Earth and Life Science Week 1

What contains all galaxies and solar systems?

Universe

What is made up of millions to trillions of stars?

Galaxy

What revolves around a single star?

Solar System

What theory explains the universe originated from an explosion of a dense core?

Big Bang Theory

What theory explains a rapid expansion faster than light occurred just after the Big Bang?

Cosmic Inflation Theory

Which theory believes the universe has no beginning or end and remains constant?

Steady State Theory

What term refers to continuous creation of matter as galaxies move apart?

Infinite Universe Theory

Who proposed the Nebular Hypothesis?

Immanuel Kant and Pierre-Simon Laplace

What caused the nebula to collapse in the Nebular Hypothesis?

Gravitational pull

What shape did the collapsing nebula take?

A pancake with a bulge at the center

Which theory says planets formed from matter torn off the Sun by a passing star?

Tidal Theory

Who proposed the Tidal Theory?

Sir James Hopwood Jeans and Harold Jeffreys

Which hypothesis involves a collision creating tides that formed planetesimals?

Planetesimal Hypothesis

Who proposed the Planetesimal Hypothesis?

Chamberlin and Moulton

What are planetesimals?

Small solid bodies that collided and formed planets

Why is the Big Bang Theory widely accepted?

It explains the expansion and formation of galaxies from a primordial explosion

Does the universe expanding mean Earth is moving away from the Sun?

No, Earth’s distance from the Sun is relatively stable due to gravity

What is the study of the universe called?

Cosmology

What distinguishes the universe from a galaxy and a solar system?

The universe contains roughly two trillion galaxies and their countless solar systems; a galaxy is made of millions to trillions of stars; a solar system is organized around a single star.

Roughly how many stars can a single galaxy contain?

Millions to trillions of stars.

According to the Big Bang Theory, where were all matter and energy found before the universe began?

Compressed in a primordial core that later exploded.

After the Big Bang explosion, what two components initially filled the early universe?

Intense radiation and particles.

What name is given to the rapidly expanding region that formed immediately after the Big Bang?

The primordial fireball.

How did galaxies originate under the Big Bang model?

Huge clumps of matter that broke apart from the primordial fireball became galaxies.

What does the Cosmic Inflation Theory add to the Big Bang scenario?

It states that the universe expanded far faster than the speed of light immediately after the Big Bang, then slowed to a steadier expansion.

State the core idea of the Steady State Theory.

The universe is expanding yet has no beginning or end, with ongoing creation of matter keeping its overall density constant.

What alternative names are used for the Steady State Theory?

Infinite Universe Theory or Continuous Creation.

In the Steady State model, how do new galaxies arise?

As existing galaxies move apart, new matter appears between them and condenses into new galaxies while old ones die.

Who proposed the Nebular Hypothesis of solar-system formation?

Immanuel Kant and Pierre-Simon Laplace.

According to the Nebular Hypothesis, what begins solar-system formation?

A giant rotating cloud of gas and dust (nebula) collapses under its own gravity.

In the Nebular Hypothesis, what does the central bulge of the flattened disk become?

The Sun.

Who developed the Tidal Theory of solar-system origin?

Sir James Hopwood Jeans and Harold Jeffreys.

Summarize the Tidal Theory in one sentence.

A massive star passing near the Sun pulled off material that later condensed to form the planets.

Who formulated the Planetesimal Hypothesis?

Thomas Chowder Chamberlin and Forest Ray Moulton.

What event produces planetesimals in the Planetesimal Hypothesis?

A close stellar encounter raises huge tides on the Sun, ejecting matter into elliptical orbits that cool into solid bodies called planetesimals.

How do full-sized planets grow in the Planetesimal Hypothesis?

Larger bodies in similar orbits absorb smaller planetesimals through repeated collisions.

What question about Earth’s future is posed at the end of the notes?

If the universe is expanding, is Earth moving farther from the Sun, and would that affect the sustainability of life on Earth?