Planetary Motion
&
Historical People in Astronomy

Earth Science
Overview of our Solar System


Earth is one of the 8 planets revolving around,
or orbiting, the sun.


All the planets, as well as most of their moon
(satellites), orbit the Sun in the same direction,
and all their orbits,...


Humans have been watching the skies for
1000s of years, and early ideas were
developed solely on the basis of Earth-bas...


We have gathered much information through
the use on modern technology. Spacecraft,
telescopes (ground based & space ba...
Influential People in Astronomy
1. Ptolemy (85 –
165 AD) –
proposed that
objects ORBIT
around an
unmoving Earth
(GEOCENTRI...
Ptolemy
2. Tycho Brahe (1546 – 1601)


The astronomical
Made important
instruments of
contributions by
Tycho Brahe
devising the most
precise instruments
avail...
Initially Tycho designed
a zodiacal armillary
sphere, which could be
used to obtain the
ecliptic co-ordinates of
celestial...
Using Trigonometry
Brahe cont…


His observations of planetary motion,
particularly that of Mars, provided crucial
data for later astronomer...
Brahe cont…




Brahe proposed a model of the solar
system that was intermediate between the
Ptolemaic and Copernican mo...
3. Copernicus (1473 – 1543)
Copernicus…





1st to propose that planets ORBIT around
the Sun (Heliocentrism).
CONTROVERSIAL at the time!!!
4. Galileo (1564 – 1642)
Galileo…



Adhered to Copernicus
theories and as a result
he was brought forward in
1633, and, there, in front
of his “b...
5. Kepler (1571 – 1630)




Developed the 3 laws
on planetary motion.
Described how planets
moved around the sun.
1st Law (Eccentricity):


The orbit of each planet is the shape of an
ellipse (oval –shaped) with the sun located at
one ...
Ellipses can have different shapes, usually characterized by their "eccentricity." A circle
is a special case of an ellips...
Aphelion


When planet is at its farthest point from
the sun. 93 million miles!!!
Perihelion


When a planet is at its closest point from
the sun. 91 million miles!!!
2nd Law (Law of Equal Areas):






In any time interval, a line from a planet to the
sun will sweep out equal areas.
N...
Planet will “sweep”
slower here.

Time: AB = CD
Planet will “sweep”
faster here.
Gravity gets stronger as the planets come...
Universal Gravitational Law:

6.67300 × 10-11 m3 kg-1 s-2
Universal Gravitational Law


Example: There are 2 objects in space. One is
50 kg and another is 65 kg. They are 12 m
apa...
3rd Law (Law of Harmonies)







The ratio of the squares of the
periods of any two planets is
equal to the ratio of t...
Using the 3rd Law (write out):

a)
b)

We can use the 3rd law to find:
Distance from sun.
Orbital period of a planet.
Example:






Jupiter’s average distance from the sun is
5.20 AU. What is its orbital period?
If a = 5.20, then a3 = ...
Let’s try… Determine the orbital period:
Planet
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto

Distance fro...
6. Newton (1643 – 1727)
Newton’s view on planetary
motion…
 Newton

proposed that the
planet’s motion is due to 2
forces: Inertia and gravity.
Wh...
2. Sun’s gravity pulls
Earth.

Combined, it causes the planets to orbit around the sun.

1. Earth’s
tendency of
movement i...
Rotation


The time it takes for a planet spin or
rotate on its axis once.

Examples:
a) Earth = 24 hours
b) Mercury = 59...
Revolution




a)
b)

The time it takes for a planet to go
around the sun once.
Examples:
Earth = 1 year
Pluto (dwarf pl...
Planetary Motion & Historical People in Astronomy
Planetary Motion & Historical People in Astronomy
Planetary Motion & Historical People in Astronomy
Upcoming SlideShare
Loading in …5
×

Planetary Motion & Historical People in Astronomy

939 views

Published on

Published in: Education, Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
939
On SlideShare
0
From Embeds
0
Number of Embeds
6
Actions
Shares
0
Downloads
21
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Planetary Motion & Historical People in Astronomy

