S282: Book2 - Chapter 1 & 2

Well - another weighty tomb awaits us in the shape of Book 2, An Introduction to Galaxies and
Cosmology (435p). The first book was all about the birth, life loves and death of stars. In this book we take a step back and look at the bigger picture of how galaxies are born, live and die.
If you thought finding out details of stars which are all tiny pin pricks of light was hard, well its much simpler than galaxies. Galaxies are orders of magnitude further away than stars so the amount of light you can capture is typically smaller.

Anyway - we start the book with Chapter 1 looking at the Milky Way - our own galaxy. This allows us to explore what it is made up of (and stars are are pretty minor component!), its shape such as the halo (including the dark matter one) and the bulge, some of the oddities within it such as open cluster and globular clusters.

Then Chapter 2 looks at regular galaxies. There are a lot of different galaxies out there and naturally the first thing the early people did was to lump them together into categories. So we have spirals (with and without bars), ellipticals, lenticular and irregulars. These are classified according to the Hubble scheme (or other variants).
Then there is quite a section on how we work out the distance to these galaxies - which is pretty hard work. Many techniques are not very accurate but give a good appreciation of the order of magnitude.

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