Aim: What is the Big Bang Theory? Dominant theory of universe formation Big explosion 13-18 billion years ago that was trillions of degrees in temperature.

What was there before the universe formed? Infinitely dense universe with an infinite temperature compressed into the confines of an atomic nucleus Known as singularity The moment before creation when space and time did not exist

Evidence of the Big Bang The appearance of distant galaxies moving away from us due to our knowledge of the doppler effect. The discovery of cosmic background radiation.

Point source moving to the right The Doppler Effect As a point source is moving, its frequency appears to change to a stationary observer Observed for both sound and light Point source at rest Point source moving to the right

Redshift - Sir William Huggins (1863) When an object moves away from us, its light waves are stretched into lower frequencies or longer wavelengths, and we say that the light is redshifted. Observed a red shift in the star Sirius

What does this tell us? This tells us that the star is moving away from us The Universe must be expanding Expanding Universe as if it were an expanding balloon

Cosmic Background Radiation Big Bang Theory predicts the existence of cosmic background radiation (the “glow” left over from the explosion itself)

The Earth and all the planets revolve around the SUN. Heliocentric Model The Earth and all the planets revolve around the SUN. The SUN is the center of the Universe (later we figured out it was just the center of the Solar System)

Evidence for Earth’s Rotation - The Foucault Pendulum - The Coriolis Effect - Star Trails

The Foucault Pendulum Foucault, is a simple device conceived as an experiment to demonstrate the rotation of the Earth At either the North Pole or South Pole, the plane of oscillation of a pendulum remains fixed relative to the distant masses of the universe while Earth rotates underneath it, taking one sidereal day to complete a rotation. So, relative to Earth, the plane of oscillation of a pendulum at the North Pole undergoes a full clockwise rotation during one day; a pendulum at the South Pole rotates counterclockwise.

Towards Sirius Pendulum is swinging in the same direction It’s the Earth that changed its orientation What we see is: 6 hours later

The Coriolis Effect

Arctic Circle 66.5º N: 666 km/h Columbus, Ohio 40º N: 1280 km/h The Earth rotates at different rates at different latitudes This is because different latitudes are different distances around Equator 1670 km/h

The result is that anything moving in a straight line over many degrees of latitude will be deflected

Star Trails

Polaris – The North Star The altitude of Polaris at your location is equal to your latitude on Earth. The altitude of Polaris NEVER changes, unless you change your LATITUDE. All other stars appear to rotate around Polaris.

= 41o YOUR LATITUDE ALTITUDE OF POLARIS We live at 41o N latitude, so the altitude of Polaris here is: 41o

The stars within this band are divided into 12 (or 13) constellations (groups of stars that form a pattern). These are the constellations of the zodiac.

So why are you the sign you are? On the day you were born, the sun was in front of your constellation.

Evidence for Earth’s revolution Different star constellations are seen from Earth different times of the year.