General Concepts The Universe began with an explosion, the big bang, over 13 billion years ago. Our galaxy, the Milky Way, contains billions of stars and the universe contains billions of galaxies. Stars differ from each other in size, temperature and age. Our Sun is a medium- sized star.

The Big Bang Theory: In the Beginning Big Bang Theory – all the matter and energy of the universe was contained in a very small area that exploded, sending material flying outward into the “empty space”

Cosmic background radiation – microwave radiation detected from space is an “echo” of the big bang. Red-shift in the light from distant galaxies – indicates that galaxies are moving away from each other. Evidence Supporting the Theory

Galaxies: Star Communities A galaxy is a group of billions of stars, dust and gas held together by gravity. Types : Barred SpiralSpiralElliptical

Milky Way – our galaxy (a barred spiral), composed of over 100 billion stars and is 100,000 light years across. (Wow, that’s far!) Our Neighborhood

Another View of the Milky Way galaxy Light-year = distance traveled by light in one year!

Complete the following: Place these terms in order from biggest to smallest: Solar System, Galaxy, Universe, Star Universe, Galaxy, Solar System, Star

Doppler Effect – the apparent shift in the wavelength of energy from objects as they move toward or away from the observer. − red shift – object is moving away from you the apparent shift toward the red end of the EM spectrum − blue shift – object is moving towards you the apparent shift toward the blue end of the EM spectrum Determining Star Motion BLUE end of the Spectrum RED end of the Spectrum

Doppler Effect - Visual

The farther a galaxy is away from Earth, the greater the red-shift. Therefore, galaxies far away are moving away faster!

Evidence from the Doppler Effect shows that galaxies are all moving away from one another! What does this mean for our Universe? It’s expanding!

Our Sun is a medium mass, main sequence star. Most of a star’s life is spent during this most stable stage of life.

B) Luminosity (Brightness) & Temperature of Stars (ESRT p.15) This is NOT a star map! The locations of stars on this graph are not related to their actual position in space.

Life Cycle of Stars PROTOSTAR HIGH MASS MAIN SEQUENCE STAR LOW TO MEDIUM MASS MAIN SEQUENCE STAR RED GIANT RED SUPERGIANT SUPERNOVA WHITE DWARF BLACK HOLE REMNANT NEUTRON STAR NEBULA

Electromagnetic Spectrum

Higher Frequency Lower Frequency

The “Old” Model Ptolemy Geocentric Model of the Solar System

The “New” Model Copernicus Heliocentric Model of the Solar System

Formation of Solar System (approximately 5 bya) Hot gases and dust Sun was born fusing Hydrogen into Helium Inner planets were not solid in the beginning Many show signs of violent formation impact craters volcanic evidence

Sun At the center of Solar System Massive Gravitational pull makes it the boss!

The Inner Planets (Terrestrial) 1)Mercury – very hot (day) and very cold (night) 2)Venus – poisonous atmosphere 3)Earth – life, active crust 4)Mars – evidence of surface water in the past Characteristics: Small & rocky (terrestrial) Few, if any, moons Relatively close together Long period of rotation Short period of revolution

The Outer Planets (Jovian) 5)Jupiter 6)Saturn 7)Uranus 8)Neptune Characteristics:giantgaseous many moons rings relatively far apart

The Balance of Gravity and Inertia Gravity Inertia

Keppler’s 1 st Law Planets orbit the sun in orbits that are elliptical (not perfect circles), regular, cyclical, and predictable motions. The sun is at one “focus” of the orbit. Guided Notes

Keppler’s 2 nd Law The line joining a planet and the Sun “sweeps out” equal areas in an equal amount of time. Guided Notes

Keppler’s 2 nd Law (eccentricity of orbit is exaggerated) Close to Sun Fast Speed Strong Gravity High KE & Low PE Far from Sun Slow Speed Weaker Gravity Low KE & High PE

Keppler’s 2 nd Law Planets will move at different rates during their orbit and they will “sweep-out” an equal area of space over equal time 30 days

Kepler’s 3 rd Law The orbital speed of a planet is related to its distance from the Sun.

Measuring the Eccentricity of an Ellipse ** Eccentricity values range from 0 – 1, with 0 being a circle and 1 being a straight line distance between foci d length of major axis L =Eccentricity =

Average Distance between the Earth and the Sun is about million km