Formation of the Universe

Mr. Pratt – Earth Science

Early AstronomyGeocentric Model

• Aristotle• Ptolemy• Earth was an unchanging

constant with everything else going around us in circular paths. • Math supported…most of the

observations, but some things, like Mars, didn’t work.

Heliocentric Model

• Aristarcus• Nicolaus Copernicus• Earth was part of all the circular

motion and not at the center. • Sun is the center of the universe,

with Earth and everything else orbiting it. • Explained planetary motion of

Mars and the phases of Venus.

Answer the following:

• What is the retrograde motion of planets, specifically Mars?

• Why do we see Venus in different phases, similar to the moon? Why does Venus appear smaller when it’s “full”?

Stellar Observations: The Wanderers

• There are 7 wanderers in the sky, including the Sun, Moon, and a few planets. These all appear to move on the constant back ground of stars. Galileo’s telescope added planets and the moons of Jupiter!• For centuries, observers have found patterns in the night sky called

constellations. Twelve of these were found in the path of the Sun and are known as the Zodiac.• Explain or diagram the zodiac ring and how your zodiac sign is

determined. • When can you see your zodiac sign?

More Recent Astronomy (1880-1920)With a better understanding of wandering planets & moons, telescopes and electromagnetic technology allowed us to more closely analyze stars.

Edward Pickering: He began and oversaw the classification of thousands of stars and galaxies. Hired numerous female astronomers.

Annie Cannon: Developed a classification system for stars based on temperature and color.

Williamina Fleming: Adjusted the classification system to include luminosity.

Henrietta Leavitt: Using variable luminosity periods, she is credited with discovering how to calculate the distance from Earth to faraway galaxies.

The Life Cycle of Stars• Today, we use the Hertzsprung-

Russell diagram to classify stars. This has helped our understanding of how stars are born, what they do, and their eventual fate.• Diagram a simple life cycle of a low-

mass star and a high-mass star.

Edwin Hubble (1889-1953)• Discovered that spiral

galaxies exist outside the Milky Way.

• Used Henrietta Leavitt's math for measuring the distance of galaxies.

• Proposed an expanding universe model.

• Hubble's Law: Galaxies that are farther away are moving faster.

Make an analogy...• In class, we used a balloon to demonstrate Hubble's law. As the universe

expands, things are moving farther and farther apart from each other in multiple directions.• Think of a metaphor (not a balloon) that exhibits expansion. Draw this

example of expansion in your notebook with an explanation of how it relates to Hubble's law.• Redshift of light showed how galaxies that are farther away are moving

faster--greater redshift of light!

Cosmic Background Radiation

• Microwave radiation that is leftover from an early stage in the development of the universe--the oldest light!• Measured in detail in all

directions, cosmologists cannot attribute the radiation to any stars or galaxies.• Any model of the universe must

contain this background noise.

An accidental discovery

• Science requires people to share knowledge and cooperate. • Arno Penzias & Robert Wilson

worked for Bell Laboratories and were working with this radiometer in astronomy and for satellite communication.• They accidentally discovered the

background radiation and ended up receiving the Nobel Prize!