THE SOUTHWORTH PLANETARIUM
207-780-4249 www.usm.maine.edu/planet
70 Falmouth Street Portland, Maine 04103
43.6667° N 70.2667° W
Founded January 1970
Julian date: 2457677.16
"Safe journey, space fans, wherever you are."
-Stephen Hill, Producer and Host of "Music from the Hearts of Space"
THE DAILY ASTRONOMER
Friday, October 14, 2016
Quiz VII : Our Home Galaxy
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A SACRED SOUND JOURNEY INTO SPACE
A Gong Concert by Todd Glacy
Sunday, October 16 at 6:00 p.m
at the Southworth Planetarium.
Tickets still available.
For more information:
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Galaxies: the cosmic building blocks. A hundred years ago, humanity believed that our home galaxy defined the extent of the Universe. Now, we know that this galaxy is but one of hundreds of billions. That which we presumed to comprise the entirety of the known cosmos has been reduced in scope almost to negligiblity. Today, however, we celebrate our home galaxy, while giving some mention to those within its proximity.
1. In which galaxy do we live?
a. Andromeda
b. Milky Way
c. Sagittarius Dwarf
d. We technically don't live in a galaxy
2. Our galaxy is classified as a _________________
a. barred spiral
b. regular spiral
c. elliptical
d. a candy bar that would taste a lot better if it had nuts in it.
3. Our solar system is located in a region of the galaxy named _________________
a. the Sagittarius-Carina Arm
b. the Orion-Cygnus Arm
c. the Perseus Arm
d. the Scutum-Centaurus Arm
Galactic nuclei contain supermassive black holes. Questions 4 -5 pertain to this supermassive black hole.
4. What is the name of the black hole in our own galactic nucleus?
a. It doesn't have a name.
b. Cygnus X-1
c. Sagittarius A
d. HSR 112435 smbh
5. How massive is the black hole at the galaxy's center?
a 4.5 million times more massive than the Sun
b. 100 million times more massive than the Sun
c. 250 million times more massive than the Sun
d. 1.2 billion times more massive than the Sun
6. A galactic year equals the time required for our solar system to complete one orbit around the galaxy. Approximately how long is a galactic year in terms of Earth years?
a. 100,000 years
b 10 million years
c. 225 million years
d. 1.2 billion years
7. Our galaxy measures about ________________ light years along its diameter.
a. 23,000
b. 100,000
c. 156,000
d. this value is still quite uncertain.
8. How many stars does the Milky Way contain?
a. About 50 - 100 billion
b. About 100 - 400 billion
c. About 500 - 700 billion
d. More than a trillion
9. What is the closest galaxy to the Milky Way?
a. the Andromeda Galaxy
b. the Canis Major Dwarf
c. the Large Magellanic Cloud
d. the Small Magellanic Cloud
10. Our galaxy is one of the 54 members comprising a galactic cluster called "The Local Group." This Local Group, itself, is part of much larger agglomeration of galaxies known as ______________________.
a. The Virgo Super Cluster
b. The Scorpius Super Cluster
c. The Centaurus Super Cluster
d. The Local Super Group
ANSWERS
1. b. Milky Way
A bit of confusion. The "Milky Way" is the name of the diffuse light bridge traversing our sky. That "bridge"consists of light from the galactic plane. The name "Milky Way" also refers to our home galaxy.
2. a. barred spiral
The image below provides an "external view" of our home galaxy. This illustration shows us how astronomers believe our galaxy would appear if viewed from an outside perspective. Our Milky Way is a barred spiral galaxy, one with a bar in its center and from which radiates a series of enclosing spirals.
The Milky Way Our galaxy as we believe it appears when viewedfrom an external vantage point. We see a barred center and a series of
spiral arms. Image: NASA
3. b. the Orion-Cygnus Arm
Astronomers have confirmed that our galaxy consists of four well defined spiral arms. Our solar system is tucked away within the Orion-Cygnus Arm of the Milky Way Galaxy. Refer to the image above.
4. c. Sagittarius A
Abbreviated Sgr A*, this supermassive black hole is located about 26,000 light years from the solar system in the direction of the constellation Sagittarius the Archer.
5. a 4.5 million times more massive than the Sun
Astronomers can measure this mass by analyzing the motions of stars within the vicinity of this black hole. The more massive the black hole, the faster these stellar velocities.
6. c. 225 million years
In the amount of time required to read this sentence, the solar system will have traveled about 715 miles in its orbit around the galaxy. Right now, we're moving at nearly 145 miles per second through the Milky Way Galaxy. At that rate, we'll complete one orbit in about 225 million years.
7. b. 100,000
We live in a major barred spiral galaxy. It measures 100,000 light years from end to end. A light year is the distance light travels in one year through a vaccum: a distance equal to 5.8 trillion miles.
8. b. About 100 - 400 billion
Our Galaxy is home to hundreds of billions of stars. The exact number is unknowable, owing to the zone of avoidance that blocks our view of a sector of the galaxy on the other side of the nucleus. Yet, astronomers are quite sure that the Milky Way contains between 100 - 400 billion stars.
9. b. the Canis Major Dwarf
The Andromeda Galaxy is the closest spiral galaxy to the Milky Way, but it is not the closest galaxy. That honor goes to the Canis Major Dwarf Galaxy, which is 42,000 light years from the galactic nucleus and only 25,000 light years from our solar system. (So, technically, we're closer to the Canis Major Dwarf than we are to the galactic center.) The Canis Major Dwarf will eventually be torn apart by the Milky Way Galaxy and its stars will become incorporated into it.
10.a. The Virgo Super Cluster
Remarkably, this super cluster is just one of more than 10 million super clusters within the observable Universe. As we can see from the image below, our local group represents just a small part of this super cluster. The Virgo Super Cluster's diameter exceeds 110 million light years!
