CELESTIAL MOTION Outcome #3 – Sun & Solar System
Feb 24, 2016
CELESTIAL MOTION
Outcome #3 – Sun & Solar System
ASTRONOMY• ASTRONOMY is the study of what is
beyond earth (usually called “space”).
• The UNIVERSE is everything that exists including all matter and energy. We often call the universe “space”.
UNIVERSE
• What is included in “space”:1. GALAXIES – a huge collection of gas and
dust and millions of stars and planets.2. SOLAR SYSTEMS – a sun and all of the
objects that travel around it.3. STARS – a large collection of matter
which emits a huge amount of energy through nuclear fusion. Stars also form patterns called CONSTELLATIONS.
4. PLANETS – a large piece of matter that revolves around a star.
5. MOONS – a piece of matter that revolves around a planet.
6. SATELLITES – an object that travels in orbit around another object.
7. COMETS – a chunk of ice/dust that travels in a long orbit around the sun.
8. ASTEROIDS – a small rocky object in space.
9. METEORS – a streak of light caused by a meteoroid.
10.METEOROID – a lump of rock/metal trapped by earth’s gravity.
11.METERORITE – a meteoroid that has reached the ground.
MILKY WAY GALAXY
OUR SOLAR SYSTEM
MOTION• Everything in the universe is moving
(stars, planets, meteors, asteriods, moons, etc...)
• In fact the universe is getting larger even as we sit here!
PLANETARY MOTION• Planets are constantly in motion.
They move in 2 basic ways:– ROTATION– REVOLUTION
• ROTATION: The spinning of an object around its axis. It is because of Earths rotation we have day & night.
• The Earth rotates once on its axis every 24 hours.
ROTATION
REVOLUTION: The movement of one object travelling around another. Earth travels in a counter clockwise direction, relative to the north pole, once a year (every 365.25 days) around the sun.
REVOLUTION
The Seasons are caused by the combination of the Earths tilted axis (23.45°) and the revolution motion of the Earth.
Winter in Northern Hemisphere
Fall in Southern Hemisphere
GEO-CENTRIC THEORY• In ancient times people believed that the Earth
did not move. They saw things moving in the sky and assumed they were moving around the earth.
• PTOLEMY was a Greek astronomer who first wrote about the “EARTH CENTERED UNIVERSE”, also called a GEO-CENTRIC universe.
• He also believed that the stars were only slightly farther away from Earth than the moon, sun, and other planets.
GEO-CENTRIC UNIVERSE
RETROGRADE MOTION• If you observe and record the position
of planets over a number of weeks, you will see that the planet creates an “S” shape in the sky. This is called RETROGRADE MOTION.
• Ptolemy believed that each planet revolved around a point on its orbit called the EPICYCLE.
VIDEOS1. http://
www.youtube.com/watch?v=on3LCB4C52w
2. http://csep10.phys.utk.edu/astr161/lect/retrograde/aristotle.html
HELIO-CENTRIC UNIVERSE
• In 1500 AD, COPERNICUS suggests a solar system with the Sun at the center.
• It was not until the 1600’s, when GALILEO used the first telescopes, that people began to accept that the sun was the center of our universe.
HELIO-CENTRIC UNIVERSE
VIDEOS1. http://www.youtube.com/watch?
v=GmwAr54L_pM&list=PLD7ED780492E5486A