chapter 1: why learn astronomy?. we have studied astronomy since ancient times astronomy is the...
TRANSCRIPT
Chapter 1:Why Learn Astronomy?
We Have Studied Astronomy Since Ancient
Times
Astronomy is the oldest science. Every ancient culture studied motions in the sky
Compared to the universe, the Earth is less than a grain
of sand on a beach
Watch YouTube Size Comparison and Journey to the Big Bang WMAP videos
Our Cosmic Address
We believe that superclusters are the largest structures to have formed thus far in the universe. Will something larger form in the far future? Probably not but we can’t say for sure.
Light travels at a finite speed: about 300,000
kilometers/second
Watch One Small Step HD video
Because of the finite speed of light, we can see back in
time
WMAP image of the Cosmic Background Radiation. Light from the edge of the visible
universe.
Play with Look Back Simulator in ClassAction Introductory Concepts
module
Astronomers use the
Scientific Method to
gain an understanding
of the Universe
Astronomers study the “patterns among the stars”
In order to make sense of what we see we need a Cosmological Principal
Mathematics is the language of Astronomy and Physics
Pythagoras569 – 475BC“The underlyingStructure of theUniverse isMathematical”
Isaac Newton 1642 – 1727 Newton invented
calculus to explain his mechanical
universe. The orbits of the planets were like the hands
on a giant clock
Albert Einstein 1879 – 1955According to
Einstein, the Universe is a much stranger place than Newton thought. Newton could never have imagined black holes but Einstein’s theories predict them.
Dealing with numbers large and small
Scientific Notation
4,500,000,000,000,000 = 4.5x1015
0.000000000000000028 = 2.8x10-17
Common Prefixescenti = 0.01 = 10-2 (c)milli = 0.001 = 10-3 (m)nano = 0.000000001 = 10-9 (n)kilo = 1,000 = 103 (k)mega = 1,000,000 = 106 (M)giga = 1,000,000,000 = 109 (G)
Range of numbers we deal with in astronomy
DistancesAround the Earth…meters (m) or kilometer (km) 1 m ≈ 39.37 inches 1 km = 1000 m = 0.621 miles
Around the Solar System…AU 1 AU = Average Earth – Sun distance 1 AU = 1.496x1011 m = 149.6 million km
Beyond the Solar SystemLightyear (ly)
1 ly = distance light travels in 1 year 1 ly = 9.46x1015 m = 9.46 trillion km
Parsec (pc): distance at which an object shows a
parallax of 1 arcsecond: 1pc = 3.26 ly= 30.84 trillion
km
Other UnitsMass…kilograms (kg)
1 kg = 1000 grams1 kg = 2.205 lbs*
*(a pound is not really a mass, it is a force. In the US, we tend to use it like a mass, though)
Time…Years, Days, Hours, Minutesand Seconds
Temperature…°C°C = (°F - 32°) x 5/9
also use Kelvin scale°K = °C + 273°