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Origins of the Universe and Solar System From Universe to Galaxy to Solar System Two Observations about the Universe Led to the Big Bang Theory In 1965, scientists Penzias And Wilson discovered background radiation interfering with radio antennae, causing a hiss in phone lines. II. Evidence for Big Bang/Inflation • That radiation is called cosmic background radiation and is thought to be radiation from the big bang. • This radiation can be detected by common radio and television antennae. (ex: “snow” on an old television is made up of a small percent of radiation from the formation of the universe!) II. Evidence for Big Bang/Inflation 2. Astronomers observe “red shifts” of starlight throughout the universe. • This redness is the result of light waves being stretched as objects in the universe move away from each other (the result of the big bang). What is Doppler Effect? Doppler Effect is the change in frequency of a wave (such as a sound wave) when it is observed relative to a moving source (like a car) Light waves can also experience Doppler Effect when the source of the light (such as a star) is moving Astronomers observed that light from distant stars has been shifted towards the red end of the light spectrum. This phenomenon is called red shift. The farther away a star is, the more its light is shifted towards the red end of the spectrum, demonstrating that the universe is expanding…. I. Formation of the Universe The Big Bang Theory - The theory that the universe began as a point(singularity) and has been expanding ever since. • The universe was originally packed into one dense sphere of hydrogen about the size of a pearl! I. Formation of the Universe The Big Bang Theory - The theory that the universe began as a point(singularity) and has been expanding ever since. • The sphere “exploded”, forming a hot expanding cloud • As the cloud moved, parts condensed and formed billions of galaxies I. Formation of the Universe The Big Bang Theory -. • The galaxies continue to move outward today • Most commonly accepted theory of universe formation Theories on the Formation of the Universe Continued. B. The Steady State Theory - The belief that the universe doesn’t change with time but more matter is added to the universe as it expands. • Popular during the 1950s and 1960s • The universe had no beginning and has no end (no big bang) C. Inflationary Theory - predicts that there was a sudden expansion when the universe was very young, more extreme than predicted by the big bang theory! • Considered to be a “revised” Big Bang theory • The universe expanded and cooled until about 10-35 second after the big bang when it became so cool that the forces of nature caused the universe to inflate tremendously. • The initial expansion was faster than the speed of light. I. Formation of the Universe III. Formation of Galaxies 1. Galaxies began as a clouds of gas and dust (also called a nebulae) 2. The clouds collapsed under the force of their own gravity, forming galaxies of a variety of shapes. III. Formation of Galaxies 3. Our galaxy the Milky Way is a barred spiral galaxy, consisting of a nucleus surrounded by arms that rotate in a clockwise direction. Our solar system is here 4. Solar systems similar to ours move around in this galaxy in a regular pattern. IV. Shape of Galaxies 1. Sa Barred-Spiral (like the Milky Way--OUR galaxy). See background picture. 2. Spiral … some are SBb Barred Spirals 3. Irregular and others 2. Elliptical