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Science 9 Questions: Chapter 10.2 Galaxies Review Questions With Answers
P356-363
1. What is a nebula?
A nebula is a cloud of gas and dust in space
2. What is the difference between a nebula and a galaxy?
A galaxy is an enormous collection of gas, dust and billions of stars held together by gravity.
3. List the three basic shapes of galaxies.
Spiral, Elliptical (like a football or cigar), Irregular
4. What characteristics do all galaxies share?
The have millions of stars, dust and gas – all held together by strong gravity forces
5. What do we call stars that are bunched together in part of a galaxy?
A star cluster
6. Even if humans had a spaceship that could travel at the speed of light, it is unlikely they would ever
travel across our galaxy. Explain.
It would take 100 000 years for a person to travel across just the stellar disk of the Milky Way galaxy,
travelling at the speed of light..
7. Not every star visible from Earth has a name. Why not?
It is much easier to number the stars than to name each one since there are million/billions to name.
8. Earth is located in one of the arms of the spiral galaxy, the Milky Way. How do you think the
appearance of the night sky would differ if our location were much closer to the centre of the
galaxy?
The night sky would be much brighter, perhaps even brighter than our daytime sky is now.
9. How does the speed at which a galaxy rotates affect its shape?
The faster the galaxy rotates, the flatter it becomes.
10. Besides shape, what other ways do galaxies differ from each other?
Galaxies differ in size, in mass, in colour, in brightness, in speed of spin, in the number of stars they
contain, in the type of stars they contain, and the kind of gas and dust they contain.
11. Does the statement “Galaxies would not exist if it were not for nebulas” make sense? Explain.
This makes sense because galaxies form from nebulas (clouds of gas and dust that gather together because
of gravity to form stars).
Science 9 Questions: Chapter 10.2 Galaxies Review Questions With Answers
P356-363
12. The image below shows the bright galaxy cluster Abell 2218 and the hundreds of other galaxies in
this region of space. Explain what a galaxy cluster is and what causes it to form.
A galaxy cluster is a group of galaxies that are held close together by gravity. It is thought that most of the
mass holding the galaxies together is “dark matter”, matter that does not radiate any form of light radiation.
Galaxy clusters are thought to have formed relatively recently (anywhere from 10 billion years ago to the
present time). Galaxy clusters form after galaxies form due to the large gravity force that one galaxy has
on close neighboring galaxies. Some galaxy clusters have clumped together (due to gravity) to form
superclusters, the largest objects known in our universe.