Transcript Astronomy & the Process of Science

Observations of the Sky
What
What
patterns, motions, and events do we
notice in the sky?
theories can we create to explain them?
How
Observations of the sky
can these theories be tested?
WHAT DO YOU THINK?
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Is the North Star—Polaris—the brightest star in
the night sky?
How many zodiac constellations are there?
What causes the seasons?
Does the Moon have a dark side that we never
see from Earth?
Is the Moon ever visible during the daytime?
What causes lunar and solar eclipses?
Observations of the sky
Constellations
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Groupings of stars in the same direction
Orion
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Pattern repeats every year
Observations of the sky
Leo
Constellations by familiar shapes &
by definition of regions
Observations of the sky
Constellations as guides !
Observations of the sky
Constellations in the Summer
Observations of the sky
Constellations in the Winter
Observations of the sky
Measuring the sky with angles…
Observations of the sky
Observations of the sky
Time-lapse photo looking North! WHY???
Observations of the sky
“Circumpolar” Constellations
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Some constellations always visible
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… and they rotate around Polaris
Observations of the sky
Finding your Latitude!
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The HEIGHT of Polaris indicates Latitude
Altitude angle
Observations of the sky
Stars don’t set!
How the sky moves at the north pole over time…
Observations of the sky
Stars set
straight DOWN
How the sky moves at the equator over time…
Observations of the sky
How the sky moves at a latitude like Hayward…
Observations of the sky
The Sun
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Rises in the East, sets in the West…
D Parkinson
… for *most* observers, but not all!
… not always due East, nor due West!
Observations of the sky
The Sun
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It takes about 24 hours to repeat
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How it rises & sets depends on position!
Near Equator, almost straight up/down
 Near Poles, very “shallow” angle!
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Observations of the sky
Seasonal Patterns
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Height of Sun varies over the year
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It gets hot in summer, and cold in winter!
Observations of the sky
Seasonal Patterns
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Summer:
 Sun
higher in the sky, shining more DIRECTLY
 Sun up longer, more hours in the day
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Winter:
 Sun
lower in the sky, less direct light
 Sun not up as long
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Does DISTANCE matter??
Observations of the sky
Seasonal Patterns
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Sun’s “speed” across the sky varies
Upper loop = Summer,
Earth moves slower in
its orbit
lower loop = Winter,
Earth moves faster
in its orbit
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The “analemma” is famous…
Observations of the sky
Seasonal Patterns
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Bergamo, Italy
Photos by John Nystuen, University of Michigan
Observations of the sky
Process of Science Example!
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Observations
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Seasons! (hot, cold patterns that repeat yearly)
Research
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Building Testable Theories & Hypotheses
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Sun’s distance causes seasons?
Do the experiment
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Happens every year
Sun is closer in northern winter!
Throw out the hypothesis! Revise the theory!
Observations of the sky
Process of Science Example!
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More Observations
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Earth “tilts” towards polaris
More Research
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Building Testable Theories & Hypotheses
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Earth tilts “closer” to the sun to create summer?
Do the experiment
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23. 5 degrees
Earth’s orbit is elliptical – still MUCH closer in Jan
Throw out hypothesis again!
Observations of the sky
Process of Science Example!
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STILL More observations!
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Sun’s height changing, length of day varies
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Southern Hemisphere seasons reversed
Research
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Building Testable Theories & Hypotheses
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Earth’s tilt creates seasons
Do the experiment
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Absorption of Solar Radiation
Seasons on other tilted planets? Yes!
Publish, continue the process….
Observations of the sky
The planets
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Five objects move relative to the Zodiac
Tunc Tezel, apod031216
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Each does it differently, at different times
but eventually, you can see a pattern.
Observations of the sky
The Moon
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A sequence of repeated phases over
about a “moonth”
Observations of the sky
The “wobble” of Earth…
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Precession changes direction Earth’s
rotation axis points in the sky
Observations of the sky