WarmUp he xpanding Universe

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Warm-Up The Expanding Universe

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Words to Know

Write the letter of the definition next to the matching word as you work through the lesson. You may use the glossary to help you.

dark energy A. a change in wavelength of a wave due to the source and observer moving closer or farther apart

B. a type of energy that opposes gravity and causes the expansion of the universe

C. a small planet-like object that can combine with others to form planets

D. the portion of a nebula that remains after the formation of a protostar

E. a massive explosion from which the universe originated about 13.7 billion years ago

F. a type of matter that fills space and is undetectable at the moment

planetesimal

Doppler effect

dark matter

solar nebula

big bang

Lesson Goals

Lesson Question

WK2

Learn about theories relating to the formation of theuniverse.

Describe the big bangtheory.

Describe whatastronomers predict forthe future of the universe.

Explain how the

formed.

system


Warm-Up The Expanding Universe

Parts of the Universe

Space and all things in space make up the universe.

• The universe is made of .

• Galaxies contain single stars, star systems and clusters, gas, dust, and solar systems.

• Solar systems include a and all the objects that orbit around

it, such as planets, moons, asteroids, and comets.

Composition of the Universe

The universe consists of and .

• Matter is anything that takes up and has weight.

• Energy is the ability to do work.


The Expanding Universe

Origin of the Universe: The Big Bang Theory

The universe began about 13.7 billion years ago with an called the big bang.

• At its start, the universe was no bigger than the size of a pinhead before it exploded.

• The universe continued to expand rapidly and gradually cooled.

• like hydrogen and helium formed.

• Stars and formed.

The Doppler Effect

Scientists use the Doppler effect to learn about the behavior of the .

• Red shift: Light from a galaxy moving away from Earth will seem

stretched into longer , toward the end of the spectrum.

• shift: Light from a galaxy moving toward Earth will seem

compressed into shorter wavelengths, toward the blue end of the spectrum.

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Edwin Hubble (1889–1953)

• Was an American astronomer who pioneered the exploration of space

• Fought in the army in World War I and World War II

• Was invited to join the team at Mount Wilson Observatory in California

• Discovered existed outside the Milky Way

Hubble’s Law

Hubble measured the velocities of galaxies using the effect.

• Determined almost all galaxies are moving away from us

• Discovered Hubble’s law, which states that the farther away a galaxy is,

the it is moving away

• Concluded the universe started from a point.

His findings supported the big bang theory.

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The Hubble Space Telescope

The Hubble Space Telescope was launched into Earth’s orbit in 1990, resulting in new discoveries.

Cosmic Background Radiation

The presence of background radiation in the universe supports the big .

• In 1965, two physicists detected faint radiation while

building a receiver.

• This radiation is uniform and detected in every

.

• Scientists believe it is

leftover

energy from the big bang.

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The Hubble Space Telescope The Nebula



Formation of the Solar System

The solar system formed in a similar fashion to stars: in a nebula.

• A solar collapsed about 5 billion years ago to form our

solar system.

• pulled the solar nebula together.

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The solar nebula spun faster and faster as it .

• It flattened into a rotating disk, with most of the gas pulled toward the

.

• This gas became hot and dense and the Sun was born.

• About 98% of the matter of the solar system is in the .

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Dating the Universe

Astronomers use several factors to calculate the of the universe, including:

• the of background radiation.

• how fast distant galaxies are moving away from us.

• the age of the oldest stars.

Astronomers believe the universe is approximately 13.7 billion years old.


The Expanding UniverseInstruction

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Planetesimals

Smaller bodies formed in the solar system when and combined.

• Gas and dust continued to combine and grow to form planetesimals.

• Planetesimals are believed to form in debris disks.

• Planetesimals collide, stick together, grow larger, and eventually form

.

Inner Planets

The inner planets are also called the planets and include Mercury, Venus, Earth, and Mars.

• They formed when the of the solar system was

very high, near the Sun.

• These planets are smaller than those in the outer system.

• Gases escaped from these planets’ gravity as they formed.


The Expanding UniverseInstruction

Outer Planets

The Outer planets are also called the gas and include Jupiter, Saturn,

Uranus, and .

• They formed farther away from the Sun, where temperatures were cooler.

• They grew larger, increasing their gravity.

• This allowed them to capture hydrogen and helium, creating thick

.

• Farther out, a huge disk of ice and other debris formed, creating Pluto, comets, and other bodies.

Gravitational Condensation and Accretion

Gravitational condensation and accretion are two processes involved in the formation

of .

• Gravitational condensation is the formation of solid particles from

solar materials.

• Accretion is an in the size of an object as a result of the

addition of materials.

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Accretion of Planetesimals

Gravitational condensation can lead to the accretion of planetesimals.

• A dust grain grows as atoms and molecules are added to it.

• Masses of form

around the grain.

• Masses and form

planetesimals.

• Large planetesimals clump together and form .

Accretion of Protoplanets

Gravitational can lead

to the accretion of protoplanets.

• A protoplanet pulls materials from its surroundings.

• The more materials

near the protoplanet, the bigger its core.

• The bigger its core, the

the pull of gravity.

• The more the materials condense, the the protoplanet grows.



Dark Energy in the Universe

Visible matter only makes up about 5% of the universe.

“Empty” space is not truly empty.

It contains:

• dark .

• dark .

The Universe

Dark energy

Dark matter

Other

Dark EnergyIn 1998, scientists discovered that the expansion of the universe has been

.

• Scientists do not know why this acceleration is occurring.

• They call the force causing this phenomenon dark energy.

Possible Future of the Universe

Astronomers have theorized several important possible outcomes for the future.

• It is possible that the universe may continue to .

• Stars could burn out, causing the universe to become and cold.

• Gravity could pull galaxies back together, causing a reverse of the big bang.

Based on observations that expansion of the universe is accelerating, astronomers believe the most likely outcome is that the universe will continue to expand.

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Vera Rubin (1928–2016)

• Was an American astronomer and winner of the National Medal of

• Faced significant throughout her career

• Proved that galaxies spun faster than they should based on their visible matter

• Determined there must be invisible matter influencing their

• Was later credited with helping prove the existence of dark matter

Dark Matter

Dark matter is different from “normal” matter.

• It is .

• It does not emit radiation like stars, planets, and nebulae.

• Scientists can only observe the effects of its .

Scientists know very little about dark matter or dark energy.


The Expanding UniverseSummary

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Review: Key Concepts

• The universe formed from a massive explosion called the big bang about 13.7 billion years ago.

• The solar system formed from the collapse of a solar .

• The Sun formed at the center of the nebula from the majority of the gas and dust.

• Inner planets formed close to the Sun, where were high, and gas was burned away.

• Outer planets formed at a distance away from the star, where temperatures were cooler, so gas did not burn away.

• Astronomers believe that the universe will continue to based on observations.

• It is made up mostly of dark energy and dark matter.

Answer

Lesson Question How do scientists theorize that the universe formed??


The Expanding UniverseSummary

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WarmUp he xpanding Universe