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Questions and Answers
What is cosmology?
What is cosmology?
The branch of astronomy that deals with the origin, large-scale properties, and the evolution of the observable universe.
What is meant by 'the universe' in astronomy?
What is meant by 'the universe' in astronomy?
The sum total of all things which can be directly observed or whose physical effects on other things can be detected.
What is the Big Bang Theory?
What is the Big Bang Theory?
It is the theory that the universe was created from a cosmic explosion that occurred between 10 billion and 20 billion years ago.
What did Edwin Hubble determine about galaxies?
What did Edwin Hubble determine about galaxies?
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What significant discovery did Arno Penzias and Robert Wilson make in 1965?
What significant discovery did Arno Penzias and Robert Wilson make in 1965?
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The steady state theory posits that the universe is always expanding while maintaining a constant average density.
The steady state theory posits that the universe is always expanding while maintaining a constant average density.
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The __________ states that if there is sufficient matter in the universe, gravity will eventually cause a reverse of the Big Bang.
The __________ states that if there is sufficient matter in the universe, gravity will eventually cause a reverse of the Big Bang.
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What is a galaxy?
What is a galaxy?
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What are the three major types of galaxies?
What are the three major types of galaxies?
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What are the two types of eclipses?
What are the two types of eclipses?
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What occurs during a lunar eclipse?
What occurs during a lunar eclipse?
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A lunar eclipse can occur at any phase of the Moon.
A lunar eclipse can occur at any phase of the Moon.
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What is the term for an eclipse where the Moon is between Earth and the Sun?
What is the term for an eclipse where the Moon is between Earth and the Sun?
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The region where no direct sunlight penetrates during a solar eclipse is called the ______.
The region where no direct sunlight penetrates during a solar eclipse is called the ______.
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The shadow where only a part of the Sun's disk is visible during a solar eclipse is known as the ______.
The shadow where only a part of the Sun's disk is visible during a solar eclipse is known as the ______.
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What is an annular eclipse?
What is an annular eclipse?
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Total and annular eclipses are classified as central eclipses.
Total and annular eclipses are classified as central eclipses.
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Study Notes
Cosmology
- The branch of astronomy that studies the origin, large-scale properties, and evolution of the observable universe.
The Universe
- In astronomy, it's the sum total of all observable things and their physical effects.
- In simpler terms, it encompasses space, matter, and energy.
- Major components include galaxies, solar systems, and planets.
The Big Bang Theory
- The most widely accepted theory regarding the universe's origin.
- Proposes the universe was created from a cosmic explosion approximately 10 to 20 billion years ago.
- This explosion propelled matter in all directions, forming galaxies.
- Observations show that galaxies are still moving apart from each other.
- Another theory, the steady-state theory, suggests continuous matter creation to fill expanding space, maintaining a constant density. However, scientific evidence supports the Big Bang.
"Big Bang" Theory
- A primeval explosion of space, time, matter, and energy.
- Estimated to have happened around 13.7 billion years ago.
- Thought to have expanded from a speck of dust-sized entity to the size of our solar system in a fraction of a second.
Edwin Hubble
- Determined that galaxies exist beyond the Milky Way.
- Observed galaxies moving away from each other.
- His observations, summarized as Hubble's Law, correlate the rate of a galaxy's recession with its distance, supporting the Big Bang Theory.
Arno Penzias & Robert Wilson
- Accidentally detected faint radiation emanating from a radio telescope in 1965.
- They determined that this radiation was leftover thermal energy from the Big Bang.
Steady State Theory
- Suggests a universe that perpetually expands but maintains a constant average density.
- Matter is continuously created to form new stars and galaxies at a rate equivalent to the rate at which old ones become unobservable as a result of increasing distance and recession velocity.
Observations & Other Endings/Theories
- Observations suggest galaxies continue to move apart.
- This theory proposes that new matter is created to fill space during expansion.
- The universe would appear similar at all times due to this.
- However, observations contradict the steady-state theory.
- Some astronomers question if the universe's expansion will continue, and the 'Big Crunch' is one potential end wherein gravity pulls galaxies together.
- Other theories also exist regarding the universe's future that involve the Big Crunch. It is considered as a plausible reverse of the Big Bang.
Galaxy
- A large assemblage of stars (and often gas and dust).
- Typically contains millions or billions of stars.
- Held together by gravitational attraction between stars.
- Formed around 200 million years after the Big Bang.
- Most large galaxies have supermassive black holes at their centers.
- Some contain bright centers called quasars.
- Three major types: Spiral, Elliptical, Irregular.
- Galaxies sometimes collide to form a larger galaxy (a process called galactic cannibalism).
Types of Stars
- The Milky Way contains different types of stars.
- Type I stars are brilliant blue and tend to be younger; fuel is used up quickly.