  1. 1. Planetary Motion & Historical People in Astronomy Earth Science
  2. 2. Overview of our Solar System  Earth is one of the 8 planets revolving around, or orbiting, the sun.
  3. 3.  All the planets, as well as most of their moon (satellites), orbit the Sun in the same direction, and all their orbits, lie near the same plane.
  4. 4.  Humans have been watching the skies for 1000s of years, and early ideas were developed solely on the basis of Earth-based observations.
  5. 5.  We have gathered much information through the use on modern technology. Spacecraft, telescopes (ground based & space based).
  6. 6. Influential People in Astronomy 1. Ptolemy (85 – 165 AD) – proposed that objects ORBIT around an unmoving Earth (GEOCENTRISM ).
  7. 7. Ptolemy
  8. 8. 2. Tycho Brahe (1546 – 1601)
  9. 9.  The astronomical Made important instruments of contributions by Tycho Brahe devising the most precise instruments available before the invention of the telescope for observing the heavens. Tycho Brahe
  10. 10. Initially Tycho designed a zodiacal armillary sphere, which could be used to obtain the ecliptic co-ordinates of celestial bodies (celestial longitude and latitude) directly, without any calculation.
  11. 11. Using Trigonometry
  12. 12. Brahe cont…  His observations of planetary motion, particularly that of Mars, provided crucial data for later astronomers like Kepler to construct our present model of the solar system.
  13. 13. Brahe cont…   Brahe proposed a model of the solar system that was intermediate between the Ptolemaic and Copernican models (it had the Earth at the center). It proved to be incorrect, but it was the most widely accepted model of the Solar System for the time.
  14. 14. 3. Copernicus (1473 – 1543)
  15. 15. Copernicus…   1st to propose that planets ORBIT around the Sun (Heliocentrism). CONTROVERSIAL at the time!!!
  16. 16. 4. Galileo (1564 – 1642)
  17. 17. Galileo…  Adhered to Copernicus theories and as a result he was brought forward in 1633, and, there, in front of his “betters,” he was, under the threat of torture and death, forced to his knees to renounce all belief in Copernican theories, and was thereafter sentenced to imprisonment for the remainder of his days.
  18. 18. 5. Kepler (1571 – 1630)   Developed the 3 laws on planetary motion. Described how planets moved around the sun.
  19. 19. 1st Law (Eccentricity):  The orbit of each planet is the shape of an ellipse (oval –shaped) with the sun located at one focus. (There are 2 foci in an ellipse).
  20. 20. Ellipses can have different shapes, usually characterized by their "eccentricity." A circle is a special case of an ellipse. It has zero eccentricity.
  21. 21. Aphelion  When planet is at its farthest point from the sun. 93 million miles!!!
  22. 22. Perihelion  When a planet is at its closest point from the sun. 91 million miles!!!
  23. 23. 2nd Law (Law of Equal Areas):    In any time interval, a line from a planet to the sun will sweep out equal areas. NOTE: As the planet goes around the sun, the further away it is, the slower it ORBITS. This is due to the gravitational attraction between the Sun and Earth. A planet sweeps out at equal amounts of area in equal amounts of time.
  24. 24. Planet will “sweep” slower here. Time: AB = CD Planet will “sweep” faster here. Gravity gets stronger as the planets come “near” the sun.
  25. 25. Universal Gravitational Law: 6.67300 × 10-11 m3 kg-1 s-2
  26. 26. Universal Gravitational Law  Example: There are 2 objects in space. One is 50 kg and another is 65 kg. They are 12 m apart. What is the gravitational force between them? F= F= 6.67300 × 10-11 [(50 kg)(65 kg)] 12 m 1.505 x 10-9 N Basically, a) the bigger the object, the stronger the gravity and b) the closer the object, the stronger the gravity.
  27. 27. 3rd Law (Law of Harmonies)    The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. P2 = a3 P = time2 it takes to go around the sun. 3
  28. 28. Using the 3rd Law (write out):  a) b) We can use the 3rd law to find: Distance from sun. Orbital period of a planet.
  29. 29. Example:     Jupiter’s average distance from the sun is 5.20 AU. What is its orbital period? If a = 5.20, then a3 = 140.6. Use formula: P2 = a3 The orbital period must be the square root of 140.6, which equals about 11.8.
  30. 30. Let’s try… Determine the orbital period: Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Distance from Sun (AU) 0.387 0.723 1 1.524 5.203 9.539 19.191 30.071 39.457 Orbital Period P2 = a3 0.241 0.616 1 1.88 11.9 29.5 84.0 165.0 248.0
  31. 31. 6. Newton (1643 – 1727)
  32. 32. Newton’s view on planetary motion…  Newton proposed that the planet’s motion is due to 2 forces: Inertia and gravity. When combined, the planets move in an elliptical orbit.
  33. 33. 2. Sun’s gravity pulls Earth. Combined, it causes the planets to orbit around the sun. 1. Earth’s tendency of movement is in a straight line (Inertia).
  34. 34. Rotation  The time it takes for a planet spin or rotate on its axis once. Examples: a) Earth = 24 hours b) Mercury = 59 days
  35. 35. Revolution   a) b) The time it takes for a planet to go around the sun once. Examples: Earth = 1 year Pluto (dwarf planet) = 248 years

×