1. When galaxies interact, the individual stars do not typically ever hit one an
ID: 284940 • Letter: 1
Question
1. When galaxies interact, the individual stars do not typically ever hit one another. Think of one or two analogies from everyday life, where two collections of objects can merge or pass through one another to occupy the same space, but the individual objects in the groups do not hit one another. The wider the spacing between the objects relative to their size, the better the analogy will be at helping you visualize galaxy mergers.
2. Describe how the temperature of the Universe has been changing with time, and how we know what it is now.
3. Explain what a "theory" means in science, and why it is a trustworthy explanation.
Explanation / Answer
1)
As two galaxies move toward one another, they begin to get stretched out because eachgalaxies gravity is acting on the other galaxy, when they hit, no physical collisions occur, butshapes are distorted by the other galaxies gravityExpansion acts between distance galaxies and clusters, but not within a cluster – within acluster and over short distances gravity acts on galaxies – have to be very close for galaxy todefy expansion and act on the gravityAll galaxies have supermassive black hole at the center – some galaxies, like ours, it iscompletely dark, but in active galaxies it is brightEvidence for SMBHs –Large Mass – we can see objects orbiting based on alternating redshift/blueshift – bymeasuring speed of orbiting object we can figure out the mass inside of the orbitCompact/Small Size – we see rapid changes in brightness of these objects over time,which shows they have a small physical sizeEnergy Source/High Luminosity – nothing else we know of other than accretiondisks that produce that much light
2)
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