- Type II stars are giant red and usually older; fuel is used at a slower rate and lasts longer.
- The central and halo regions of the Milky Way contain mostly Type II (older) stars. Much of this region is obscured by dust clouds that prevent visual observation.
Types of Stars (more specifics)
- Main Sequence Stars
- Red Giants
- White Dwarfs
- Cepheid variables
- Novas
- Super novas
- Neutron stars
Constellation
- A group of stars that form a recognized pattern in the sky.
- Stars in a constellation may be far apart in space.
- Stars appear grouped due to perspective from Earth.
- Astronomers divide the sky into 88 sectors, each with a traditional constellation name.
- Patterns of constellations are dynamic; they change over millennia.
- Asterism is a part of a constellation that forms its own distinctive pattern.
Milky Way
- Our spiral galaxy roughly 30,000 parsecs across.
- Contains well over 200 billion stars.
- Its disk appears as a faint band across the night sky.
- Named after Greek mythology (milk from Hera).
- Composed of hundreds of billions of stars.
- Contains three major spiral arms: Orion, Perseus, and Sagittarius.
- The galaxy's entire system is rotating in space.
- The Sun orbits the Milky Way's nucleus approximately every 225 million years.
Solar System
- The Sun and all objects orbiting it (including planets, satellites, asteroids, and comets).
- Formed approximately 4.6 billion years ago.
- Nine planets orbit the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.
Motion of the Planets
- Planets rotate on their axis and revolve around the Sun in an elliptical orbit.
Age of the Solar System
- Evidence suggests the solar system is about 4.530 +/- 20 million years old.
- It formed in less than 25 million years.
Ringed Planets
- Four gas planets of the Solar System have rings: Jupiter, Saturn, Uranus, and Neptune.
- Saturn has the most prominent ring system.
The Sun
- The central star of our solar system.
- Essential for life on Earth.
- Provides energy for virtually all biological processes on Earth.
- Main source of energy for our solar system via a constant stream of particles.
- Emits heat, light, radiation, and ultraviolet (UV) rays; UV rays are especially harmful.
- Ozone layer of atmosphere and high energy radiation from the sun and other sources help protect harmful effects from the UV rays.
- The stream of particles from the Sun is solar wind.
- Sun's internal layers include the photosphere, chromosphere, and corona.
Earth
- The third planet from the Sun.
- Rotates on its axis every 24 hours.
- Revolves around the Sun in about 365 days and 6 hours.
- Earth's diameter is approximately 12,756 km.
- Earth is not a perfect circle but an ellipse
Structure of the Earth
- Crust
- Mantle
- Outer Core
- Inner Core
The Crust (More Details)
- The outermost solid layer of Earth.
- Composed of different types of rocks (e.g., sedimentary rocks).
- Sub-divided into ocean crust and continental crust.
The Mantle (More Details)
- Located beneath the crust.
- Primarily composed of silicate minerals.
- Temperature increases as the depth increases into the earth.
- High temps cause melting of rocks creating lava deposits used in volcanic eruptions.
The Core (More Details)
- Interior of the earth beneath the mantle.
- Outer core: thought to be a mixture of molten iron and nickel.
- Inner core: believed to be a nickel-iron alloy.
- Physical and chemical changes distinguish core from the mantle.
Earth's Atmosphere
- Composed of various gases (mainly Nitrogen, Oxygen, Argon).
Meteoroid, Meteor, Meteorite
- Meteoroid: Solid debris in space.
- Meteor: Streak of light caused by meteoroid entering Earth's atmosphere.
- Meteorite: Meteoroid that survives atmospheric entry and reaches the Earth's surface.
Comet
- Small body of ice and dust (dirty snowball).
- Orbits the Sun.
- Has a head (coma) followed by a tail of gas and dust.
- Tail always points away from the Sun.
Satellite
- Any object orbiting a more massive object (e.g., moons).
- Artificial satellites are probes launched into orbit around Earth.
Telescope
- Device for gathering electromagnetic radiation.
- Different types (visible, infrared, ultraviolet, radio) pick up various types of waves.
- Reflecting telescopes use mirrors.
- Refracting telescopes use lenses.
- Radio telescopes are not affected by weather or cloud cover.
Hubble Space Telescope
- Reflecting telescope placed in Earth's orbit.
- Collects and transmits images and measurements back to Earth electronically.
Asteroids
- Small, solid, rocky bodies.
- Orbit the Sun.
- Mostly found between Mars and Jupiter in the Asteroid Belt.
- Possibly leftover material from the formation of the solar system itself.
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Description
Explore the fascinating field of cosmology, which delves into the origins and evolution of the universe. This quiz covers key concepts such as the Big Bang theory and the universe's fundamental components. Test your knowledge on the observable cosmos and the scientific principles behind its vast expanse.
