Lecture 2 The Solar System The Universal Gravitation - PowerPoint PPT Presentation

Lecture 2 the solar system the universal gravitation l.jpg
1 / 27

  • Uploaded on
  • Presentation posted in: General

Lecture 2 The Solar System The Universal Gravitation. Chapter 1.3  1.11. Homework: On-line quiz for Chapter 1 (due August 27th). Outline. What we see in the sky The Ptolemaic system The Copernican system, Kepler’s laws Universal gravitation. Patterns of stars seen in the sky

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Lecture 2 The Solar System The Universal Gravitation

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Lecture 2 the solar system the universal gravitation l.jpg

Lecture 2The Solar SystemThe Universal Gravitation

Chapter 1.3  1.11

Homework: On-line quiz for Chapter 1 (due August 27th)


  • What we see in the sky

  • The Ptolemaic system

  • The Copernican system, Kepler’s laws

  • Universal gravitation

Constellations l.jpg

Patterns of stars seen in the sky

There are 88 constellations

About 50 of them were named by ancient Greeks and Romans


Constellation of orion l.jpg

Constellation of Orion

Winter triangle l.jpg

Winter triangle

Daily star paths l.jpg

Daily star paths

Seasonal changes in the sky l.jpg

Seasonal changes in the sky

Annual change of the sun altitude l.jpg

Annual change of the Sun altitude

Ancient observations l.jpg

Relations of celestial objects to weather and agriculture

Observations of the Sun and Moon

Observations of stars and planets

Ancient Observations

Ptolemaic model of the universe l.jpg

Ptolemaic model of the Universe

Developed by Claudius Ptolemy (A.D. 100-170)

The Earth is in the center

The Sun is at the third orbit from Earth after Mercury and Venus

Epicycles are added to circular orbits of planets to explain retrograde motion

Ptolemy a d 100 170 l.jpg

Ptolemy (A.D. 100  170)

Ptolemaic epicycles l.jpg

Ptolemaic Epicycles

The Ptolemaic model along with a catalog of positions of 1028 stars were published in his book Almagest

Nicolaus copernicus 1473 1543 l.jpg

Nicolaus Copernicus (14731543)

Copernicus is said to be the founder of modern astronomy

Kepler s laws l.jpg

Kepler’s Laws

  • Planets move on elliptical orbits

  • 2. The planet’s radius-vector sweeps out the same areas in equal times

  • 3. The squares of the periods of the planets are proportional to the cubes of their semi-major axes

Demonstration of Kepler's laws

The solar system l.jpg


Sun (the only star)

9 planets

Nearly 100 moons



Free-flying gas and ``dusty’’ particles


The Solar System

Planets of the solar system l.jpg

Planets of the Solar System

Sir isaac newton 1642 1727 l.jpg

Sir Isaac Newton (1642-1727)

The universal law of gravitation l.jpg

The Universal Law of Gravitation

Every mass attracts every other mass through the force called gravity

The force of attraction is directly proportional to the product of their masses

The force of attraction is inversely proportional to the distance between the objects

Fg = G x M1x M2 / d2


The universal law of gravitation18 l.jpg

The Universal Law of Gravitation

Support of kepler s laws l.jpg

Support of Kepler’s Laws

Newton found that Kepler’s first two laws apply not only to planets, but to any object going around another one under the force of gravity

The orbits do not have to be elliptical

They can also be parabolic or hyperbolic

Tides l.jpg


Tides are due to gravitational attraction between the Earth and the Moon

Spring tides l.jpg

Spring Tides

Neap tides l.jpg

Neap Tides

Tidal friction and synchronous rotation l.jpg

Tidal Friction and Synchronous Rotation

The tidal bulges try to stay on the Earth – Moon line

The Earth’s rotation tries to pull the bulges around

The tidal friction slows down the Earth’s rotation

The length of a day gets longer

It makes the Moon move further away from Earth

The Moon is in synchronous rotation with the Earth

(always showing the same face)

The discovery of neptune l.jpg

The Discovery of Neptune

In 1781, the planet Uranus was discovered telescopically

from Britain by William Herschel.

In 1845, a Cambridge mathematician, John Couch Adams, based on the law of gravitation, predicted the existence of an unseen planet, to account for the fact that Uranus was being pulled slightly out of position in its orbit.

He sent the calculations to test to England’s Royal Astronomer, who set them aside.

Shortly after that, a French mathematician, Urbain Leverrier,published a similar prediction and contacted astronomers at Berlin Observatory, who found the new planet on the night of 23 September 1846.

Urbain leverrier 1811 1877 l.jpg

Urbain Leverrier (18111877)

Astronomy and astrology l.jpg

Astronomy and Astrology

Astronomy is a science

It describes the real world, sets new problems and solves them, using methods of itself and other sciences (such as physics and mathematics)

Astrology is interpreting apparent positions of the Sun, planets, and stars to predict human life.

It does not set and solve any problem

Summary l.jpg

The Earth is not the center of the universe but instead is a planet orbiting a rather ordinary star in the Milky Way Galaxy.


  • Celestial bodies in the gravitational field of each other move according to Kepler’s laws.

  • Newton’s discoveries showed that the same physical laws we observe on Earth apply throughout the Universe.

  • Login