Origin of the UniverseOrigin of the Universe

Raisin bread analogy of an Raisin bread analogy of an expanding universeexpanding universe

Expansion Evidence Expansion Evidence

Stars are made of elemental gases that emit Stars are made of elemental gases that emit specific wavelengths within the electromagnetic specific wavelengths within the electromagnetic spectrum based on their chemical composition. spectrum based on their chemical composition. Each gas emits certain wavelengths that are Each gas emits certain wavelengths that are unique to that element. unique to that element.

The combination of a star’s elements which The combination of a star’s elements which produce a pattern of spectral lines can be used produce a pattern of spectral lines can be used to identify the star rather like a fingerprint or bar to identify the star rather like a fingerprint or bar code. code.

Electromagnetic Spectrum

Shifting of Wavelengths is called Shifting of Wavelengths is called the Doppler Effectthe Doppler Effect

• Change in the wavelength of Change in the wavelength of light emitted by an object due light emitted by an object due to its motion to its motion

• Movement toward “squeezes” the Movement toward “squeezes” the wavelengthwavelength

• Shorter wavelengthShorter wavelength

• Light shifted toward the blue end Light shifted toward the blue end of the spectrum of the spectrum

• Movement away stretches the Movement away stretches the wavelength wavelength

• Longer wavelengthLonger wavelength

• Light shifted toward the red end Light shifted toward the red end of spectrumof spectrum

RED SHIFT – RED SHIFT – BLUE SHIFTBLUE SHIFT

• The greater the degree of shift of the spectral The greater the degree of shift of the spectral lines, the faster the object is moving awaylines, the faster the object is moving away

• The star light DOES NOT appear red or blue (it The star light DOES NOT appear red or blue (it still appears as white light from the star) still appears as white light from the star)

• The “bar code” for each element either shifts to The “bar code” for each element either shifts to the shorter wavelength blue end of the spectrum the shorter wavelength blue end of the spectrum or to the longer wavelength red end of the or to the longer wavelength red end of the spectrumspectrum

What is the best inference that can be made concerning the movements of Galaxies A, B, and C?

Our solar system is part of the Our solar system is part of the spiral Milky Way Galaxyspiral Milky Way Galaxy

Edge-on view of the Edge-on view of the Milk Way GalaxyMilk Way Galaxy

Spiral galaxy in the constellation Spiral galaxy in the constellation AndromedaAndromeda

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.

• 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.

OUR SOLAR SYSTEMOuter Planets

Terrestrial PlanetsTerrestrial Planets – Earth largest – Earth largest solid, smaller, densersolid, smaller, denser

NO LONGER CONSIDERED A PLANET

Earth compared to Earth compared to Jovian PlanetsJovian Planetsgaseous, large, low densitygaseous, large, low density

Models of the Solar System

1. 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?

f1 f2

d = 1

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.

MAIN SEQUENCE

Red Super Giants

Red Giants

White Dwarfs

COLOR AND TEMPERATURE ARE RELATED!

What What color color stars are stars are hottest? hottest? Coldest?Coldest?

Which groups of stars are the BRIGHTEST?

Which group of stars is the HOTTEST?

Which groups of stars are the SMALLEST and DIMMEST?

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.

Horizon and Zenith

Path of the Sun

Path of

the Sun

Moon Phases

Half of the moon is always receiving light from the sun.

The “lit” portion that is visible to earth varies as the moon REVOLVES around earth. THIS CAUSES THE PHASES OF THE MOON.

Visible portion of moon growing = waxingVisible portion of moon shrinking = waningThe moon phases are cyclical – they are re-

occuring or repeating in the same pattern.

Phases of the Moon

Lunar Phases

Cycle of Lunar Phases

Takes 29.53 daysThis is because when moon gets back to

its original position in 27.3 days, the earth has moved 1°/day or about 27°.

The moon moving at l3°/day takes about 2 days to catch up with Earth and align with it and the sun in a new moon phase.

What we observe from earth

How much of the moon we see

depends on where the moon is in its

orbit:

Appearance:

Appearance:

Appearance:

Lunar Eclipse

Lunar Eclipses

Solar Eclipse

Solar Eclipses

TidesAre caused by the Moon and Sun’s gravitational pull on the water of the Earth.

When the sun & moon form a right angle (90) with the Earth water is pulled in all directions. This causes a Neap tide. Water level is very constant.

The sun, moon, & Earth are in a straight line this is a Spring Tide. There will be a very high High Tide and a very low Low Tide.