Theme 3 Part 2 – Revolutionary Times: Copernicus and Tycho Brahe ASTR 101 Prof. Dave Hanes.
Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus:...
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Transcript of Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus:...
![Page 1: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/1.jpg)
Kepler’s Laws
1. Definitions: Law, Theory, etc.
2. Johannes Kepler
3. Patterns of Orbits
4. Bonus: Tycho Brahe
![Page 2: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/2.jpg)
Fact
• Data, measurements.– “This winter Boston got 108.6 inches of
snow.”
• Sometimes, obvious conclusions from data.– “Boston’s winter of 2014-2015 was the
snowiest winter on record.”
![Page 3: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/3.jpg)
Law
• A simple relationship or formula that is found through observations or experiment, and describes what happens, and may or may not address why it happens.
• Laws can later be explained (and turn into a theory), or can remain unexplained and thus just be coincidences (sometimes called an empirical law).
![Page 4: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/4.jpg)
Bode’s Law
Well, it’s also possible we just don’t
understand planet formation well enough yet…
![Page 5: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/5.jpg)
Theory
• A hypothesis (reason why) that has been tested many times and is accepted by the scientific community.
![Page 6: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/6.jpg)
Example Theories
• Gravity
• Big Bang
• Nuclear fusion and fission
• Germs cause disease
• Dinosaurs were killed by an asteroid
• Evolution
• Global warming / climate change
![Page 7: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/7.jpg)
Kepler’s Laws don’t say WHY things happen, they only
describe WHAT happens.
![Page 8: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/8.jpg)
Johannes Kepler
Germany1571-1630
http://en.wikipedia.org/wiki/Image:Johannes_Kepler_1610.jpg
![Page 9: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/9.jpg)
Kepler = Heliocentric
Tycho Brahe’s student, used his data to support heliocentric
![Page 10: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/10.jpg)
Kepler’s Laws
1. Ellipses
2. Equal Areas
3. P2=a3
![Page 11: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/11.jpg)
1. Planets orbit the Sun in ellipses, with the Sun at
one focus
![Page 12: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/12.jpg)
http://www.astro.virginia.edu/class/oconnell/astr121/im/ellipse-geom-NS.gif
![Page 13: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/13.jpg)
http://hyperphysics.phy-astr.gsu.edu/hbase/imgmec/kep5.gif
![Page 14: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/14.jpg)
Kepler’s Laws
1. Ellipses
2. Equal Areas
3. P2=a3
![Page 15: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/15.jpg)
2. Planets’ orbits sweep out equal areas in equal times.
![Page 16: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/16.jpg)
http://physics.uwyo.edu/~stark/outreach/Kepler/oldareaellipse.gif
![Page 17: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/17.jpg)
http://upload.wikimedia.org/wikipedia/commons/7/75/Kepler2.gif
![Page 18: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/18.jpg)
2. Planets’ orbits sweep out equal areas in equal times.
When one planet is closer to the Sun, it moves faster than when the same planet is farther from
the Sun.
![Page 19: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/19.jpg)
Kepler’s Laws
1. Ellipses
2. Equal Areas
3. P2=a3
![Page 20: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/20.jpg)
3. P2=a3
• Period - in Earth years
• Semi-major axis (average distance from the Sun) - in AU
• One planet close to the Sun orbits in a shorter time than a different planet farther from the Sun.
![Page 21: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/21.jpg)
Kepler’s Law of Periods Multiple Versions
1. P2=a3 – around the Sun, years and AUs
2. P2=ka3 – any units, but k is different for each unit set and for each central object
3. (Below) – true for all units, all central objects
2 3
A A
B B
P a
P a
![Page 22: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/22.jpg)
Newton’s Laws (including gravity) explain all of Kepler’s Laws.
![Page 23: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/23.jpg)
Newton’s Theories explain Kepler’s Laws
1. Ellipses • Gravity (F=GMm/r2) makes objects move
in this sort of shape.
2. Equal Areas• Conservation of Angular Momentum,
which follows from Newton’s Laws.
3. P2=a3
• Gravity (F=GMm/r2) causes this too.
![Page 24: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/24.jpg)
Kepler’s Laws
1. Ellipses
2. Equal Areas
3. P2=a3
![Page 25: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/25.jpg)
Tycho BraheGermany
1546-1601
http://en.wikipedia.org/wiki/Image:Tycho_Brahe.JPG
![Page 26: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/26.jpg)
Tycho Brahe = Geocentric
Best measurements of planets
![Page 27: Kepler’s Laws 1.Definitions: Law, Theory, etc. 2.Johannes Kepler 3.Patterns of Orbits 4.Bonus: Tycho Brahe.](https://reader036.fdocuments.us/reader036/viewer/2022081515/56649f355503460f94c53c5c/html5/thumbnails/27.jpg)
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