ASTR 103 Study Guide - Comprehensive Final Exam Guide - Orbit, Earth, Sun
95 views114 pages
20 Nov 2018
School
Department
Course
Professor
ASTR 103
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