THE UNIVERSE AND ITS STARS

THE UNIVERSE AND ITS STARS13.1 The Origin of the Universe

Before we start!!

This section is not meant to question anyone’s beliefs. It is to inform you of the facts and theories currently present based on scientific observation. Theories often change through continuous research.

Hubble Telescope

• Confirmed existence of other galaxies • Galaxies are moving away from us• The further a galaxy is, the faster it is moving away from us

• These observations established the idea of an “expanding universe”

(Telescope named after Edwin Hubble)

Evidence for an Expanding Universe

• Hubble looked at light energy (travels like a wave)• Visible spectrum = ROYGBIV

• Wavelength of Red is longest and violet is shortest (see next slide)

• This spectrum shifts if a galaxy is standing still or in motion


Notice how energy increases towards violet which also results in a shorter wavelength.

Red = less energy = shorter wavelengthViolet = more energy = longer wavelength


• Imagine a boat floating. Any movement of the ship will cause ripples.

• These ripples are like wavelengths. Crest from one ripple to crest of next one is one wavelength.


• If the boat starts moving, the ripples at front of the boat will become closer together. Behind the boat, they’re further apart. In water, you could tell if an object is moving towards or away from you.

• Wavelengths of an object would do the same thing as the ripples on the boat. The wavelength of an object moving away from you will be longer than if it’s moving towards you (shorter)


• Spectroscope used to determine that galaxies are in motion• Every item has its own pattern in a spectroscope. Every

galaxy also has its own pattern. • For example, scientists looked at the Hydrogen spectrum

pattern. Found this pattern to be moved more towards the red-end of the spectrum, meaning, that wavelengths were longer and the galaxy was moving away from us. This is known as red shift

• The greater the red shift, the faster a galaxy is moving away




• Scientists thought that if everything is moving away, there must be a point in space and time where all this started. Just like an explosion.

• Determined this: • explosion started 13.7 billion years ago• Location is yet unknown

• This is known as the Big Bang Theory (explanation of what we observe in the universe, including the origin of the universe itself)

• Try This p 416

• The light reaching us from any source near or far does so at the same time.

• What do you think? Is this true or false?

Modern Support for Big Bang Theory

• Light from the Sun takes 8 minutes to reach Earth• This means that any light we see is 8 minutes old. • The farther away a light source is, the longer it takes to reach

us.• Imagine how old light from stars is! • If a galaxy is 13.2 billion light years away , how old is the light?

• 1965 detected radiation coming from every direction in space. Many scientists believe this radiation is what remains of the Big Bang and is the outer boundary of the universe

• It has a temperature of -273°C and is 13.7 years old

COBE & WMAP Providing Evidence for the Big Bang

• COBE = Cosmic Background Explorer• Found slight differences in temperature

of cosmic background radiation• Meant that matter matter spreading out

from the Big Bang was not evenly distributed

• WMAP = Wilkinson Microwave Anisotropy Probe• Confirmed age of universe is 13.7 billion years old ± 200 million years• Helped scientists determine when first stars formed

& gave clues about the first trillionth of a second of the universe

COBE & WMAP Providing Evidence for the Big Bang

COBE & WMAP support evidence for big bang theory, but there are still gaps.

New discoveries bring new knowledge which means these theories may change

Scientific method can test theories, explore them, and support or disprove them with new evidence from discoveries.

CYU p 418 # 4, 8, 10, 11, 13, 16

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THE UNIVERSE AND ITS STARS