostly of old stars; the disk includes young stars

What object sits at the very center of our galaxy?

The bulge: spherical bar of redder stars

The predominant model of galaxy formation is

The hierarchical model, where small galaxies formed first and then merged into larger and larger galaxies

What makes the central part of our galaxy harder to study than in many other galaxies?

There is a lot of gas and dust between us and the center

Why are white dwarf supernovae such a useful distance method?

These are some of the brightest events in the universe, so you can see them at enormous distances

A property that is not generally true of spiral galaxies is

They are typically the largest type of galaxies (central dominant)

How many major spiral arms are in the Milky Way Galaxy?

Two

If viewed edge on, our galaxy would probably most resemble what shape?

UFO type shape

Our galaxy is especially difficult to observe than many other galaxies because

We are right in the plane of our galaxy, where the most gas and dust is

How can we possibly know what typical galaxies were like or what they were doing billions of years ago?

We can look at newly formed galaxies now, and assume that ancient galaxies looked the same when they were young

How can we typically measure how fast a galaxy is rotating?

We measure the Doppler shift of the 21 cm line from different parts of the galaxy

Which of the following is false about galaxy collisions?

When they collide, the stars in them often collide, destroying them

If the poles of an active galaxy are aimed right at us, we see energetic

X-ray and gamma-ray light.

The redshift of a galaxy is

a. How much redder the galaxy appears when observed at large distances b. The recessional velocity of a galaxy, expressed as a fraction of the speed of light

A massive star that explodes with more energy than a normal supernova is called an

accretion disk.

The flat disk of material that swirls around a black hole is called an

accretion disk.

Galaxies that emit x-rays and gamma rays were given the generic name

active galaxies

Often have radio jets extending from their cores, aligned with their minor axes

active galaxies

The spectrum of the Andromeda Galaxy is blue-shifted, which means it's

approaching us

Every time we see a gamma-ray burst, we're witnessing a

black hole being born.

Most large galaxies, including the Milky Way, likely grew to their current bulk by

consuming smaller galaxies

The mysterious bursts of gamma rays were determined to be coming from deep space.

deep space

Giant spheroidal galaxies typically having no apparent structure

ellipticals

In the 1960s, the peculiar object 3C273 was eventually determined to be an

entire galaxy

(T/F) Elliptical galaxies often have significant amounts of gas and dust

false

The patchy arms, that resemble tufts of cotton, in some spiral galaxies, are called

flocculent spirals

Current thinking is that elliptical galaxies are the products of

galactic collisions

One way to flip a quiescent black hole from a baby to a monster is through

galactic collisions

Massive objects revolving around each other lose orbital energy by radiating away

gravitational waves

The Vela satellites, launched by the US, were designed to detect

high-energy pulses of gamma rays.

There are two types of GRBs. The ones that last longer than two seconds come from

hypernovae

Early maps of the galaxy, which placed the Sun near the center, didn't account for

interstellar dust

Have very chaotic structure with no apparent symmetry

irregulars

The vast spherical cloud of old stars surrounding the Milky Way is called

its halo

For Cepheid variables, the time it takes them to pulse is directly related to their

luminosity

What is thought to be the source of energy in the nuclei of active galaxies?

massive black holes

Ancient Greeks called the glowing pathway in the sky "galaxius", which means

milky

Before 1920, "faint fuzzies" displaying a variety of shapes in the sky were simply called

nebulae

The cylindrical bar at the center of our galaxy is composed mostly of

old red stars

The most powerful energy source in the entire cosmos was dubbed, for short,

quasar

The words "irregular" and "peculiar" are used to classify galaxies based on

shape

GRBs were detected to be coming from galaxies as far away as

six billion light-years away.

Disks with central bulges surrounded by spherical halos of old stars

spirals

The spiral arms of our galaxy can best be thought of as

structures; huge collections of stars and nebulae moving together around the galaxy's center.

If GRBs were from neutron stars then we'd see them along

the plane of the milky way

(T/F) A spiral galaxy has both old and young stars

true

(T/F) When two galaxies merge, new stars are often formed in the process

true

The shorter GRBs that last only milliseconds come from

two neutron stars crashing into each other and exploding

10. Star-forming nebulae in spiral arms are colored pink by the characteristic glow of

warm hydrogen