Contributions To
Science
Tycho Brahe
&
Johannes Kepler
Tycho Brahe
And his contributions to science…
A little about Tycho
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Born on December 14,
1546 in what is now
Sweden.
He attended the
universities of
Copenhagen, Leipzig,
Wittenberg, Rostock, and
Basel.
During this time his
interest in astronomy really
started to grow.
Tycho’s Nose
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A part of the bridge
of his nose was cut
off in a duel at
University of
Rostock in 1566.
He had a metal
piece attached to
where the part was
missing as a
replacement.
Observations
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Brahe observed the
new star Cassiopeia
in 1572
He proved that
comets are not
objects in the
atmosphere.
Made a extremely
accurate star
catalogue containing
1000 stars.
Spent most of his life
working on his
astronomical tables
(before the telescope
Some of the tools he used…
Tycho’s World System

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Tycho believed that the Earth
was in the center of the world.
The sun and the moon
circulated around it. The rest
of the planets circulated
around the sun.
This is based mostly on
measurements from mars.
The
Sun
Earth
Johannes Kepler
And his contributions to science…
A little about Johannes
Johannes was born
December 27, 1571 in
Germany
 Went to University Of
Tübingen
 Tycho Brahe’s
assistant.
 Used Tycho’s tables to
prove the laws of
planetary motion

Kepler’s 1st Law of Planetary Motion
(Elliptical orbits)
 The
orbits of
the planets
are ellipses,
with the Sun
at one focus
of the
ellipse.
Elliptical Orbits

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All ellipses have 2 foci
A planet’s distance from
the sun will change
throughout its orbit
beacause the sun is at
one focus of the ellipse.
Aphelion- point farthest
from the sun
Perihelion- point
nearest to the sun
Watch these orbits a

At first you can not tell
that a planets orbit is not
a circle.

Pluto and Mercury are
exceptions
Kepler’s 2nd Law of Planetary Motion
(Equal Area Law)

The line joining the planet to the Sun
sweeps out equal areas in equal times
as the planet travels around the
ellipse.
nd
2
Law (continued)
 This
means that the speed at
which a planet travels around
the sun is not constant.
 Planets travel more rapidly
when they are closer to the sun
(could not explain why)
Kepler’s 3rd Law (harmonic law)

The ratio of the squares of the
revolutionary periods for two planets
is equal to the ratio of the cubes of
their semimajor axes
To practice
Kepler’s 3rd
law click here
rd
3
Law (continued)
The time it takes a planet to travel one
orbit around the sun is its period.
 This law states that the Period of a
planet squared equals the cube of its
distance: P2=D3
 Period must be in Earth years and
distance from the sun in astronomical
units
 So the farther a planet is away from the
sun, the longer its period of revolution
is.

Interactive
Websites
Johannes
Kepler
Orbits
Kepler's
Tyhco
Third Law
Brahe
 Tycho Brahe
Bibliography
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Works Cited
Abbott, David, ed. "Tycho Brahe & Johannes Kepler." The
Biographical Dictionary of Scientists. Astronomers ed. 4 vols.
New York: Peter Bedrick Books, 1984.
"Johannes Kepler: the Laws of Planetary Motion." 16 May
2006
<http://csep10.phys.utk.edu/astr161/lect/history/kepler.html>.
Koch, David, and Alan Gould, comps. "Johannes Kepler: His
Life, His Laws and Times." NASA. 28 July 2005. 15 May
2006 <http://kepler.nasa.gov/johannes/>.
Spaulding, Nancy E., and Samuel N. Namowitz. Earth
Science. Ed. Ceanne Tzimopoulos. Evanston, Illinois:
McDougal Littell, 1994. 405-406.
"Tycho Brahe, Danish Astromer 14/12 1546 - 24/10 1601."
Tycho Brahe Homepage. 9 Sept. 2002. 12 May 2006
<http://www.nada.kth.se/~fred/tycho/index.html>.
"Tycho Brahe." The Galileo Project. 1995. 10 May 2006
<http://galileo.rice.edu/sci/brahe.html>.