Transcript introduction to astronomy phys 271

INTRODUCTION TO
ASTRONOMY
Overview
FRONTIERS IN ASTRONOMY
PHYS 271
North America
• Landsat Satellite Images
Earth from SPACE
• APOLLO 17 IMAGE
Earth and Moon
• From Galileo Spacecraft on way to Jupiter
Comparison of Earth and Moon
• Relative Diameters
• Earth ~ 8000 miles, Moon ~ 2160 miles
Distance to the Moon
• About 240,000 miles (similar to the
Diameter of Saturn’s Rings)
The Moon
• Mare Orientale: a large lunar crater on the
East Limb (edge). ~ 700 miles Diameter
The Sun
• Much larger than the Planets
The Sun
• The Chromosphere with a large
Prominence (~ 864,000 miles in Diameter)
The Corona in X-Rays
• Active regions (solar activity)
The Astronomical Unit
• Average distance between Sun and Earth
• ~ 150 million Kilometers or 93 million miles
Size of the Sun
• 109 times the diameter of Earth
Relative Size of the Planets
• Pluto smaller than the Moon
Orbits of the Planets
• Eccentricity and inclination of Pluto’s Orbit!
The Sky – Celestial Sphere
• North and South Celestial Poles
• The Celestial Equator
Rotation or Spin
• Rotation of the Earth - time scale Day
• 24 hours with respect to the Sun
Rotation of SKY – Star Trails
• 23 hours and 56 minutes, diurnal motion
Diurnal Motion Near Horizon
• Western or Eastern Horizon
Circumpolar Stars or constellations
• They never set, 23 hours 56 minute clock
Revolution
• The orbit of the Earth (sky changes)
Constellations
• Chance alignments in different directions
Summer Triangle
• Looking in different directions from Sun
Winter Constellations
• Use your imagination – anthropomorphic
Stars very far away
• Pleiades (A star cluster size of full Moon)
Milky Way – Our Galaxy
• Looking toward Andromeda Nebula
About 200 billion stars
• Some close, some intermediate, some far
Andromeda Galaxy
• Nearest Major Galaxy –
• 2.7 million Light Years distant
Clusters of Galaxies
• 100s or 1000s of individual galaxies!
Giant Elliptical Galaxy
Standard Candles
• Dominates Centers of most Clusters
• Among Brightness Objects we know
Clusters more and more remote
• Billions of light years distant
Hubble Deep Field
• Smallest blue objects more than 10 billion
light years distant