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Astronomy 1021 Study Guide - Comprehensive Final Exam Guide - Sun, Gravity, Earth


Department
Astronomy
Course Code
ASTR 1021
Professor
Robert Cockcroft
Study Guide
Final

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Astronomy 1021

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Sunday, October 2, 2016
Mastering Astronomy Quiz #1 Notes
Astronomy
-As the Earth orbits the Sun, the moon orbits around the Earth, completing one loop
roughly every four weeks
-What fraction of the moon is always lit by the Sun? At any point in its orbit, half of the
moon is illuminated by the sun (just as half of the earth is always illuminated by the
sun).
-The same side of the moon always faces the earth. The illuminated portion of the
moon however, does not always face the earth. Why is this?
-Because the Moon makes exactly one rotation around its own axis during each
of its orbital revolutions around the earth.
-The orbital position of the Moon determines both the lunar phase and the time of day
th which the moon rises and sets.
-Full moon always rises at dusk
-First quarter Moon will rise at noon
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Tuesday, January 10, 2017
WEEK #1 SEMESTER 2
ASTRONOMY
-Energy produced by fusion heats the gas and builds up enough pressure to balance
gravity.
-So the sun is fighting gravity
It is not winning, it is losing
The stalemate is only temporary
-As sun was born from collapsing cloud of interstellar has the contraction of all gas
caused gravitational potential energy to be turned into kinetic energy which heated
the sun up.
-The strong force: acts like superglue, binding neutrons and protons together. At short
distances, there is a force that pulls protons together.
-At the center of this collapsing cloud, the density increased, the pressure increased
and the temp increases.
The buildup of pressure is the first attempt to stop gravity.
-Sun was born with enough hydro to shine steadily for a lifetime of 10 billion years/
Halfway through life cycle presently.
When all you have is helium, the pressure of gravity collapses star and it dies.
-On earth we need some upward pressure to counteract gravity.
-If there isn’t a balance of pressure and gravity, things change.
-Sun couldn’t survive just as a core. Shelves above it (layers) that provide outwards
pressure.
-If temp of suns core increases just a lil, fusion rates would increase a lot. That would
increase temp further. Thus increasing pressure. This would cause the core to
expand, If it expands, it’ll cool down. And return fusion rate to normal.
-The sun is getting brighter because the core contracts slight due to total number of
particles slowly decreasing over a long time. Fusion rate increases and energy
production goes down.
!1
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