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Midterm

# AS101 Study Guide - Midterm Guide: Orbital Period, Lunar Eclipse, Deferent And Epicycle

10 pages75 viewsWinter 2013

Department
Astronomy
Course Code
AS101
Professor
Patrick Mc Graw
Study Guide
Midterm

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Lecture 11 2/11/2013 12:24:00 PM
MIDTERM REVIEW:
Time limit: 1 hour
50 questions, MC
covers chapter 1-3, but a little bit less on chapter 1, more on chapter 1.
Bring a calculator, but only a couple of questions require actual calculations.
Formulas and exact numbers you need will be givenyou just need to know
how to use them.
Some questions ask you to remember some of the basics, others ask you to
apply what you know in some of the ways we’ve practiced.
Chapter 1 Highlights:
An overview of our current understanding of the universe.
You should be able to:
o Describe what structures are bigger than what other
structures (example, solar system is part of the milky way
galaxy, galaxies are part of clusters, etc.)
o Describe the approximate relative sized of things (example: is
Jupiter a million times bigger across than earth, or is it more
like 10 times?)
Units:
o Know what the following mean: astronomical units, light year.
o Understand how to write a number in scientific notation.
Know how to convert units: for example, if 1 au = 1.5x10^8 km,
then how many km is 5 au?
Know very approximately the sized of things, enough to be able to
pick them out on a multiple choice list
Chapter 1 summary:
We live on a planet, orbiting a star, forming part of a solar system,
inside a galaxy, which is part of a cluster and supercluster.
Superclusters form even bigger structures like walls, filaments,
voids, etc.
Scientific notation:
o Make it easier to write and compare very large or very small
numbers.

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o Based on powers of 10
o So 3,000,000 = 3 x 10^6
o The exponent tells you how many places the first digit is from
the decimal point.
Astronomical unit (au)
o Defines as the average distance between the earth and the
sun,
o Mostly used for distances inside the solar system
Light year:
o The distance light travels in a year.
o Mostly used for distances between stars or bigger objects like
galaxies.
o If something is for example 4000 light years away, that
means we see it as it was 4000 years ago.
Large planet (Jupiter) is about 10 times as big across as earth.
Sun is about 10 times as big across as Jupiter, so that makes it
about 100 times as big across as earth.
Nearest other star: 4.3 ly away.
billion star.
Nearest other galaxies: 1-2 million ly away
Farthest visible objects:
Around 12 billion ly away. The visible part of the universe includes
around 100 bullion galaxies.
In our solar system, earth is a smallish planet, but not the smallest.
The un is a medium sized starsome are smaller but some are
bigger.
The milky way is fairly large compared to most, but not the largest.
And it is part of bigger structures: clusters, superclusters, etc.
Chapter 2 Highlights:
Locating things in the sky:
o Constellations and asterisms
o Angular distances.
o The celestial sphere.
The main cycles of the sky:

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o Daily: rising and setting, circles around celestial pole.
o Yearly: seasons, suns apparent motion around the ecliptic,
solstices, equinoxes, etc.
o Monthly: moon phases
o Eclipses.
Naming of stars
Declination and right ascension (for describing positions on the
celestial sphere)
Changing your point of view (how does the sky look from different
places on the earth?)
Angular sixe (depends on both actual size and distance away from
the observer)
Precession.
Chapter 2 Summary:
Constellations:
o 88 regions in the sky, with well defined boundaries. Every
star is in one constellation. Examples: ursal major, orion,
Taurus…
Asterisms:
o Patters or visible groups of stars.
o Example: the big dipper, the winter circle.
o They may include starts from more that one constellations.
Note: stars with the same constellation or asterism appear close to
each other, but they might actually be at very different distances.
Zenith:
Horizon:
o Is 90˚ away from the zenith.
Meridian:
o A north-south line passing through the zenith.
Celestial north (south) pole:
o The point on the celestial sphere directly above the north
(south) pole of the earth.
Celestial equator: