ASTR 103 Study Guide - Spring 2018, Comprehensive Midterm Notes - Orbit, Earth, Sun
12 Oct 2018
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Department
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ASTR 103
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Chapter 1 - Discovering the Night Sky
• Scientific Method - a reiterative process based on observations, logic, and skepticism
o Hypothesis - a concept or idea that seems to explain a phenomenon or set of
observations
o Model - a set of hypotheses that have withstood observational or experimental tests
o Theory - a set of related hypotheses can be pieced together into a self-consistent
description of natural observations
o Laws of Physics - theories that accurately describe the workings of physical reality,
and have stood the test of time and been shown to have great and general validity
Order of the Planets
• Mercury
• Venus
• Earth
• Mars
• Jupiter
• Saturn
• Uranus
• Neptune
• Pluto
Star is different than a Quasar - stands for Qazi Stellar
Angle Measurements in Astronomy
• The basic unit of angular measure to describe the apparent size of a celestial object - what
fraction of the sky that object seems to cover
• The angular diameter (or angular size) of the moon is 1/2 a degree, or the moon
subtends an angle of 1/2 a degree
• If you draw lines from you eye to each of two starts, the angle between these lines is the
angular distance between these two stars
• The adult human hand provides angle measurements
o The width of the finger (at the tip) - 1 degree
o The width of the hand (at its widest point) - 10 degrees
• One degree subdivides into 60 arcminutes
o Minutes of arc
o Abbreviated as 60 arcmin or 60'
• Subdivide one arcminute into 60 arcseconds
o Seconds of arc
o Abbreviated as 60 arcsec or 60"
• 1 degree = 60 arcmin (60')
• 1 arcmin (1') = 60 arcsec (60")
Prefixes for powers of Ten
find more resources at oneclass.com
find more resources at oneclass.com
• Billion (109)- Giga (G)
• Million (106) - Mega (M)
• Thousand (103) - kilo (k)
• Hundredth (10-2) - centi ( c )
• Thousandth (10-3) - milli - (m)
• Millionth (10-6) - micro
• Billionth (10-9) - nano
Astronomical Distances
• Astronomical Unit (AU)
o One AU is the average distance between Earth and the Sun
o 1.496*108 km or 92.96 million miles
• Light Year (ly)
o One ly is the distance light can travel in one year at a speed of about 3*105 km/s or
186,000 miles/s
o 9.46*10 km or 63,240 AU
• Parsec (pc)
o The distance at which 1 AU subtends an angle or 1 arcsec or the distance from which
Earth would appear to be one arcsecond from the sun
o 1 pc = 3.09*1013 km = 3.26 ly
• Naked eye (unaided - eye) astronomy had an important place in ancient civilizations
o Positional astronomy
• The study of the positions of objects in the sky and how these positions change
o Naked-eye astronomy
• The sort that requires no equipment but human vision
• Extends far back in time across all cultures
▪ British Isles Stonehenge
▪ Native American medicine wheel
▪ Aztec, Mayan, and Incan temples
▪ Egyptian pyramids
• Eighty-eight constellations in the sky - officially
o Ancient peoples looked at the stars and made groupings
• Pictures in the sky
• Different cultures different pictures
o We still refer to many of those groupings
o Astronomers call them constellations (From the Latin for "group of stars")
• Parts are asterisms
• Big dipper is an asterism of the Big Bear
• Modern Constellations
o On modern star charts, the entire sky is divided into 88 regions
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Order of the planets: mercury, venus, earth, mars. Star is different than a quasar - stands for qazi stellar. Astronomical distances: astronomical unit (au, one au is the average distance between earth and the sun, 1. 496*108 km or 92. 96 million miles. Light year (ly: one ly is the distance light can travel in one year at a speed of about 3*105 km/s or. 186,000 miles/s: 9. 46*10 km or 63,240 au, parsec (pc, the distance at which 1 au subtends an angle or 1 arcsec or the distance from which. Discovering the night sky: the moon, phases, and eclipses. We always see the same side of the moon! The moon rotates at the same rate that is revolves around the earth, so we see the same side of the moon all the time. The sun and the full moon have the about same angular size on the sky of . 5 degrees because -
