GenS 4001 Astronomy

Tutorial Questions 5:
Galaxies

These questions are for discussion during the tutorial on the above topic.

Are all the stars we can see members of our Milky Way galaxy?
Where in the Milky Way is our Solar System located?
Do all galaxies have spiral arms? Are most of the stars within a galaxy found within the spiral arms?
Which types of galaxies are the ones most likely to be forming stars? How can we tell?
Some galaxies in our own 'Local Group' have only just been discovered, despite that fact that we can see some galaxies billions of light years away. How could they have remained hidden from us for so long? Are astronomers not particularly observant?
What is a 'supermassive black hole'? How might such a beast power 'active galaxies' and 'quasars'?
Are galaxies isolated objects?
Are all galaxies moving away from our Milky Way?
What do you understand by the expression "The Universe"? Does it contain everything that we might possibly be able to see, assumming we had a sufficiently powerful telescope?

The results of the MAP satellite, mapping the cosmic microwave background radiation, now tell us that visible matter (stuff like us, planets and stars) only makes up 4% of the mass of the Universe. 23% of the mass is unseen 'dark matter', something we can feel but can't see. 73% is an even more mysterious 'dark energy' which, not only can we not see it, is causing the expansion of the Universe to accelerate. It now appears that the first stars formed when the Universe was just 180 million years old. The Universe is now 13.7 billions years old, and will continue to expand forever. Do you find these results amazing?! Is there anything else left to discover about the Universe?