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Origin of the Universe. Raisin bread analogy of an expanding universe. Expansion Evidence.
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Expansion Evidence Stars are made of elemental gases that emit specific wavelengths within the electromagnetic spectrum based on their chemical composition. Each gas emits certain wavelengths that are unique to that element. The combination of a star’s elements which produce a pattern of spectral lines can be used to identify the star rather like a fingerprint or bar code.
Shifting of Wavelengths is called the Doppler Effect Change in the wavelength of light emitted by an object due to its motion Movement toward “squeezes” the wavelength Shorter wavelength Light shifted toward the blue end of the spectrum Movement away stretches the wavelength Longer wavelength Light shifted toward the red end of spectrum
RED SHIFT – BLUE SHIFT The greater the degree of shift of the spectral lines, the faster the object is moving away The star light DOES NOT appear red or blue (it still appears as white light from the star) The “bar code” for each element either shifts to the shorter wavelength blue end of the spectrum or to the longer wavelength red end of the spectrum
What is the best inference that can be made concerning the movements of Galaxies A, B, and C?
Nebular Theory 1. The sun and planets formed from a rotating disk of dust and gases. 2. As the speed of rotation increased the disk flattened out. 3. Matter became concentrated in the center where the sun eventually formed.
OUR SOLAR SYSTEMInner Planets Are referred to as terrestrial planets because they consist mostly of solid rock and are similar to the Earth.
OUR SOLAR SYSTEMOuter Planets • Are grouped together because they are large and gaseous. The are called “Jovian” planets because they are similar to Jupiter. • They are larger than the terrestrial planets, have a much lower density and are composed of mostly gases.
Terrestrial Planets – Earth largest solid, smaller, denser NO LONGER CONSIDERED A PLANET
Models of the Solar System a) Geocentric “Earth Centered” – Ptolemy believed the Earth was a sphere that stayed motionless at the center of the universe b) Heliocentric “Sun Centered” – Copernicus believed the Earth and other planets orbited the sun.
Rotation – spinning of the Earth on it’s axis (24 hours – day & night) Revolution – the Earth orbiting around the sun (365 days - seasons)
Precession • Is the slight wobbling of the Earth’s axis over 26,000 years.
A. Perihelion – Earth is closest to the sun (about 147 million km). This happens on Jan.3rd. B. Aphelion – Earth is farthest from the sun (about 152 million km). This occurs on July 4th.
Law #1: Law of Ellipses – The path of each planet around the sun is an ellipse with the sun at one focus.
1. What is the eccentricity of the ellipse below? d = 1 f1 f2 L = 10 2. Which planets have an orbit that is less eccentric than the ellipse above? 3. Which planets have an orbit that is more eccentric than the ellipse above?
Law #2 Law of Equal AreasAs a planet revolves around its focus points, it will cover the same area in equal time.http://www.phy.ntnu.edu.tw/java/Kepler/Kepler.html
Law #3: Law of Periods The farther a planet is from the sun, the longer it will take to complete one orbit (revolution) around the sun.
Solar Activity Sunspots- cool, dark areas of gas within the photosphere that are caused by powerful magnetic fields.
What color stars are hottest? Coldest? Red Super Giants Red Giants MAIN SEQUENCE COLOR AND TEMPERATURE ARE RELATED! White Dwarfs
Foucault’s Pendulum Foucault used a large free-swinging pendulum. Once put into motion a pendulum will continue swinging in the same direction unless acted upon by an outside force. Sharp points on the bottom of the pendulum made marks in a circular motion and returned to its starting position after 24 hours.
2. Foucault’s pendulum proved that the Earth DOES rotate on an axis.
