Chapter 1 Our place In The Universe Student information Sheets Semester: ______________________ Astronomy 105 Section ___________ Dr. Robert Friedfeld How To Access on-line Materials http://www.physics.sfasu.edu/ http://www.astronomyplace.com/ What is this lecture section? 001 002 003
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Our place In The Universe
Astronomy 105 Section ___________
Dr. Robert Friedfeld
~ 40 Galaxies
More than 100 billion stars
The Local Supercluster
How did we come to be?
From the observed rate of expansion, Astronomers estimate that the expansion began sometime between (12-16) billion years ago.
Galaxies form a few billion years after the Big Bang
A Region of Space Expands with time
Earth was made of elements produced in stars long ago.
When we study the universe, it is impossible to separate space and time.
The Great Spiral Galaxy in Andromeda
The Earth rotates on its axis once each day.
As the Earth rotates, your speed around the Earth’s axis depends on your latitude.
The average distance of the earth from the Sun is called an astronomical unit or AU.
1AU = 150 million km = 93 million miles.
The plane of the Earth’s orbit around the Sun is called the ecliptic plane.
Axial Tilt of 23.5o
and has its shortest period of daylight of any day of the year.
An expanding raisin cake illustrates basic principles of the expansion of the universe